Biology subjects

Kohlmeier, J.

Publications and source records attributed to Kohlmeier, J..

5 recordsLinked to original sources

bioRxiv2026

Distinct Longitudinal Antibody Responses Following Primary Influenza Infection or Vaccination in Infants: A Prospective Birth Cohort Study

The longitudinal effects of initial influenza exposure on the magnitude, persistence, and antigen specificity of antibody responses during infancy remain incompletely understood. We investigated humoral antibody responses following primary influenza infection or seasonal vaccination in a prospective US birth cohort with weekly respiratory surveillance for influenza infection. Influenza-specific serum IgG binding to H1 and H3 haemagglutinin (HA) antigens, HA inhibition (HAI), and live-virus neutralizing antibody responses were assessed longitudinally. To minimize influence of maternally derived antibodies, analyses of primary exposure responses were restricted to infants for whom influenza-specific maternal antibodies had declined below the assay detection limit before exposure. Antibody responses were compared following primary infection and vaccination and examined after subsequent annual vaccination. We found that maternal influenza-specific IgG declined rapidly during early infancy. Among infants without detectable pre-exposure influenza-specific antibodies, primary influenza infection was associated with greater post-exposure antibody responses and less measurable decline over follow-up than primary vaccination. These groups differed in age, calendar season, and exposure characteristics, limiting direct attribution of these differences to route of exposure. In infants with previous influenza infection followed by vaccination, responses after subsequent vaccination initially showed greater binding to the previously infecting subtype among the tested HA antigens. With repeated vaccination, responses became more distributed across the tested antigens. Our findings reveal differences in the magnitude, persistence, and antigen specificity of antibody responses according to the nature and sequence of influenza exposure. By prospectively capturing early-life exposures, this study provides longitudinal evidence linking exposure history to subsequent humoral antibody responses.

immunology↗

bioRxiv2025

Quantifying the role of pre-existing tissue resident cellular immunity in limiting respiratory virus transmission

Viral transmission from infected donors to uninfected recipients is the key event underlying the spread of viral pathogens at the level of a host population. Successful viral transmission from a donor to a recipient depends on several factors including the infectiousness of the donor. Donor infectiousness in turn can depend on the viral kinetics and viral load of the donor, donor behavior and symptoms, and donor immunity. Here, we use a mouse model of murine respirovirus (otherwise known as Sendai virus SeV) infection to quantitatively explore donor determinants of respiratory virus transmission. The experimental transmission studies we analyze are specifically designed to address the effect that pre-existing donor immunity may have on transmission potential by studying SeV transmission from both immunized and control (placebo-immunized) donors to naive recipients. We specifically focus on the impact of tissue resident memory (TRM) CD8 T cells on donor transmission potential by considering immunization strategies that primarily generate CD8 T cell immunity. Through quantitative analyses of these experiments, we find that pre-existing CD8 TRMs act to reduce donor transmission potential. This reduction can be in part explained by a reduction in total infection load in immunized donors. However, even once differences in infection load between immunized and control donors are accounted for, immunized donors still have reduced infectiousness relative to control donors. We explore possible reasons for this unexpected pattern using a mathematical model that integrates within-host viral dynamics and between-host transmission occurrences. Analysis of model simulations, along with observations from knock-out experiments, suggests that interferon gamma (IFN-{gamma}) may be partly responsible for the observed differences in infectiousness between control and pre-immune donors. Future experimental transmission studies should consider measuring IFN-{gamma} levels when interpreting transmission outcomes in the context of host immunity.

immunology↗

bioRxiv2024

CD4+ and CD8+ T cells are required to prevent SARS-CoV-2 persistence in the nasal compartment

