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Tuberculosis (TB) is an increasing global emergency in human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) patients, in which host immunity is dysregulated and compromised. However, the pathogenesis and efficacy of therapeutic strategies in HIV-associated TB in developing infants are essentially lacking. Bacillus Calmette-Guerin vaccine, an attenuated live strain of Mycobacterium bovis, is not adequately effective, which confers partial protection against Mycobacterium tuberculosis (Mtb) in infants when administered at birth. However, pediatric HIV infection is most devastating in the disease progression of TB. It remains challenging whether early antiretroviral therapy (ART) could maintain immune development and function, and restore Mtb-specific immune function in HIV-associated TB in children. A better understanding of the immunopathogenesis in HIV-associated pediatric Mtb infection is essential to provide more effective interventions, reducing the risk of morbidity and mortality in HIV-associated Mtb infection in infants. IMPACT: Children living with HIV are more likely prone to opportunistic infection, predisposing high risk of TB diseases. HIV and Mtb coinfection in infants may synergistically accelerate disease progression. Early ART may probably induce immune reconstitution inflammatory syndrome and TB pathology in HIV/Mtb coinfected infants.

The HIV reservoir size in target CD4+ T cells during primary infection remains unknown. Here, we sorted peripheral and intestinal CD4+ T cells and quantified the levels of cell-associated SIV RNA and DNA in rhesus macaques within days of SIVmac251 inoculation. As a major target cell of HIV/SIV, CD4+ T cells in both tissues contained a large amount of SIV RNA and DNA at day 8–13 post-SIV infection, in which productive SIV RNA highly correlated with the levels of cell-associated SIV DNA. Memory CD4+ T cells had much higher viral RNA and DNA than naïve subsets, yet memory CD4+ T cells co-expressing CCR5 had no significant reservoir size compared with those that were CCR5-negative in blood and intestine. Collectively, memory CD4+ T cells appear to be the major targets for primary infection, and viral reservoirs are equally distributed in systemic and lymphoid compartments in acutely SIV-infected macaques.

C-C chemokine receptor 5 (CCR5) plays an essential role in HIV pathogenesis as the major coreceptor on CD4+ T cells used by HIV, yet the function of CCR5 on CD8 T cells is not well understood. Furthermore, the immunologic effects of the CCR5 inhibitor maraviroc (MVC), despite approval for clinical use, have not yet been well evaluated for their potential effects on cytotoxic T-cell responses. In this study, we characterized the development and function of CCR5+CD8+ T cells in rhesus macaques with or without Simian immunodeficiency virus (SIV) infection. We also investigated the effects of the CCR5 antagonist MVC on functional CCR5+CD8+ T-cell responses in vitro. The data show that CCR5+CD8+ T cells have an effector memory phenotype and increase with age in systemic and mucosal lymphoid tissues as a heterogeneous population of polyfunctional CD8 T cells. In addition, CCR5 is highly expressed on SIV gag-specific (CM9+) CD8+ T cells in SIV-infected macaques, yet CCR5+CD8+ T cells are significantly reduced in mucosal lymphoid tissues with disease progression. Furthermore, in vitro MVC treatment reduced activation and cytokine secretion of CD8+ T cells via a CCR5-independent pathway. These findings suggest that surface CCR5 protein plays an important role in differentiation and activation of CD8+ T cells. Although MVC may be helpful in reducing chronic inflammation and activation, it may also inhibit virus-specific CD8+ T-cell responses. Thus optimal use of CCR5 antagonists either alone or in combination with other drugs should be defined by further investigation.-Wang, X., Russell-Lodrigue, K. E., Ratterree, M. S., Veazey, R. S., Xu, H. Chemokine receptor CCR5 correlates with functional CD8+ T cells in SIV-infected macaques and the potential effects of maraviroc on T-cell activation.

