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Background Longer-term humoral responses to 2-dose coronavirus disease 2019 (COVID-19) vaccines remain incompletely characterized in people living with human immunodeficiency virus (HIV) (PLWH), as do initial responses to a third dose. Methods We measured antibodies against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein receptor-binding domain, angiotensin-converting enzyme 2 (ACE2) displacement, and viral neutralization against wild-type and Omicron strains up to 6 months after 2-dose vaccination, and 1 month after the third dose, in 99 PLWH receiving suppressive antiretroviral therapy and 152 controls. Results Although humoral responses naturally decline after 2-dose vaccination, we found no evidence of lower antibody concentrations or faster rates of antibody decline in PLWH compared with controls after accounting for sociodemographic, health, and vaccine-related factors. We also found no evidence of poorer viral neutralization in PLWH after 2 doses, nor evidence that a low nadir CD4+ T-cell count compromised responses. Post–third-dose humoral responses substantially exceeded post–second-dose levels, though Omicron-specific responses were consistently weaker than responses against wild-type virus. Nevertheless, post–third-dose responses in PLWH were comparable to or higher than controls. An mRNA-1273 third dose was the strongest consistent correlate of higher post–third-dose responses. Conclusion PLWH receiving suppressive antiretroviral therapy mount strong antibody responses after 2- and 3-dose COVID-19 vaccination. Results underscore the immune benefits of third doses in light of Omicron.

BackgroundLonger-term immune response data after 3 doses of coronavirus disease 2019 (COVID-19) mRNA vaccine remain limited, particularly among older adults and after Omicron breakthrough infection.MethodsWe quantified wild-type- and Omicron-specific serum immunoglobulin (Ig)G levels, angiotensin-converting enzyme 2 displacement activities, and live virus neutralization up to 6 months after third dose in 116 adults aged 24–98 years who remained COVID-19 naive or experienced their first severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection during this time.ResultsAmong the 78 participants who remained COVID-19 naive throughout follow up, wild-type- and Omicron-BA.1-specific IgG concentrations were comparable between younger and older adults, although BA.1-specific responses were consistently significantly lower than wild-type-specific responses in both groups. Wild-type- and BA.1-specific IgG concentrations declined at similar rates in COVID-19-naive younger and older adults, with median half-lives ranging from 69 to 78 days. Antiviral antibody functions declined substantially over time in COVID-19-naive individuals, particularly in older adults: by 6 months, BA.1-specific neutralization was undetectable in 96% of older adults, versus 56% of younger adults. Severe acute respiratory syndrome coronavirus 2 infection, experienced by 38 participants, boosted IgG levels and neutralization above those induced by vaccination alone. Nevertheless, BA.1-specific neutralization remained significantly lower than wild-type, with BA.5-specific neutralization lower still. Higher Omicron BA.1-specific neutralization 1 month after third dose was an independent correlate of lower SARS-CoV-2 infection risk.ConclusionsResults underscore the immune benefits of the third COVID-19 mRNA vaccine dose in adults of all ages and identify vaccine-induced Omicron-specific neutralization as a correlate of protective immunity. Systemic antibody responses and functions however, particularly Omicron-specific neutralization, decline rapidly in COVID-19-naive individuals, particularly in older adults, supporting the need for additional booster doses.

BackgroundLimited data exist regarding longer-term antibody responses following three-dose COVID-19 vaccination, and the impact of a first SARS-CoV-2 infection during this time, in people living with HIV (PLWH) receiving suppressive antiretroviral therapy (ART). We quantified wild-type-(WT), Omicron BA.1- and Omicron BA.5-specific responses up to six months post-third dose in 64 PLWH and 117 controls who remained COVID-19-naive or experienced their first SARS-CoV-2 infection during this time.DesignLongitudinal observational cohort.MethodsWe quantified WT- and Omicron-specific Anti-Spike receptor-binding domain IgG concentrations, ACE2 displacement activities and live virus neutralization at one, three and six months post-third vaccine dose.ResultsThird doses boosted all antibody measures above two-dose levels, but BA.1-specific responses remained significantly lower than WT-specific ones, with BA.5-specific responses lower still. Serum IgG concentrations declined at similar rates in COVID-19-naive PLWH and controls post-third dose (median WT- and BA.1-specific half-lives were between 66-74 days for both groups). Antibody function also declined significantly yet comparably between groups: six months post-third dose, BA.1-specific neutralization was undetectable in >80% of COVID-19 naive PLWH and >90% of controls. Breakthrough SARS-CoV-2 infection boosted antibody concentrations and function significantly above vaccine-induced levels in both PLWH and controls, though BA.5-specific neutralization remained significantly poorer than BA.1 even post-breakthrough.ConclusionsFollowing three-dose COVID-19 vaccination, antibody response durability in PLWH receiving ART is comparable to controls. PLWH also mounted strong responses to breakthrough infection. Due to temporal response declines however, COVID-19-naive individuals, regardless of HIV status, would benefit from a fourth dose within 6 months of their third.

