PROJECT SUMMARY
Human norovirus (HuNoV) is the leading cause of acute gastroenteritis in the United States, resulting in $4.2
billion in direct health system costs annually. Due to underlying immunosuppression and the lack of effective
antiviral therapeutics, transplant patients may develop serious sequelae from HuNoV infections. Though
bacterial gut microbiota has been shown to enhance replication and pathogenesis of enteric viruses in preclinical
models, its role in HuNoV infection remains largely unknown. In this project, we aim to gain greater mechanistic
insights into how gut microbiota modulate HuNoV infection in transplant patients. Our central hypothesis is that
transplant patients with symptomatic HuNoV infection will have a gut microbiome signature showing an
enrichment of specific gut microbiota (Enterobacteriaceae) that facilitate infection of HIEs, and those who
develop chronic symptoms from HuNoV infection will have a concomitant depletion of specific gut microbiota
that modulate host innate immune responses (type 1 interferons). In Aim 1, we will further define both gut
microbiome and host factor differences in transplant patients ±HuNoV infections. First, we will establish a larger
cohort of adult and pediatric transplant patients and collect longitudinal stool specimens. Then, we will perform
comprehensive gut microbiome profiling (metagenomic shotgun sequencing and bacterial qPCR) to confirm our
preliminary results. We predict that HuNoV-infected transplant patients will have significantly different gut
microbiota signatures compared to uninfected counterparts, and that higher intensity of immunosuppression and
high antibiotic load will correspond with chronic diarrhea in HuNoV-infected transplant patients. In Aim 2, we will
determine if Enterobacteriaceae facilitate HuNoV infection using an in vitro HIE model. First, we will infect jejunal
HIEs with HuNoV and co-incubate HuNoV with various Enterobacteriaceae spp. Then, we will perform RNA
extractions and quantitative HuNoV RT-qPCR to evaluate the effect of co-incubating various Enterobacteriaceae
spp. on viral replication. We predict that Enterobacteriaceae promotes HuNoV infection of HIEs. If this is the
case, we will investigate if this is a phenomenon observed only in HBGA-expressing members of
Enterobacteriaceae. In Aim 3, we will determine if transplant patients with chronic symptomatic HuNoV infections
have different systemic cytokine signatures compared to uninfected counterparts. We will perform bulk cytokine
analysis on serum samples utilizing Isoplexis, a novel functional proteomic profiling platform. We predict that
transplant patients with chronic diarrhea from HuNoV infection will exhibit a paucity of genus Bacteroides,
resulting in depletion of type 1 interferons, which then leads to a decreased Th1 immune response, increased
Th2 immune response and increased expression of Th2-predominant cytokines (IL-4, IL-5, IL-10). The proposed
experiments, training and didactic coursework in this K23 will equip the candidate (Dr. Chong) with unique
skillsets that will enable her transition to independence as a physician scientist in gut microbiota-HuNoV
interactions in transplant patients.