Neonatal HIV infection causes rapid disease progression to end-stage of AIDS if untreated. To date, there are no reported cases of a genuine functional cure in Pediatric AIDS ClinicalTrial Group lacking integrase inhibitor regimen, even when initiated early. In this study, three infant rhesus macaques born on the same day were intravenously infected with SIV on the day of birth and received ART containing tenofovir, FTC, and dolutegravir (DTG) initiated 3 days post infection and continued daily for 9 months. The results showed early ART combination effectively suppressed viral replication to undetectable viremia throughout the treatment course. Remarkably, two of three infants showed complete virologic remission and intestinal CD4+ T cell preservation throughout the period of studyafter analytical treatment interruption (ATI), as well as undetectable cell-associated proviral DNA in PBMCs, axillary lymph nodes (LNs), and rectal biopsies. However, viral rebound was observed in one of the three infants at two months post ATI. Notably, very low levels of integrated proviral SIV DNA were detected in the lymph node of this animal under cART. Sustained virologic remission was achieved in the other two infants despite absence of protective MHC alleles or neutralizing antibody responses. These findings suggest that early integrase inhibitor-based ART, initiated before irreversible proviral reservoir seeding, can completely suppress viral replication and effectively block new viral genome integration, providing a proof of concept that HIV functional cure and possibly a cure is possible, at least in a proportion of infants postnatally infected with HIV.

SHIVs have been extensively used in a nonhuman primate (NHP) model for HIV research. In this study, we investigated viral reservoirs in tissues and immune responses in an NHP model inoculated with newly generated transmitted/founder HIV-1 clade C-based SHIV.C.CH848., Chimeric simian/human immunodeficiency viruses (SHIVs) are widely used in nonhuman primate models to recapitulate human immunodeficiency virus (HIV) infection in humans, yet most SHIVs fail to establish persistent viral infection. We investigated immunological and virological events in rhesus macaques infected with the newly developed SHIV.C.CH848 (SHIVC) and treated with combined antiretroviral therapy (cART). Similar to HIV/simian immunodeficiency virus (SIV) infection, SHIV.C.CH848 infection established viral reservoirs in CD4+ T cells and myeloid cells, accompanied by productive infection and depletion of CD4+ T cells in systemic and lymphoid tissues throughout SHIV infection. Despite 6 months of cART-suppressed viral replication, integrated proviral DNA levels remained stable, especially in CD4+ T cells, and the viral rebound was also observed after ART interruption. Autologous neutralizing antibodies to the parental HIV-1 strain CH848 were detected, with limited viral evolution at 5 months postinfection. In comparison, heterogenous neutralizing antibodies in SHIV.C.CH848-infected macaques were not detected except for 1 (1 of 10) animal at 2 years postinfection. These findings suggest that SHIV.C.CH848, a novel class of transmitted/founder SHIVs, can establish sustained viremia and viral reservoirs in rhesus macaques with clinical immunodeficiency consequences, providing a valuable SHIV model for HIV research. IMPORTANCE SHIVs have been extensively used in a nonhuman primate (NHP) model for HIV research. In this study, we investigated viral reservoirs in tissues and immune responses in an NHP model inoculated with newly generated transmitted/founder HIV-1 clade C-based SHIV.C.CH848. The data show that transmitted founder (T/F) SHIVC infection of macaques more closely recapitulates the virological and clinical features of HIV infection, including persistent viremia and viral rebound once antiretroviral therapy is discontinued. These results suggest this CCR5-tropic, SHIVC strain is valuable for testing responses to HIV vaccines and therapeutics.

Viral reservoirs are involved in persistent HIV infection, and a small number of mosaic latent cellular reservoirs promote viral rebound upon analytical treatment interruption, which is the major obstacle to a cure. However, early indicators that can predict resurgence of viremia after treatment interruption may aid treatment decisions in people living with HIV., The human immunodeficiency virus (HIV) reservoir is responsible for persistent viral infection, and a small number of mosaic latent cellular reservoirs promote viral rebound upon antiretroviral therapy interruption, which is the major obstacle to a cure. However, markers that determine effective therapy and viral rebound posttreatment interruption remain unclear. In this study, we comprehensively and longitudinally tracked dynamic decay of cell-associated viral RNA/DNA in systemic and lymphoid tissues in simian immunodeficiency virus (SIV)-infected rhesus macaques on prolonged combined antiretroviral therapy (cART) and evaluated predictors of viral rebound after treatment cessation. The results showed that suppressive ART substantially reduced plasma SIV RNA, cell-associated unspliced, and multiply spliced SIV RNA to undetectable levels, yet viral DNA remained detectable in systemic tissues and lymphoid compartments throughout cART. Intriguingly, a rapid increase of integrated proviral DNA in peripheral mononuclear cells was detected once treatment was withdrawn, accompanied by the emergence of detectable plasma viral load. Notably, the increase of peripheral proviral DNA after treatment interruption correlated with the emergence and degree of viral rebound. These findings suggest that measuring total viral DNA in SIV infection may be a relatively simple surrogate marker of reservoir size and may predict viral rebound after treatment interruption and inform treatment strategies. IMPORTANCE Viral reservoirs are involved in persistent HIV infection, and a small number of mosaic latent cellular reservoirs promote viral rebound upon analytical treatment interruption, which is the major obstacle to a cure. However, early indicators that can predict resurgence of viremia after treatment interruption may aid treatment decisions in people living with HIV. Utilizing the rhesus macaque model, we demonstrated that increased proviral DNA in peripheral cells after treatment interruption, rather than levels of proviral DNA, was a useful marker to predict the emergence and degree of viral rebound after treatment interruption, providing a rapid approach for monitoring HIV rebound and informing decisions.