BackgroundLonger-term immune response data after three doses of COVID-19 mRNA vaccine remain limited, particularly among older adults and following Omicron breakthrough infection.MethodsWe quantified wild-type- and Omicron-specific serum IgG levels, ACE2 displacement activities and live virus neutralization up to six months post-third dose in 116 adults aged 24-98 years who remained COVID-19-naïve or experienced their first SARS-CoV-2 infection during this time.ResultsAmong 78 participants who remained COVID-19-naïve throughout follow-up, wild-type- and Omicron BA.1-specific IgG concentrations were comparable between younger and older adults, though BA.1-specific responses were consistently significantly lower than wild-type-specific responses in both groups. Wild-type- and BA.1-specific IgG concentrations declined at similar rates among COVID-19-naïve younger and older adults, with median half-lives ranging from 69-78 days. Antiviral antibody function declined substantially over time in COVID-19-naïve individuals, particularly older adults: by six months, BA.1-specific neutralization was undetectable in 96% of older adults, versus 56% of younger adults. SARS-CoV-2 infection, experienced by 38 participants, boosted IgG levels and neutralization above those induced by vaccination alone. Nevertheless, BA.1-specific neutralization remained significantly lower than wild-type, with BA.5-specific neutralization lower still.ConclusionsOur findings underscore the immune benefits of third COVID-19 mRNA vaccine doses in adults of all ages, but rapid decline of Omicron-specific neutralization activity in COVID-19-naïve individuals, particularly among older adults, demonstrates the need for fourth doses within 3-6 months to maintain systemic responses. Individuals who experienced SARS-CoV-2 breakthrough infection post-third vaccine dose however can likely delay a fourth dose beyond this timeframe.

BackgroundLonger-term humoral responses to two-dose COVID-19 vaccines remain incompletely characterized in people living with HIV (PLWH), as do initial responses to a third dose.MethodsWe measured antibodies against the SARS-CoV-2 spike protein receptor-binding domain, ACE2 displacement and viral neutralization against wild-type and Omicron strains up to six months following two-dose vaccination, and one month following the third dose, in 99 PLWH receiving suppressive antiretroviral therapy, and 152 controls.ResultsThough humoral responses naturally decline following two-dose vaccination, we found no evidence of lower antibody concentrations nor faster rates of antibody decline in PLWH compared to controls after accounting for sociodemographic, health and vaccine-related factors. We also found no evidence of poorer viral neutralization in PLWH after two doses, nor evidence that a low nadir CD4+ T-cell count compromised responses. Post-third-dose humoral responses substantially exceeded post-second-dose levels, though anti-Omicron responses were consistently weaker than against wild-type.Nevertheless, post-third-dose responses in PLWH were comparable to or higher than controls. An mRNA-1273 third dose was the strongest consistent correlate of higher post-third-dose responses.ConclusionPLWH receiving suppressive antiretroviral therapy mount strong antibody responses after two- and three-dose COVID-19 vaccination. Results underscore the immune benefits of third doses in light of Omicron.

Background. Two-dose mRNA vaccines reduce COVID-19 related hospitalization and mortality, but immune protection declines over time. As such, third vaccine doses are now recommended, particularly for older adults. We examined immune response durability up to six months after two vaccine doses, and immunogenicity after a third vaccine dose, in 151 adults ranging in age from 24 to 98 years. Methods. Specimens were collected from 81 healthcare workers (median age 41 years), 56 older adults (median 78 years) and 14 COVID-19 convalescent individuals (median 48 years), at one, three and six months following the second vaccine dose, and from 15 HCW, 28 older adults and 3 convalescent individuals at one month following a third vaccine dose. Binding antibodies to the SARS-CoV-2 spike receptor binding domain were quantified using a commercial immunoassay. Virus neutralizing activity was assessed using a live SARS-CoV-2 infection assay. Results. Compared to healthcare workers, older adults displayed ~0.3 log10 lower peak binding antibodies one month after the second vaccine dose (p

