Using human intestinal organoids to evaluate JCV fecal/oral transmission

Project summary JC virus (JCV) is a human polyomavirus which infects most of the human population worldwide during early childhood with 50-70% of the adult population being seropositive for the virus. JCV is thought to be transmitted by the oral/fecal route however the primary site of infection has not been identified. Following an initial infection, JCV transits into the kidneys where it establishes a lifelong infection. For most people this infection is latent and no new virus particles are detected, however about 8-20% of people have a low-level virus production leading to the excretion of virus into the urine. For immune-competent individuals these lifelong infections will be asymptomatic. However, for immune-suppressed patients, these viruses can reactivate leading to fatal disorders. Upon immunosuppression, JCV will leave the kidney and move to the brain where it will infect the myelin-producing oligodendrocytes. Infection of the oligodendrocytes will lead to their lytic destruction causing the fatal disorder Progressive Multifocal Leukoencephalopathy (PML). JCV genomes have been found in both upper and lower gastrointestinal tissues and in feces suggesting that human intestinal cells can support JCV infection. While the consensus view is that initial infection of the human population by JCV is by ingestion, direct evidence of infection of the intestine is lacking. Most importantly, how JCV passes the intestinal epithelial cell barrier en route to the kidney remains unknown. We plan to fill these gaps in knowledge and study how JCV infects, replicates, and spreads in human intestinal epithelial cells. Understanding the enteric phase of JCV is of major significance to understand JCV pathogenesis as it is believed to constitute the entry site from which 70% of the population becomes infected. In a set of preliminary data using human intestinal organoids, as a surrogate system to study JCV infection in human primary intestinal cells, we could show that JCV can replicate in human intestinal cells and produce de novo infectious virus particles. In this proposal, we will build on our preliminary data and address the cellular tropism of JCV by evaluating the susceptibility of different human intestinal cell types to JCV infection. Additionally, we will test whether all sections of the gastrointestinal tract (duodenum, jejunum, ileum, and colon) can support JCV infection. Finally, we will determine how JCV passes the intestinal epithelial barrier en route to the kidney to establish its chronic infection. We anticipate that this work will provide us with unique opportunities to identify novel therapeutic to prevent infection/transmission from the intestinal mucosa. Importantly this work, will constitute the building block for future research that will integrate the natural gut/kidney axis that is likely to play an important role in JCV infection and pathogenesis.