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Introduction: Very little is known about the role of macrophages as immune mediators during natural HIV infection. Humanized mice are an extremely valuable in vivo model for studying HIV pathogenesis. However, the presence of murine mononuclear phagocytes in these models represents a significant limitation for studying their human counterpart. Therefore, we have developed a novel humanized mouse model that allows selective depletion of human myeloid cells at a time point of our choosing. Methods: We genetically engineered human hematopoietic stem and progenitor cells (HSPCs) to express an inducible caspase-9 (iCas9) suicide system under a synthetic myeloid promoter. Using these HSPCs, we generated humanized mice. iCasp9 induction in vivo resulted in selective human myeloid cell death in this inducible human myeloid depletion (iHMD) mouse model. In addition, we co-cultured monocyte-derived macrophages with ex vivo HIV-infected PBMCs to further mechanistically investigate the effect of macrophages on HIV replication using flow cytometry, cytokine analysis, and RNA sequencing of both macrophages and CD4+ T cells. Results: HIV infection induced a pro-inflammatory phenotype in HIV-infected humanized NSG mice during the early and late stages of HIV infection. Myeloid cell depletion in HIV-infected iHMD-NSG mice resulted in a rapid increase in HIV RNA replication, which was accompanied by a loss of pro-inflammatory cytokines. Co-culture of macrophages with ex vivo HIV-infected PBMCs reproduced their anti-HIV effects observed in vivo. Transcriptomic data showed macrophages upregulate antiviral cytokines and chemokines in co-culture, while inducing CD4+ T cells to upregulate HIV restriction factors and downregulate pathways involved in protein expression and cell replication. Discussion: This study describes a novel role of macrophages as effector cells, both ex vivo and in vivo , acting against HIV replication and limiting disease progression. [ABSTRACT FROM AUTHOR]

The development of a permissive small animal model for the study of human immunodeficiency virus type (HIV)-1 pathogenesis and the testing of antiviral strategies has been hampered by the inability of HIV-1 to infect primary rodent cells productively. In this study, we explored transgenic rats expressing the HIV-1 receptor complex as a susceptible host. Rats transgenic for human CD4 (hCD4) and the human chemokine receptor CCR5 (hCCR5) were generated that express the transgenes in CD4(+) T lymphocytes, macrophages, and microglia. In ex vivo cultures, CD4(+) T lymphocytes, macrophages, and microglia from hCD4/hCCR5 transgenic rats were highly susceptible to infection by HIV-1 R5 viruses leading to expression of abundant levels of early HIV-1 gene products comparable to those found in human reference cultures. Primary rat macrophages and microglia, but not lymphocytes, from double-transgenic rats could be productively infected by various recombinant and primary R5 strains of HIV-1. Moreover, after systemic challenge with HIV-1, lymphatic organs from hCD4/hCCR5 transgenic rats contained episomal 2-long terminal repeat (LTR) circles, integrated provirus, and early viral gene products, demonstrating susceptibility to HIV-1 in vivo. Transgenic rats also displayed a low-level plasma viremia early in infection. Thus, transgenic rats expressing the appropriate human receptor complex are promising candidates for a small animal model of HIV-1 infection.

Author(s): Peter Rusert [1]; Roger D Kouyos [1, 2]; Claus Kadelka [1, 2]; Hanna Ebner [1]; Merle Schanz [1]; Michael Huber [1]; Dominique L Braun [1, 2]; Nathanael Hozé [3]; [...], Broadly neutralizing antibodies (bnAbs) are a focal component of HIV-1 vaccine design, yet basic aspects of their induction remain poorly understood. Here we report on viral, host and disease factors that steer bnAb evolution using the results of a systematic survey in 4,484 HIV-1-infected individuals that identified 239 bnAb inducers. We show that three parameters that reflect the exposure to antigen--viral load, length of untreated infection and viral diversity--independently drive bnAb evolution. Notably, black participants showed significantly (P = 0.0086-0.038) higher rates of bnAb induction than white participants. Neutralization fingerprint analysis, which was used to delineate plasma specificity, identified strong virus subtype dependencies, with higher frequencies of CD4-binding-site bnAbs in infection with subtype B viruses (P = 0.02) and higher frequencies of V2-glycan-specific bnAbs in infection with non-subtype B viruses (P = 1 x 10[sup.-5]). Thus, key host, disease and viral determinants, including subtype-specific envelope features that determine bnAb specificity, remain to be unraveled and harnessed for bnAb-based vaccine design.

The HIV-1 p24 assay to dried blood spot (DBS) plasma antigen test was adapted to considerably reduce the known high background in DBS samples by introducing a peroxidase quenching step. It was found that DBS-p24 and plasma-p24 concentrations correlated well, independent of the ethnic background of the subjects or the HIV-1 subtype.

Because of species selectivity, HIV research is largely restricted to in vitro or clinical studies, both limited in their ability to rapidly assess new strategies to fight the virus. To prospectively study some aspects of HIV in vivo, immunodeficient mice, transplanted with either human peripheral blood leukocytes or human fetal tissues, have been developed. Although these are susceptible to HIV infection, xenoreactivity, and short infection spans, resource and ethical constraints, as well as biased HIV coreceptor tropic strain infection, pose substantial problems in their use. [Rag2.sup.-/-][[gamma].sub.c.sup.-/-] mice, transplanted as newborns with human CD[34.sup.+] cells, were recently shown to develop human B, T, and dendritic cells, constituting lymphoid organs in situ. Here we tested these mice as a model system for HIV-1 infection. HIV RNA levels peaked to up to 2 x [10.sup.6] copies per milliliter of plasma early after infection, and viremia was observed for up to 190 days, the longest time followed. A marked relative CD[4.sup.+] T cell depletion in peripheral blood occurred in CXCR4-tropic strain-infected mice, whereas this was less pronounced in CCR5-tropic strain-infected animals. Thymus infection was almost exclusively observed in CXCR4-tropic strain-infected mice, whereas spleen and lymph node HIV infection occurred irrespective of coreceptor selectivity, consistent with respective coreceptor expression on human CD[4.sup.+] T cells. Thus, this straightforward to generate and cost-effective in vivo model closely resembles HIV infection in man and therefore should be valuable to study virus-induced pathology and to rapidly evaluate new approaches aiming to prevent or treat HIV infection.

Research has been conducted on the human infections by Marburg and Ebola viruses. The identification of the cellular entry factors used by the viruses has been carried out via the noninfectible cells challenged with the selectable pseudotype virus packaged by the Marburg glycoproteins and the results are presented.

Background: Fetal surgery for spina bifida aperta may lead to significantly better outcomes than postnatal repair, particularly regarding shunt-dependent hydrocephalus, independent ambulation, and voiding functions. The "Management of Myelomeningocele Study" (MOMS) represents the current benchmark, also in terms of eligibility criteria.Case Report: A positive maternal hepatitis B virus (HBV) status is a MOMS exclusion criterion. Here, we report on the first successful active and passive in utero HBV vaccination of a spina bifida fetus carried by a HBV-positive mother undergoing maternal-fetal surgery. The now 2-year-old infant is healthy, HBV negative, and drew maximal benefit from prenatal surgery.Discussion and Conclusion: Taken together, this patient benefitted maximally from fetal surgery for spina bifida, despite meeting an exclusion criterion. Thus, generally speaking, eligibility criteria for fetal surgery can be challenged under certain circumstances for the benefit of the patient. [ABSTRACT FROM AUTHOR]