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains a global public health crisis. The reduced efficacy of therapeutic monoclonal antibodies against emerging SARS-CoV-2 variants of concern (VOCs), such as omicron BA.5 subvariants, has underlined the need to explore a novel spectrum of antivirals that are effective against existing and evolving SARS-CoV-2 VOCs. To address the need for novel therapeutic options, we applied cell-based high-content screening to a library of natural products (NPs) obtained from plants, fungi, bacteria, and marine sponges, which represent a considerable diversity of chemical scaffolds. The antiviral effect of 373 NPs was evaluated using the mNeonGreen (mNG) reporter SARS-CoV-2 virus in a lung epithelial cell line (Calu-3). The screening identified 26 NPs with half-maximal effective concentrations (EC

Humoral responses to COVID-19 vaccines in people living with HIV (PLWH) remain incompletely understood. We measured circulating antibodies against the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein, ACE2 displacement and live viral neutralization activities one month following the first and second COVID-19 vaccine doses in 100 adult PLWH and 152 controls. All PLWH were receiving suppressive antiretroviral therapy, with median CD4+ T-cell counts of 710 (IQR 525-935) cells/mm3. Nadir CD4+ T-cell counts ranged as low as 3. After adjustment for sociodemographic, health and vaccine-related variables, HIV infection was significantly associated with 0.2 log10 lower anti-RBD antibody concentrations (p=0.03) and ∼11% lower ACE2 displacement activity (p=0.02), but not lower viral neutralization (p=0.1) after one vaccine dose. Following two doses however, HIV was no longer significantly associated with the magnitude of any response measured. Rather, older age, a higher burden of chronic health conditions, and having received two ChAdOx1 doses (versus a heterologous or dual mRNA vaccine regimen) were independently associated with lower responses. After two vaccine doses, no significant correlation was observed between the most recent or nadir CD4+ T-cell counts and vaccine responses in PLWH. These results suggest that PLWH with well-controlled viral loads on antiretroviral therapy and CD4+ T-cell counts in a healthy range will generally not require a third COVID-19 vaccine dose as part of their initial immunization series, though other factors such as older age, co-morbidities, vaccine regimen type, and durability of vaccine responses will influence when this group may benefit from additional doses. Further studies of PLWH who are not receiving antiretroviral treatment and/or who have low CD4+ T-cell counts are needed.

BackgroundmRNA vaccines reduce COVID-19 incidence and severity, but the durability of vaccine-induced immune responses, particularly among the elderly, remains incompletely characterized.MethodsAnti-spike RBD antibody titers, ACE2 competition and virus neutralizing activities were longitudinally assessed in 151 healthcare workers and older adults (overall aged 24-98 years) up to three months after vaccination.ResultsOlder adults exhibited lower antibody responses after one and two vaccine doses for all measures. In multivariable analyses correcting for sociodemographic, chronic health and vaccine-related variables, age remained independently associated with all response outcomes. The number of chronic health conditions was additionally associated with lower binding antibody responses after two doses, and male sex with lower ACE2 competition activity after one dose. Responses waned universally at three months after the second dose, but binding antibodies, ACE2 competition and neutralizing activities remained significantly lower with age. Older adults also displayed reduced ability to block ACE2 binding by the Delta variant.ConclusionsThe humoral immune response to COVID-19 mRNA vaccines is significantly weaker with age, and universally wanes over time. This will likely reduce antibody-mediated protection against SARS-CoV-2 and the Delta variant as the pandemic progresses. Older adults may benefit from additional immunizations as a priority.

Background The magnitude and durability of immune responses to coronavirus disease 2019 (COVID-19) mRNA vaccines remain incompletely characterized in the elderly. Methods Anti-spike receptor-binding domain (RBD) antibodies, angiotensin-converting enzyme 2 (ACE2) competition, and virus neutralizing activities were assessed in plasma from 151 health care workers and older adults (range, 24–98 years of age) 1 month following the first vaccine dose, and 1 and 3 months following the second dose. Results Older adults exhibited significantly weaker responses than younger health care workers for all humoral measures evaluated and at all time points tested, except for ACE2 competition activity after 1 vaccine dose. Moreover, older age remained independently associated with weaker responses even after correction for sociodemographic factors, chronic health condition burden, and vaccine-related variables. By 3 months after the second dose, all humoral responses had declined significantly in all participants, and remained significantly lower among older adults, who also displayed reduced binding antibodies and ACE2 competition activity towards the Delta variant. Conclusions Humoral responses to COVID-19 mRNA vaccines are significantly weaker in older adults, and antibody-mediated activities in plasma decline universally over time. Older adults may thus remain at elevated risk of infection despite vaccination.

