Vincent, H. A. | bioRxiv Science

bioRxiv2021

The membrane associated accessory protein is an adeno-associated viral egress factor

Adeno-associated viruses (AAV) rely on helper viruses to transition from latency to lytic infection. Some recombinant AAV serotypes are secreted in a pre-lytic manner as extracellular vesicle (EV)-associated particles, although mechanisms underlying such are unknown. Here, we discover that the membrane-associated accessory protein (MAAP), expressed from a (+1) frameshifted open reading frame (ORF) in the AAV capsid (cap) gene, is a novel viral egress factor. MAAP contains a highly conserved, cationic amphipathic domain critical for AAV secretion. Wild type or recombinant AAV with a mutated MAAP start site (MAAP{Delta}) show markedly attenuated secretion and correspondingly, increased intracellular retention. Trans-complementation with recombinant MAAP restored extracellular secretion of multiple AAV/MAAP{Delta} serotypes. MAAP is sorted into recycling Rab11+ vesicles and strongly associates with EV markers upon fractionation. In addition to characterizing a novel viral egress factor, these studies highlight a prospective engineering platform to modulate secretion of AAV vectors or other EV-associated cargo.

molecular biology↗

bioRxiv2020

Comparative analysis of coronavirus genomic RNA structure reveals conservation in SARS-like coronaviruses

Coronaviruses, including SARS-CoV-2 the etiological agent of COVID-19 disease, have caused multiple epidemic and pandemic outbreaks in the past 20 years1-3. With no vaccines, and only recently developed antiviral therapeutics, we are ill equipped to handle coronavirus outbreaks4. A better understanding of the molecular mechanisms that regulate coronavirus replication and pathogenesis is needed to guide the development of new antiviral therapeutics and vaccines. RNA secondary structures play critical roles in multiple aspects of coronavirus replication, but the extent and conservation of RNA secondary structure across coronavirus genomes is unknown5. Here, we define highly structured RNA regions throughout the MERS-CoV, SARS-CoV, and SARS-CoV-2 genomes. We find that highly stable RNA structures are pervasive throughout coronavirus genomes, and are conserved between the SARS-like CoV. Our data suggests that selective pressure helps preserve RNA secondary structure in coronavirus genomes, suggesting that these structures may play important roles in virus replication and pathogenesis. Thus, disruption of conserved RNA secondary structures could be a novel strategy for the generation of attenuated SARS-CoV-2 vaccines for use against the current COVID-19 pandemic.

microbiology↗