Antiretroviral therapy (ART) has dramatically suppressed human immunodeficiency virus (HIV) replication and become undetectable viremia. However, a small number of residual replication-competent HIV proviruses can still persist in a latent state even with lifelong ART, fueling viral rebound in HIV-infected patient subjects after treatment interruption. Therefore, the proviral reservoirs distributed in tissues in the body represent a major obstacle to a cure for HIV infection. Given unavailable HIV vaccine and a failure to eradicate HIV proviral reservoirs by current treatment, it is crucial to develop new therapeutic strategies to eliminate proviral reservoirs for ART-free HIV remission (functional cure), including a sterilizing cure (eradication of HIV reservoirs). This review highlights recent advances in the establishment and persistence of HIV proviral reservoirs, their detection, and potential eradication strategies.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is highly contagious presenting a significant public health issue. Current therapies used to treat coronavirus disease 2019 (COVID-19) include monoclonal antibody cocktail, convalescent plasma, antivirals, immunomodulators, and anticoagulants, though the current therapeutic options remain limited and expensive. The vaccines from Pfizer and Moderna have recently been authorized for emergency use, which are invaluable for the prevention of SARS-CoV-2 infection. However, their long-term side effects are not yet to be documented, and populations with immunocompromised conditions (e.g., organ-transplantation and immunodeficient patients) may not be able to mount an effective immune response. In addition, there are concerns that wide-scale immunity to SARS-CoV-2 may introduce immune pressure that could select for escape mutants to the existing vaccines and monoclonal antibody therapies. Emerging evidence has shown that chimeric antigen receptor (CAR)- natural killer (NK) immunotherapy has potent antitumor response in hematologic cancers with minimal adverse effects in recent studies, however, the potentials of CAR-NK cells in preventing and treating severe cases of COVID-19 has not yet been fully exploited. Here, we improve upon a novel approach for the generation of CAR-NK cells for targeting SARS-CoV-2 and its D614G mutant. CAR-NK cells were generated using the scFv domain of S309 (henceforward, S309-CAR-NK), a SARS-CoV and SARS-CoV-2 neutralizing antibody that targets the highly conserved region of SARS-CoV-2 spike (S) glycoprotein, therefore would be more likely to recognize different variants of SARS-CoV-2 isolates. S309-CAR-NK cells can specifically bind to pseudotyped SARS-CoV-2 virus and its D614G mutant. Furthermore, S309-CAR-NK cells can specifically kill target cells expressing SARS-CoV-2 S protein in vitro and show superior killing activity and cytokine production, compared to that of the recently published CR3022-CAR-NK cells. Thus, these results pave the way for generating ‘off-the-shelf’ S309-CAR-NK cells for treatment in high-risk individuals as well as provide an alternative strategy for patients unresponsive to current vaccines.

Cellular viral reservoirs are rapidly established in tissues upon HIV‐1/SIV infection, which persist throughout viral infection, even under long‐term antiretroviral therapy (ART). Specific integrins are involved in the homing of cells to gut‐associated lymphoid tissues (GALT) and inflamed tissues, which may promote the seeding and dissemination of HIV‐1/SIV to these tissue sites. In this study, we investigated the efficacy of prophylactic integrin blockade (α4β7 antibody or α4β7/α4β1 dual antagonist TR‐14035) on viral infection, as well as dissemination and seeding of viral reservoirs in systemic and lymphoid compartments post‐SIV inoculation. The results showed that blockade of α4β7/α4β1 did not decrease viral infection, replication, or reduce viral reservoir size in tissues of rhesus macaques after SIV infection, as indicated by equivalent levels of plasma viremia and cell‐associated SIV RNA/DNA to controls. Surprisingly, TR‐14035 administration in acute SIV infection resulted in consistently higher viremia and more rapid disease progression. These findings suggest that integrin blockade alone fails to effectively control viral infection, replication, dissemination, and reservoir establishment in HIV‐1/SIV infection. The use of integrin blockade for prevention or/and therapeutic strategies requires further investigation.