The SARS-CoV-2 pandemic has highlighted the weaknesses of relying on single-use mask and respirator personal protective equipment (PPE) and the global supply chain that supports this market. There have been no major innovations in filter technology for PPE in the past two decades. Non-woven textiles used for filtering PPE are single-use products in the healthcare environment; use and protection is focused on preventing infection from airborne or aerosolized pathogens such as Influenza A virus SARS-CoV-2. Recently, C–H bond activation under mild and controllable conditions was reported for crosslinking commodity aliphatic polymers such as polyethylene and polypropylene. Significantly, these are the same types of polymers used in PPE filtration systems. In this report, we take advantage of this C–H insertion method to covalently attach a photosensitizing zinc-porphyrin to the surface of a melt-blow non-woven textile filter material. With the photosensitizer covalently attached to the surface of the textile, illumination with visible light was expected to produce oxidizing 1O2/ROS at the surface of the material that would result in pathogen inactivation. The filter was tested for its ability to inactivate Influenza A virus, an enveloped RNA virus similar to SARS-CoV-2, over a period of four hours with illumination of high intensity visible light. The photosensitizer-functionalized polypropylene filter inactivated our model virus by 99.99% in comparison to a control.

Marek's disease (MD) vaccines are unique in their capability to prevent MD lymphomas as early as a few days after vaccination, despite the fact that they do not eliminate virulent viruses from the host. To help understand the mechanism behind this unique MD vaccine effect, we compared the expression of MDV oncoprotein Meq among CD4+ T cells between vaccinated and unvaccinated birds. Chickens were vaccinated by an MD vaccine, herpesvirus of turkeys, and then challenged by a recombinant virulent MDV that expresses green fluorescent protein simultaneously with Meq. We found significantly fewer Meq-expressing CD4+ T cells appeared in peripheral blood mononuclear cells (PBMC) of the vaccinated birds compared to the unvaccinated birds as early as one week after the virulent virus challenge. In contrast, the quantity of virulent MDV genome remained similar in Meq- PBMC in both vaccinated and unvaccinated birds. Our results suggest that MD vaccination affects the dynamics of Meq-expressing, possibly transformed, cells while impact on the overall infection in the Meq- cells was not significant.

Cell-based immunotherapy is being evaluated in various types of cancer and it is one of the most rapidly growing and promising areas of cancer research. Tumor-infiltrating leukocytes (TILs) consist of highly diverse leukocyte subsets with major roles in cancer immune surveillance. Due to their relatively low frequency, tumor heterogeneity, and the abundance of tissue debris in tumor samples, it is difficult to isolate or analyze TILs with sensitivity and precision. To address this challenge, we have developed a simple method for isolating CD45+ TILs from mouse tumors. Performance was evaluated in three commonly used mouse models, namely the B16 melanoma, CT26 colon carcinoma, and 4T1 mammary tumor models. Solid tumors were induced by subcutaneous implantation of B16, CT26.WT, and 4T1 cancer cell lines into syngeneic recipients. Starting with a single-cell suspension, TILs from tumor samples were labeled with an antibody complex that links CD45+ cells to magnetic particles, then separated using an EasySep™ magnet. Using this method, TILs were enriched from 17.5 +/− 5.8% to 90.1 +/− 6.0% (n = 13) from B16 tumors, 27.9 +/− 9.4% to 74.2 +/− 12.3 % (n = 9) from CT26 tumors, and 39.5 +/− 8.0% to 87.5 +/− 3.7% (n = 6) from 4T1 tumors. The protocol can be easily modified to achieve higher purity or recovery as required by adjusting the addition volume of the antibody complex or particles. Importantly, major immune subsets including T cells, B cells, and myeloid cells are recovered after isolation. The EasySep™ Mouse CD45 TIL Isolation Kit allows researchers to isolate leukocytes from tumors with ease, improving the TIL downstream workflow. Furthering our understanding of TILs will be essential for developing effective immunotherapeutic strategies.