Biology subjects

Fontaine, J.

Publications and source records attributed to Fontaine, J..

3 recordsLinked to original sources

bioRxiv2026

Neutralizing vaccination against viral interleukin-6 from a primate rhadinovirus

Herpesviruses are ancient viruses that devote a significant fraction of their protein-coding potential to interference with host immunity. Diverse herpesviruses encode proteins with similarity to host MHC molecules, interferon regulatory factors, complement regulators, G-protein coupled receptors, chemokines, and cytokines. Certain gammaherpesviruses, including Kaposi sarcoma-associated herpesvirus (KSHV) and rhesus rhadinovirus (RRV), encode viral cytokines similar to host IL-6, called viral IL-6 (vIL-6). The potential of vIL-6 to act as a protective vaccine antigen against these rhadinoviruses remains under-explored. We isolated a new RRV strain, which encodes virion surface proteins similar to those of previous isolates and a vIL-6 that is nearly identical. We found that, although unmodified vIL-6 is a poor immunogen eliciting low neutralizing titers, vIL-6-Fc fusion protein elicits high-titer responses after either one or two doses. We detected no adverse effects related to cytokine activity, nor interference with concomitantly administered vaccine against the RRV glycoprotein B. Our results demonstrate an approach for eliciting neutralizing antibodies against a highly conserved viral protein that contributes to rhadinovirus persistence and oncogenesis.

immunology↗

bioRxiv2023

Enteric Populations of Escherichia coli are Likely to be Resistant to Phages Due to O Antigen Production

Metagenomic data provide evidence that bacteriophage (phage) abound in the enteric microbiomes of humans. However, the contribution of these viruses in shaping the bacterial composition of the gut microbiome and how these phages are maintained remains unclear. We performed experiments with 751 combinations of 54 Escherichia coli and 9 phage isolates from four fecal microbiota transplantation (FMT) doses and 5 laboratory phages as samples of non-dysbiotic human enteric microbiota. We also developed a mathematical model of the population and evolutionary dynamics of bacteria and phage. Our experiments predict that as a consequence of the production of the O-antigen, most of the E. coli in the human enteric microbiome will be resistant to infections with the array of co-occurring phages. Our modeling suggests that phages are maintained in these enteric communities due to the high rates of transition between the resistant and sensitive states resulting from O-antigen production or spontaneous O-antigen loss, respectively. Based on our observations and predictions from this theory, we postulate that the phage found in the human gut are likely to play little role shaping the strain composition of E. coli of healthy individuals. Although we only investigated E. coli, the mechanism of resistance described here is shared among most of the Gram-negative bacteria. Extended AbstractEvidence is provided that as a consequence of O-antigen-mediated resistance, the genetically diverse array of bacteriophage in the gut microbiome of humans play little or no role in determining the densities and distribution of genetically diverse strain E. coli in this habitat. Our mathematical model predicts, and our experiments support the hypothesis that the phage present in the gut microbiome are maintained by replication on the minority of sensitive bacteria generated by the leakiness of O-antigen-mediated resistance.

microbiology↗

bioRxiv2023

SIV clearance from neonatal macaques following transient CCR5 depletion

SUMMARY PARAGRAPHTreatment of people with HIV (PWH) with antiretroviral therapy (ART) results in sustained suppression of viremia, but HIV persists indefinitely as integrated provirus in CD4-expressing cells. Intact persistent provirus, the "rebound competent viral reservoir" (RCVR), is the primary obstacle to achieving a cure. Most variants of HIV enter CD4+ T cells by binding to the chemokine receptor, CCR5. The RCVR has been successfully depleted only in a handful of PWH following cytotoxic chemotherapy and bone marrow transplantation from donors with a mutation in CCR5. Here we show that long-term SIV remission and apparent cure can be achieved for infant macaques via targeted depletion of potential reservoir cells that express CCR5. Neonatal rhesus macaques were infected with virulent SIVmac251, then treated with ART beginning one week after infection, followed by treatment with either a CCR5/CD3-bispecific or a CD4-specific antibody, both of which depleted target cells and increased the rate of plasma viremia decrease. Upon subsequent cessation of ART, three of seven animals treated with CCR5/CD3-bispecific antibody rebounded quickly and two rebounded 3 or 6 months later. Remarkably, the other two animals remained aviremic and efforts to detect replication-competent virus were unsuccessful. Our results show that bispecific antibody treatment can achieve meaningful SIV reservoir depletion and suggest that functional HIV cure might be achievable for recently infected individuals having a restricted reservoir.

immunology↗