A robust simian-human immunodeficiency virus (SHIV)-macaque model of latency is critical to investigate eradicative and suppressive strategies that target HIV-1 Env. To this end, we previously reported a novel strategy for constructing SHIVs that bear primary or transmitted/founder (TF) Envs with modifications at Env residue 375 that enable efficient replication in Indian rhesus macaques (RM). Such TF SHIVs, however, have not been examined for their suitability for HIV-1 latency and cure research. Here, we evaluate two promising TF SHIVs, SHIV.D.191859 and SHIV.C.CH848, which encode TF subtype D and C HIV-1 Envs, respectively, for their viral kinetics and persistence during suppressive combination antiretroviral therapy (cART) and treatment interruption in RM. Our results suggest that the viral kinetics of these SHIVs in RM during acute, early, and chronic infection, and upon cART initiation, maintenance and discontinuation, mirror those of HIV-1 infection. We demonstrate consistent early peak and set point viremia, rapid declines in viremia to undetectable plasma titers following cART initiation, infection of long-lived cellular subsets and establishment of viral latency, and viral rebound with return to pretreatment set point viremia following treatment interruption. The viral dynamics and reservoir biology of SHIV.D.191859, and to a lesser extent SHIV.C.CH848, during chronic infection, cART administration, and upon treatment interruption suggest that these TF SHIVs are promising reagents for a SHIV model of HIV-1 latency and cure. IMPORTANCE Simian-human immunodeficiency viruses (SHIVs) have been successfully used for over 2 decades to study virus-host interactions, transmission, and pathogenesis in rhesus macaques. The majority of Env trimers of most previously studied SHIVs, however, do not recapitulate key properties of transmitted/founder (TF) or primary HIV-1 isolates, such as CCR5 tropism, tier 2 neutralization resistance, and native trimer conformation. Here, we test two recently generated TF SHIVs, SHIV.D.191859 and SHIV.C.CH848, which were designed to address these issues as components of a nonhuman primate model of HIV-1 latency. We conclude that the TF SHIV-macaque model reflects several hallmarks of HIV and SIV infection and latency. Results suggest that this model has broad applications for evaluating eradicative and suppressive strategies against the HIV reservoir, including Env-specific interventions, therapeutic vaccines, and engineered T cells.

Germinal center (GC) CD4+ follicular Th (Tfh) cells are critical for cognate B cell help in humoral immune responses to pathogenic infections. Although Tfh cells are expanded or depleted in HIV/SIV-infected adults, the effects of pediatric HIV/SIV infection on Tfh cells remain unclear. In this study, we examined changes in lymphoid follicle formation in lymph nodes focusing on GC Tfh cells, B cell development, and differentiation in SIV-infected neonatal rhesus macaques (Macaca mulatta) compared with age-matched cohorts. Our data showed that follicles and GCs of normal infants rapidly formed in the first few weeks of age, in parallel with increasing GC Tfh cells in various lymphoid tissues. In contrast, GC development and GC Tfh cells were markedly impaired in SIV-infected infants. There was a very low frequency of GC Tfh cells throughout SIV infection in neonates and subsequent infants, accompanied by high viremia, reduction of B cell proliferation/resting memory B cells, and displayed proinflammatory unresponsiveness. These findings indicate neonatal HIV/SIV infection compromises the development of GC Tfh cells, likely contributing to ineffective Ab responses, high viremia, and eventually rapid disease progression to AIDS.

The scientific foundation of artificial weather modification is meso- and small-scale dynamics and cloud–precipitation microphysics. Artificial weather modification requires the realistic coupling of weather patterns, dynamical processes, and microphysical processes. Now that numerical models with weather dynamical characteristics have been widely applied to artificial weather modification, several key points that should not be neglected when developing numerical models for artificial weather modification are proposed in this paper, including the dynamical equations, model resolution, cloud–precipitation microphysical processes, numerical computation method, and initial and boundary conditions. Based on several examples, approaches are offered to deal with the problems that exist in these areas.

