Biology subjects

Jesudhasan, P. R.

Publications and source records attributed to Jesudhasan, P. R..

3 recordsLinked to original sources

bioRxiv2018

Characterization of a thermal stable poliovirus mutant reveals distinct mechanisms of virion stabilization

Enteric viruses, including poliovirus, are spread by the fecal-oral route. In order to persist and transmit to a new host, enteric virus particles must remain stable once they are in the environment. Environmental stressors such as heat and disinfectants can inactivate virus particles and prevent viral transmission. It has been previously demonstrated that bacteria or bacterial surface glycans can enhance poliovirus virion stability and limit inactivation from heat or bleach. While investigating the mechanisms underlying bacterial-enhanced virion thermal stability, we identified and characterized a poliovirus mutant with increased resistance to heat inactivation. This poliovirus mutant, M132V, harbors a single amino acid change in the VP1 capsid-coding that is sufficient to confer heat resistance. M132V was comparable to wild-type virus for replication in vitro, as well as for replication and pathogenesis in orally-inoculated mice. Although the M132V virus was stable in the absence of bacteria or feces at most temperatures, M132V virus was stabilized by feces at very high temperatures. Additionally, the M132V virus does not have enhanced stability during bleach treatment, suggesting that thermal and bleach inactivation mechanisms are separable. Our results suggest that different mechanisms underlie virion stabilization by bacteria and the M132V mutation. Overall, this work sheds light on factors that influence virion stability.\n\nIMPORTANCEViruses spread by the fecal-oral route need to maintain viability in the environment to ensure transmission. Previous work indicated that bacteria and bacterial surface polysaccharides can stabilize viral particles and enhance transmission. To explore factors that influence viral particle stability, we isolated a mutant poliovirus that is heat resistant. This mutant virus does not require feces for stability at most temperatures, but can be stabilized by feces at very high temperatures. Even though the mutant virus is heat resistant, it is susceptible to inactivation by treatment with bleach. This work provides insight into how viral particles maintain infectivity in the environment.

microbiology↗

bioRxiv2017

Bacteria facilitate viral co-infection of mammalian cells and promote genetic recombination

Intestinal bacteria promote infection of several mammalian enteric viruses, but the mechanisms and consequences are unclear. We screened a panel of 41 bacterial strains as a platform to determine how different bacteria impact enteric viruses. We found that most bacterial strains bound poliovirus, a model enteric virus. Given that each bacterium bound multiple virions, we hypothesized that bacteria may deliver multiple viral genomes to a mammalian cell even when very few virions are present, such as during the first replication cycle after inter-host transmission. We found that exposure to certain bacterial strains increased viral co-infection even when the ratio of virus to host cells was low. Bacteria-mediated viral co-infection correlated with bacterial adherence to cells. Importantly, bacterial strains that induced viral co-infection facilitated viral fitness restoration through genetic recombination. Thus, bacteria-virus interactions may increase viral fitness through viral recombination at initial sites of infection, potentially limiting abortive infections.

microbiology↗

bioRxiv2017

Plaques formed by mutagenized viral populations have elevated co-infection frequencies

The plaque assay is a common technique used to measure virus concentrations and is based upon the principle that each plaque represents a single infectious unit. As such, plaque number is expected to correlate linearly with the virus dilution plated and each plaque should be formed by a single founder virus. Here, we examined whether more than one virus can contribute to plaque formation. By using genetic and phenotypic assays with genetically marked polioviruses, we found that multiple parental viruses are present in 5-7% of plaques, even at an extremely low multiplicity of infection. We demonstrated through visual and biophysical assays that, like many viral stocks, our viral stocks contain both single particles and aggregates. These data suggest that aggregated virions are capable of inducing co-infection and chimeric plaque formation. In fact, inducing virion aggregation via exposure to low pH increased co-infection in a flow cytometry-based assay. We hypothesized that plaques generated by viruses with high mutation loads may have higher co-infection frequencies due to fitness restoring processes such as complementation and recombination. Indeed, we found that co-infection frequency correlated with mutation load, with 17% chimeric plaque formation for heavily mutagenized viruses. Importantly, the frequency of chimeric plaques may be underestimated by up to three-fold, since co-infection with the same parental virus cannot be scored in our assay. This work indicates that more than one virus can contribute to plaque formation and that co-infection may assist plaque formation in situations where the amount of genome damage is high.

microbiology↗