SARS-CoV-2 is the causative agent of COVID-19 and continues to pose a significant public health threat throughout the world. Following SARS-CoV-2 infection, virus-specific CD4+ and CD8+ T cells are rapidly generated to form effector and memory cells and persist in the blood for several months. However, the contribution of T cells in controlling SARS-CoV-2 infection within the respiratory tract are not well understood. Using C57BL/6 mice infected with a naturally occurring SARS-CoV-2 variant (B.1.351), we evaluated the role of T cells in the upper and lower respiratory tract. Following infection, SARS-CoV-2-specific CD4+ and CD8+ T cells are recruited to the respiratory tract and a vast proportion secrete the cytotoxic molecule Granzyme B. Using antibodies to deplete T cells prior to infection, we found that CD4+ and CD8+ T cells play distinct roles in the upper and lower respiratory tract. In the lungs, T cells play a minimal role in viral control with viral clearance occurring in the absence of both CD4+ and CD8+ T cells through 28 days post-infection. In the nasal compartment, depletion of both CD4+ and CD8+ T cells, but not individually, results in persistent and culturable virus replicating in the nasal compartment through 28 days post-infection. Using in situ hybridization, we found that SARS-CoV-2 infection persisted in the nasal epithelial layer of tandem CD4+ and CD8+ T cell-depleted mice. Sequence analysis of virus isolates from persistently infected mice revealed mutations spanning across the genome, including a deletion in ORF6. Overall, our findings highlight the importance of T cells in controlling virus replication within the respiratory tract during SARS-CoV-2 infection.

immunology↗

bioRxiv2022

Memory CD4 T cell subset organization in the female reproductive tract is regulated via the menstrual cycle through CCR5 signaling

Despite their importance for immunity against sexually transmitted infections (STIs), the composition of the female reproductive tract (FRT) memory CD4 T cell population in response to changes in the local tissue environment during the menstrual cycle remains poorly defined. Here we show that across humans, non-human primates (NHP), and mice, FRT CD4 T cells comprise distinct subsets corresponding to migratory memory (TMM) and resident memory (TRM) cells. TMM display tissue-itinerant trafficking characteristics, restricted FRT tissue distribution, with distinct transcriptional properties and effector responses to infection. CD4 T cell subset fluctuations synchronized with cycle-driven proinflammatory changes within the local tissue environment and oral administration of a CCR5 antagonist inhibited cycle phase-specific migratory T cell surveillance. This study provides novel insights into the dynamic nature of FRT memory CD4 T cells and identifies the menstrual cycle as a key regulator of memory T cell defense at the site of STI exposure. SummaryThe menstrual cycle regulates memory T cell surveillance.

immunology↗

bioRxiv2018

Why Are CD8 T Cell Epitopes of Human Influenza A Virus Conserved?

The high-degree conservation of CD8 T cell epitopes of influenza A virus (IAV) may allow T cell-inducing vaccines effective across different strains and subtypes. This conservation is not fully explained by functional constraint, since additional mutation(s) can compensate the replicative fitness loss of IAV escape-variant. Here, we propose three additional mechanisms that contribute to the conservation of CD8 T cell epitopes of IAV. First, influenza-specific CD8 T cells may protect predominantly against severe pathology rather than infection and may only have a modest effect on transmission. Second, polymorphism of human MHC-I gene restricts the advantage of an escape-variant to only a small fraction of human population, who carry the relevant MHC-I alleles. Finally, infection with CD8 T cell-escapevariants may result in compensatory increase in the responses to other epitopes of IAV. A combination of population genetics and epidemiological models is used to examine how the interplay between these mechanisms affects the rate of invasion of IAV escape-variants. We conclude that the invasion of an escape-variant will be very slow with a timescale of decades or longer, even if the escape-variant does not have a replicative fitness loss. Our results suggest T cell-inducing vaccines may not engender the rapid evolution of IAV and serve as a foundation for future modeling works on the long-term effectiveness and impacts of T cell-inducing influenza vaccines. (Word count: 221)\n\nImportanceUniversal influenza vaccines against the conserved epitopes of influenza A virus have been proposed to minimize the burden of seasonal outbreaks and prepare for the pandemics. However, it is not clear to which extent the T cell-inducing vaccines will select for viruses that escape the T cell responses. Our mathematical models suggest how the nature of CD8 T cell protection contributes to the conservation of the CD8 T cell epitopes of influenza A virus. Also, it points out the essential biological parameters and questions that need addressing by future experimental works. (Word count: 91)

immunology↗