Conventional HIV T cell vaccine strategies have not been successful in containing acute peak viremia, nor in providing long-term control. We immunized rhesus macaques intramuscularly and rectally using a heterologous adenovirus vectored SIV vaccine regimen encoding normally weakly immunogenic tat, vif, rev and vpr antigens fused to the MHC class II associated invariant chain. Immunizations induced broad T cell responses in all vaccinees. Following up to 10 repeated low-dose intrarectal challenges, vaccinees suppressed early viral replication (P=0.01) and prevented the peak viremia in 5/6 animals. Despite consistently undetectable viremia in 2 out of 6 vaccinees, all animals showed evidence of infection induced immune responses indicating that infection had taken place. Vaccinees, with and without detectable viremia better preserved their rectal CD4+ T cell population and had reduced immune hyperactivation as measured by naive T cell depletion, Ki-67 and PD-1 expression on T cells. These results indicate that vaccination towards SIV accessory antigens vaccine can provide a level of acute control of SIV replication with a suggestion of beneficial immunological consequences in infected animals of unknown long-term significance. In conclusion, our studies demonstrate that a vaccine encoding subdominant antigens not normally associated with virus control can exert a significant impact on acute peak viremia.

Malignant syphilis is a rare skin manifestation of secondary syphilis, which has been reported primarily in the HIV-infected population. This study aimed to investigate the relationship between HIV infection, malignant syphilis, and neurosyphilis through a systematic chart review of 26 malignant syphilis patients seen at our hospital. We also performed a literature review of 83 reported malignant syphilis cases since 1987, when the first case of malignant syphilis co-infected with HIV was reported. We found there was no direct association between HIV infection and malignant syphilis or neurosyphilis. In contrast, we found that much higher proportion (30%) of malignant syphilis patients develop concurrent neurosyphilis compared to those with the common type of secondary syphilis (13.1%). Physicians should be aware of the fact that neurosyphilis is more common among patients with malignant syphilis and the importance of investigating for neurosyphilis in such patients.

C-C chemokine receptor 5 (CCR5) plays an essential role in HIV pathogenesis as the major coreceptor on CD4(+) T cells used by HIV, yet the function of CCR5 on CD8 T cells is not well understood. Furthermore, the immunologic effects of the CCR5 inhibitor maraviroc (MVC), despite approval for clinical use, have not yet been well evaluated for their potential effects on cytotoxic T-cell responses. In this study, we characterized the development and function of CCR5(+)CD8(+) T cells in rhesus macaques with or without Simian immunodeficiency virus (SIV) infection. We also investigated the effects of the CCR5 antagonist MVC on functional CCR5(+)CD8(+) T-cell responses in vitro. The data show that CCR5(+)CD8(+) T cells have an effector memory phenotype and increase with age in systemic and mucosal lymphoid tissues as a heterogeneous population of polyfunctional CD8 T cells. In addition, CCR5 is highly expressed on SIV gag-specific (CM9(+)) CD8(+) T cells in SIV-infected macaques, yet CCR5(+)CD8(+) T cells are significantly reduced in mucosal lymphoid tissues with disease progression. Furthermore, in vitro MVC treatment reduced activation and cytokine secretion of CD8(+) T cells via a CCR5-independent pathway. These findings suggest that surface CCR5 protein plays an important role in differentiation and activation of CD8(+) T cells. Although MVC may be helpful in reducing chronic inflammation and activation, it may also inhibit virus-specific CD8(+) T-cell responses. Thus optimal use of CCR5 antagonists either alone or in combination with other drugs should be defined by further investigation.—Wang, X., Russell-Lodrigue, K. E., Ratterree, M. S., Veazey, R. S., Xu, H. Chemokine receptor CCR5 correlates with functional CD8(+) T cells in SIV-infected macaques and the potential effects of maraviroc on T-cell activation.

The difficulty in detecting rare infected cells immediately after mucosal HIV transmission has hindered our understanding of the initial cells targeted by the virus. Working with the macaque-simian immunodeficiency virus (SIV) vaginal challenge model, we developed methodology to identify discrete foci of SIV (mac239) infection 48 hours after vaginal inoculation. We find infectious foci throughout the reproductive tract, from labia to ovary. Phenotyping infected cells reveals that SIV has a significant bias for infection of CCR6+ CD4+ T cells. SIV infected cells expressed the transcriptional regulator RORγt confirming that the initial target cells are specifically of the Th17 lineage. Furthermore, we detect host responses to infection, as evidenced by apoptosis, cell lysis, and phagocytosis of infected cells. Thus, our analysis identifies Th17 lineage CCR6+ CD4+ T cells as primary targets of SIV during vaginal transmission. This opens new opportunities for interventions to protect these cells and prevent HIV transmission.

