Abstract

Cross Talk Between Viruses and EV Biogenesis

Fatah Kashanchi, Professor, George Mason University

Most RNA and DNA viruses package and release their products (DNA, RNA, proteins) in EVs to avoid detection by the host immune system. In the current study we have addressed two main questions related to timing of the EV vs. virus release using HIV-1 as a model system, and have further found a new method of isolating viral populations that have never been described before. To date, it is not clear whether there is a timing difference between EV and virion release from infected cells. Here, we found that EVs precede the secretion of viral particles at 6 hrs post-transcriptional activation and release. This early EV release could shed light on how the contents of EVs are able to increase the susceptibility of viral infection, perhaps by priming the environment prior to viral egress or altering the progression of the cell cycle in recipient cells. We also have found that when separating EVs using differential ultracentrifugation, size exclusion chromatography or simple size filtration, there are at least three distinct sizes and functional viruses when using HIV-1 as a model system.  Validation of the data was performed utilizing blocking infectivity with broadly neutralizing antibodies or culturing the producer cell lines in the presence of anti-retroviral drugs to interfere with the production of infectious virions.  Collectively, our results show how viruses use EV pathways to release their cargo prior to virion release and the virions are very heterogenous in size, biochemical and biophysical characteristics.