Distinct SARS-CoV-2 specific NLRP3 and IL-1ß responses in T cells of aging patients during acute COVID-19 infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes Coronavirus Disease 2019 (COVID-19) that presents with varied clinical manifestations ranging from asymptomatic or mild infections and pneumonia to severe cases associated with cytokine storm, acute respiratory distress syndrome (ARDS), and even death. The underlying mechanisms contributing to these differences are unclear, although exacerbated inflammatory sequelae resulting from infection have been implicated. While advanced aging is a known risk factor, the precise immune parameters that determine the outcome of SARS-CoV-2 infection in elderly individuals are not understood. Here, we found aging-associated (age ≥61) intrinsic changes in T cell responses when compared to those from individuals aged ≤ 60, even among COVID-positive patients with mild symptoms. Specifically, when stimulated with SARS-CoV-2 peptides in vitro, peripheral blood mononuclear cell (PBMC) CD4+ and CD8+ T cells from individuals aged ≥61 showed a diminished capacity to produce IFN-γ and IL-1ß. Although they did not have severe disease, aged individuals also showed a higher frequency of PD-1+ cells and significantly diminished IFN-γ/PD-1 ratios among T lymphocytes upon SARS-CoV-2 peptide stimulation. Impaired T cell IL-1ß expression coincided with reduced NLRP3 levels in T lymphocytes. However, the expression of these molecules was not affected in the monocytes of individuals aged ≥61. Together, these data reveal SARS-CoV-2-specific CD4+ and CD8+ T-cell intrinsic cytokine alterations in the individuals older than 61 and may provide new insights into dysregulated COVID-directed immune responses in the elderly.

Rheumatoid arthritis and older age are associated with lower humoral and cellular immune response to primary series COVID-19 mRNA vaccine.

OBJECTIVE: People with autoimmune disease have worse COVID-19 infection-related outcomes, lower antibody responses to COVID-19 vaccine, and higher rates of breakthrough infection. Immunosuppressive medications used to treat rheumatoid arthritis (RA) are associated with lower COVID-19 vaccine responses, though independent contributions of comorbidities, T-cell immunity, and age are less clear. We sought to test the hypothesis that RA, immunosuppressive medications used to treat RA, and older age, contribute to reduced B and T cell response to COVID-19 vaccine. METHODS: We evaluated serum samples, taken the day of 1st vaccine dose, the day of 2nd dose, 2-6 weeks after 2nd dose, 7-12 weeks after 2nd dose, 13-24 weeks after 2nd dose, and 2-6 weeks after the 3rd dose, for anti-spike IgG and neutralizing antibody levels to Wuhan and Omicron BA.1 and peripheral blood mononuclear cells (PBMC) for spike-specific IFN-γ and IL-2 production by ELISPOT assay in 46 RA and 101 non-autoimmune control participants before and after the primary series COVID-19 mRNA vaccination. RESULTS: RA participants had lower spike-specific IgG and Wuhan-strain neutralizing antibody levels 2-6 weeks compared to controls after the second dose of primary vaccine series. Neutralizing antibody levels against Omicron BA.1 were low in both groups. IFN-γ production correlated with Wuhan neutralizing antibody levels, while older age negatively correlated with spike-specific IL-2, IFN-γ and IgG. Lower antibody levels were associated with older age, RA status, and medication usage, while lower T cell responses were associated primarily with older age. CONCLUSIONS: These data indicate lower COVID-19 mRNA vaccine-induced antibody levels in persons with RA compared to individuals without RA, likely partially attributable to immune suppressive medications. At the same time, older age is associated with lower antibody and cellular immune response to COVID-19 vaccines.

High Seropositivity Rate of Neutralizing Antibodies to Astrovirus VA1 in Human Populations.

Astroviruses are common pathogens of the human gastrointestinal tract, but they have been recently identified from cases of fatal meningoencephalitis. Astrovirus VA1 is the most frequently detected astrovirus genotype from cases of human encephalitis, but the prevalence of neutralizing antibodies to VA1 in human sera is unknown. We developed a focus reduction neutralization assay (FRNT) for VA1 and measured the seroprevalence of neutralizing antibodies from two cohorts of adult and pediatric serum samples: (i) an age-stratified cohort from St. Louis, MO, collected from 2007 to 2008 and (ii) a cohort from the Peruvian Amazonian River Basin collected in the late 1990s. In the St. Louis cohort, the lowest seropositivity rate was in children 1 year of age (6.9%), rising to 63.3% by ages 9 to 12, and 76.3% of adults ≥20 years were positive. The Peruvian Amazon cohort showed similar seropositivity rates across all ages, with individuals under age 20 having a rate of 75%, while 78.2% of adults ≥20 years were seropositive. In addition, we also identified the presence neutralizing antibodies to VA1 from commercial lots of intravenous immunoglobulin (IVIG). Our results demonstrate that a majority of humans are exposed to VA1 by adulthood, with the majority of infections occurring between 2 and 9 years of age. In addition, our results indicate that VA1 has been circulating in two geographically and socioeconomically divergent study cohorts over the past 20 years. Nonetheless, a significant proportion of the human population lacks neutralizing immunity and remains at risk for acute infection. IMPORTANCE Astroviruses are human pathogens with emerging disease associations, including the recent recognition of their capacity to cause meningoencephalitis. Astrovirus VA1 is the most commonly identified astrovirus genotype from cases of human encephalitis, but it is unknown what percentage of the human population has neutralizing antibodies to VA1. We found that 76.3 to 78.2% of adult humans ≥20 years of age in two geographically and socioeconomically distinct cohorts are seropositive for VA1, with the majority of infections occurring between 2 and 9 years of age. These results demonstrate that VA1 has been circulating in human populations over the past 2 decades and that most humans develop neutralizing antibodies against this virus by adulthood. However, a subset of humans lack evidence of neutralizing antibodies and are at risk for diseases caused by VA1, including encephalitis.

Antiviral activity of ribavirin and favipiravir against human astroviruses.

BACKGROUND: Recent recognition of invasive astrovirus infections, including encephalitis and viremia in humans, have highlighted the need for effective anti-astrovirus therapeutics. However, there is a paucity of data regarding the in vitro activity of broad-spectrum RNA antivirals against astroviruses, including ribavirin and favipiravir. OBJECTIVES: We quantified the EC50 values for ribavirin and favipiravir against two human astrovirus strains, astrovirus VA1 (VA1) and human astrovirus 4 (HAstV4). STUDY DESIGN: Caco-2 cells were infected with VA1 or HAstV4 in the presence of ribavirin or favipiravir (dose range 0.1-1000 µM), and the cells were maintained in media containing the drugs for 72 h. Viral RNA was extracted and quantified by qRT-PCR. As a surrogate for cytotoxicity, cellular adenosine triphosphate (ATP) from each drug treatment was also measured. RESULTS: VA1 replication was inhibited 10-100-fold by both ribavirin (EC50 = 154 µM) and favipiravir (EC50 = 246 µM). In contrast, ribavirin inhibited HAstV4 replication (EC50 = 268 µM) but favipiravir only reduced replication by 44% at the highest dose. Mild reductions in ATP (17-31%) was only observed at the highest concentration of ribavirin (1000 µM) and no significant decrease in ATP was detected for any concentration of favipiravir. CONCLUSIONS: Ribavirin inhibited both human astrovirus species and favipiravir was only active against VA1. In the future, the in vivo efficacy of these drugs could be tested with development of an animal model of human astrovirus infection.