CD4 + follicular T helper (Tfh) cells play a prominent role in humoral immune responses, but the mechanisms of their accumulation and infection in AIDS remain unclear. Here we found that germinal center (GC) Tfh cells, defined here as CXCR5 + PD-1 HIGH CD4 + T cells, do not express the HIV coreceptor CCR5 yet serve as a latent reservoir in GCs. With disease progression, an expansion of GC Tfh cells is accompanied by increases in dysfunctional CD8 + T cells. In contrast, Tfh precursor (CXCR5 − CD4 + T) cells in lymph nodes do express CCR5 and differentiate into GC Tfh cells following interleukin-6 (IL-6) and IL-21 stimulation, and viral DNA is detectable in fully differentiated GC Tfh cells ex vivo . This suggests that SIV-infected GC Tfh cells may be derived from Tfh precursor cell subsets that become infected in marginal zones and then migrate into GCs as fully mature GC Tfh cells that serve as persistent virus reservoirs. These findings suggest that viral persistence in lymph nodes drives compensatory differentiation, aberrant accumulation, and latent infection of GC Tfh cells, resulting in marked impairment of humoral immune responses. IMPORTANCE Generation of antibodies that can effectively eliminate viruses requires interactions of B cells with highly specialized T cells in GCs of lymphoid tissues called follicular T helper cells. Here we show that in simian immunodeficiency virus infection, these cells are initially infected in a precursor stage that leads to alterations in their homing, accumulation, and function that may be responsible for the inability of human immunodeficiency virus-infected patients to generate effective antibody responses.

Material & Method By quantitative real-time/digital PCR, we here longitudinally examined dynamic decay of viral parameters (cell-associated unspliced and multiply spliced viral RNA, episomal 2-LTR circular viral DNA and integrated proviral DNA) in systemic and lymphoid tissues in SIV-infected rhesus macaques on long-term combined antiretroviral therapy (cART, up to 20 months), and evaluated reservoir size and timing of viral rebound after treatment interruption. SIV RNA or DNA copy numbers were normalized and expressed as per 106 cell equivalents. Frequencies and absolute numbers of peripheral CD4+ T cells were analyzed before and after suppressive antiretroviral therapy. Results Our results showed that suppressive ART significantly reduced levels of cell-associated unspliced and multiply spliced SIV RNA/2-LTR DNA to undetectable, yet levels of integrated proviral DNA alone were stably maintained in systemic and lymphoid compartments throughout cART, which correlated with levels of viral replication prior to initiating cART. Following ATI, rapid clonal expansion of cells with integrated provirus were detected, as indicated by undetectable spliced tat/rev RNA and 2-LTR but increased levels of total proviral DNA, which may have contributed to subsequent viral rebound. Cell-associated SIV RNA and DNA levels completely recovered to pre-treatment levels in blood, spleen, lymph node, tonsil and gut-associated lymphoid tissues by 3 months after ATI. Conclusions These findings suggest that discriminating integrated HIV proviral DNA from non-integrated or defective proviruses in tissues are useful biomarkers for monitoring HIV persistence and latency for treatment and cure strategies.

Background The chimeric simian/human immunodeficiency viruses (SHIVs), carrying HIV envelope glycoproteins from transmitted founder (T/F) viruses, are valuable as a challenge viruses in nonhuman primate models for validating HIV-1 vaccines, assessing viral reservoirs and latency, and developing functional “cure” strategies in HIV infection. This study comprehensively investigated immunological changes, viral replication and reservoir size in deep tissues of SHIV-CH848-infected rhesus macaques on antiretroviral therapy (cART). Material & Method A total of 10 rhesus macaques (Macaca mulatta, RMs) were intravenously (i.v.)inoculated with SHIV-CH848, containing vpu-env(gp140) sequence from T/F HIV-1 subtype C strain CH848. At 3 months post SHIV infection, 5 animals received cART for 6 months, and remaining 5 animals as untreated controls. Blood, lymph node and rectal biopsies were collected to examine plasma viral load, cell-associated viral RNA/DNA and host immune responses. Results SHIV-CH848 inoculation resulted in rapid viral replication, reaching peak viremia at 14dpi. SHIV-CH848 primary infection significantly depleted peripheral and mucosal CD4+ T cells. Also, broadly neutralizing antibodies were also not elicited up to 15 months post infection. Despite gradual recovery of CD4+ T cells after cART, the levels of integrated viral DNA in tissues remained stable throughout 6-months of cART, and rapid viral rebound was observed after ART interruption. Conclusions These findings suggest that the new SHIV strain, SHIV-CH848, is able to maintain persistent viral replication in macaques, and establish long-term viral reservoirs/latency in tissues, serving as a valuable model for HIV research.

