Enteroviruses are among the most severe causes of human disease, and recent outbreaks of emerging

enteroviruses such as types D68 and 71 have highlighted the need to understand more about these

pathogens. Our comparative studies of poliovirus (PV), coxsackievirus B3, and now EV-D68 have shown many commonalities in the life-cycles of these viruses. We have focused our studies on how members of the Enterovirus genus trigger a cellular pathway known as autophagy to promote production of infectious virus.

 

Autophagy is a constitutive degradative cellular process required for turnover of damaged vesicles, aggregated proteins, and other spent cellular components. During times of stress, including amino acid starvation, organismal development, and infection, autophagy is up-regulated. Autophagic vesicles, thought to be derived from the complex web of viral RNA replication membranes, can be observed during mid-to-late infection.

 

We and others have demonstrated that viral proteins specifically induce autophagic signaling and autophagosome formation. These autophagosomes acidify, promoting maturation of the viral capsid and release of newly formed infectious viruses, often encased in these cell-derived membranes, from the cell. 

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Our lab is dedicated to understanding the generation and regulation of membranes during infection, from the initial RNA replication membranes to the autophagosomes promoting maturation of virions to the single-membraned virus-containing vesicles being released from the cell. Understanding this entire pathway, the latter parts of which have only been identified within the past few years, will provide an understanding of how these viruses replicate, mature, release from cells, and evade immune detection.

 

Some of our projects include:

 

• How specific viral non-structural proteins initiate autophagosome formation at the early stages of infection and regulate downstream steps in autophagosome formation, acidic maturation, and virus release. 

• The viral and host requirements for development of viral RNA replication membranes, and the mechanism of formation of autophagosomes from these convoluted membrane structures during infection.

• Regulation of autophagy through novel localization of viral and autophagic proteins.

• How acidic autophagosomes form and promote maturation of the virion by inducing cleavage of the capsid protein VP0 into VP2 and VP4. 

• The multiple roles of the SNARE proteins in regulation virus entry, replication, maturation, and release, including SNAP29, part of a complex that mediates fusion between acidic autophagosomes and lysosomes. SNAP29 is cleaved by the viral 3C protease late in infection, but is required early.  

• The role of another SNARE in the same family, SNAP47, which associates with the endosomal SNARE VAMP7, and is required for normal autophagy and EV-D68 replication. 

• The roles of another SNARE, SNAP23 in redirecting membranes to fuse with the plasma membrane and are released from cells.

• The role and regulation of the neuron-specific SNARE SNAP25 during infection of neuronal cells.

• The role of SARS-CoV-2 proteins in inducing and regulating autophagy.