Supplemental Material for Neurosyphilis is more common in malignant syphilis: A case series and review of the literature by Lin Zhu, Mei Shi, Rui-Rui Peng, Xin Gu, Zhifang Guan, Huanbin Xu and Pingyu Zhou in International Journal of STD & AIDS

Exosomes are small extracellular vesicles (EVs), released by a wide variety of cell types, carry donor origin-proteins, cytokines, and nucleic acids, transport these cargos to adjacent or distant specific recipient cells, and thereby regulate gene expression and activation of target cells. In this study, we isolated and identified exosomes in rhesus macaques, and investigated their effects on cell tropism and activation, especially their potential to reactivate HIV latency. The results indicated that plasma-derived exosomes preferentially fuse to TCR-activated T cells and autologous parent cells. Importantly, the uptake of exosomes, derived from IL-2 stimulated CD4+ T cells, effectively promoted reactivation of resting CD4+ T-cell, as indicated by an increased viral transcription rate in these cells. These findings provide premise for the potential application of exosome in the reactivation of HIV latency, in combination its use as functional delivery vehicles with antiretroviral therapy (ART).

The production of high-affinity and broadly neutralizing antibodies (bnAbs) plays a key role in the defense against pathogens. These antibody responses require effective germinal center (GC) reaction within anatomical niches of GCs, where follicular T (Tfh) cells provide cognate help to B cells for T cell-dependent antibody responses. Emerging evidences indicate that GC reaction in normal state and perhaps establishment of latent Tfh cell reservoir in HIV/SIV infection are tightly regulated by epigenetic histone modifications, which are responsible for activating or silencing chromatin. A better understanding of the mechanisms behind GC responses, at cellular and molecular levels, thus provides necessary knowledge for vaccination and immunotherapy. In this review, we discussed the epigenetic regulation of germinal center responses, especially for GC B and Tfh cell under normal state or HIV/SIV infection.

Impairment of the intestinal mucosal immune system is an early feature of HIV-infected children. Most infected children exhibit clinical gastrointestinal symptoms at some stage of infection, and persistent diarrhea is a marker for rapid disease progression. It is known that Tregs are especially important in mediating intestinal immune homeostasis and that loss of this subset may result in intestinal inflammation and associated clinical signs. Large numbers of FoxP3+ T cells were found in all tissues in newborn macaques, which coexpressed high levels of CD25 and CD4, indicating that they were Tregs. Moreover, neonates had much greater percentages of Tregs in intestinal tissues compared with peripheral lymphoid tissues. After SIV infection, a significant loss of Tregs was detected in the intestine compared with age-matched normal infants. Finally, SIV-infected FoxP3+ T cells were detected in tissues in neonates as early as 7 SIV dpi. These results demonstrate that Tregs constitute a significant fraction of CD4+ T cells in neonatal intestinal tissues and that an early, profound loss of Tregs occurs in acute SIV infection, which may contribute to the intestinal disorders associated with neonatal HIV infection.

Cellular viral reservoirs are rapidly established upon HIV/SIV infection, which persist throughout viral infection, even under long-term antiretroviral therapy (ART). Recent studies report α4β7 blockade in vivo could preserve mucosal CD4+ T cells, and control persistent viral infection in SIV-infected macaques. In this study, we investigated the effects of early administration with α4β7 antagonist (antibody against α4β7 or small-molecule dual inhibitor TR-14035) for the prevention of infection, and for reducing cellular reservoirs in systemic and lymphoid tissues post SIV infection. Rhesus macaques (Macaca mulatta, RMs) were intravenously (i.v.) inoculated with 100 TCID50 SIVmac251, then administrated a single i.v. dose of anti-α4β7mAb one week prior to SIV inoculation and another 3 weeks post SIV inoculation, or orally treated with TR-14035 for two weeks beginning on the day of SIV inoculation. Our results indicated that early α4β7 blockade did not result in viral containment or reduction of the reservoir size post SIV infection. Plasma viral loads and cell-associated SIV DNA/RNA levels in blood and lymphoid tissues in treated animals were similar to untreated cohorts. Interestingly, TR-14035, a dual inhibitor for α4β7 and α4β1, resulted in persistently higher viremia throughout infection, and more rapid disease progression when administrated in the acute stage of SIV infection. Conclusions These findings suggest that α4β7 blockade alone may not effectively control viral infection, replication, and dissemination and reservoir establishment in HIV/SIV infection. Its usage for potential preventive or/and therapeutic strategies in combined with ART requires further investigation.

Biphasic and progressive downregulation of CD8 occurs on virus-specific T cells in SIV infection, which correlates with decreased cell function. Functional impairment of virus-specific T cells is a hallmark of HIV/SIV infection, but the underlying mechanisms of this dysfunction are not well understood. To address this, we simultaneously analyzed the expression and intensity of CD8 and inhibitory PD-1 on CTL in blood and lymphoid tissues in SIV-infected rhesus macaques. The intensity (mean channel fluorescence) of CD8 expression was transiently down-regulated in early SIV infection (10–14 dpi), despite an increase in CD8+ T cell proliferation. In chronic infection, CD8 expression was maintained at low levels on CD8+ T cells in all tissues. Interestingly, Gag-specific CTLs were clearly divided into CD8high- and CD8low-expressing populations in SIV-infected macaques, and CD8low Gag-specific cells increased with disease progression, especially in lymphoid tissues when compared with peripheral blood or in Gag-vaccinated controls. Moreover, the CD8low CTL population secreted lower levels of cytokines upon SIV antigen stimulation and exhibited lower proliferative capacity during infection compared with the CD8high CTL population. Meanwhile, intensity of PD-1 expression on Gag-specific CTL in chronic infection was significantly higher than in acute SIV infection, although the frequencies of PD-1+ Gag-specific cells were similar in acute and chronic stages. In summary, down-regulation of CD8 expression and higher expression of PD-1 on SIV-specific CTLs could coordinately attenuate SIV-specific CTL responses and their ability to recognize virus-infected target cells, especially in lymphoid tissues, resulting in failure to contain viremia, and continued persistence and replication of HIV in lymphoid tissue reservoirs.

The persistence of latently HIV-infected cellular reservoirs represents the major obstacle to virus eradication in patients under antiretroviral therapy (ART). Cure strategies to eliminate these reservoirs are thus needed to reactivate proviral gene expression in latently infected cells. In this study, we tested optimal concentrations of PKC agonist candidates (PEP005/Ingenol-3-angelate, prostratin, bryostatin-1, and JQ1) to reactivate HIV latency in vitro, and examined their effects on cell survival, activation and epigenetic histone methylation after treatment alone or in combination in cell line and isolated CD4 T cells from SIV-infected macaques. The results showed that PKC agonists increased cell activation with different degrees of latency reactivation, concomitant with reduced levels of histone methylation. With increasing concentrations, prostratin and byrostain-1 treatment rapidly reduced cell survival and cell activation. The PKC agonist combinations, or in combination with JQ1, led to modest levels of synergistic reactivation of HIV. Remarkably, PEP005 treatment alone caused marked reactivation of HIV latency, similar to PMA stimulation. These findings suggested that PEP005 alone, as indicated its lower cytotoxicity and lower effective dose inducing maximal reactivation, might be a candidate for effectively reactivating HIV latency as part of a therapeutic strategy for HIV infection.

Follicular CD4+ T helper (TFH) cells interact with B cells in follicular germinal centers and play a prominent role in promoting effective humoral immune responses to pathogens, providing help for B cell development and antibody affinity maturation. Recent studies indicate TFH cells are expanded in HIV/SIV chronic infection, or depleted in terminal stages of disease, yet relatively maintained in elite controllers when compared with uninfected controls. A better understanding of the mechanisms behind these immunologic abnormalities may lead to more effective vaccination and therapeutic strategies. Here, we review recent findings of TFH cells in HIV/SIV infection and discuss the correlation of changes and function of TFH cells with host immunity. Dysregulation or depletion of CD4+ TFH cells likely plays a major role in the inability of HIV-infected patients to mount effective immune responses.

Bone marrow is thought to be a primary hematopoietic organ. However, accumulated evidences demonstrate that active function and trafficking of immune cells, including regulatory T cells, conventional T cells, B cells, dendritic cells, natural killer T (NKT) cells, neutrophils, myeloid-derived suppressor cells and mesenchymal stem cells, are observed in the bone marrow. Furthermore, bone marrow is a predetermined metastatic location for multiple human tumors. In this review, we discuss the immune network in the bone marrow. We suggest that bone marrow is an immune regulatory organ capable of fine tuning immunity and may be a potential therapeutic target for immunotherapy and immune vaccination.