Highlights d Acute SARS-CoV-2 infection is associated with shifts in the nasal microbiome d Abundance of Pseudomonas aeruginosa increases with SARS-CoV-2 viral RNA load d Healthcare providers and infected patients share some nasal microbiome features d The nasal transcriptome of infected patients reveals inflammation and neuron damage

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Much of the research conducted on SARS-CoV-2 and COVID-19 has focused on the systemic host response, especially that generated by severely ill patients. Very few studies have investigated the impact of acute SARS-CoV-2 within the nasopharynx, the site of initial infection and viral replication. In this study we profiled changes in the nasal microbial communities as well as in host transcriptional profile during acute SARS-CoV-2 infection using 16S amplicon sequencing and RNA sequencing. These analyses were coupled to viral genome sequencing. Our microbiome analysis revealed that the nasal microbiome of COVID patients was unique and was marked by an expansion of bacterial pathogens. Some of these microbes (i.e. Acinetobacter) were shared with COVID negative health care providers from the same medical center but absent in COVID negative outpatients seeking care at the same institutions suggesting acquisition of nosocomial respiratory pathogens. Specifically, we report a distinct increase in the prevalence and abundance of the pathogen Pseudomonas aeruginosa in COVID patients that correlated with viral RNA load. These data suggest that the inflammatory environment caused by SARS-CoV-2 infection and potentially exposure to the hospital environment leads to an expansion of bacterial pathogens in the nasal cavity that could contribute to increased incidence of secondary bacterial infections. Additionally, we observed a robust host transcriptional response in the nasal epithelia of COVID patients, indicative of an antiviral innate immune repones and neuronal damage. Finally, analysis of viral genomes did not reveal an association between viral loads and viral sequences.

Pregnancy and the postpartum period result in some of the most dramatic metabolic, hormonal, and physiological changes that can be experienced by an otherwise healthy adult. The timing and magnitude of these changes is key for both maternal and fetal health. One of the factors believed to critically modulate these physiological changes is the maternal gut microbiome. However, the dynamic changes in this community during the perinatal period remain understudied. Clinical studies can be complicated by confounding variables such as diet and other drivers of heterogeneity in the human microbiome. Therefore, in this study, we conducted a longitudinal analysis of the fecal microbiome obtained during the perinatal and post-partum periods in 25 rhesus macaques using 16S rRNA gene amplicon sequencing and shotgun metagenomics. Shifts at both the taxonomic and functional potential level were detected when comparing pregnancy to postpartum samples. Taxonomically, Alloprevotella, Actinobacillus, and Anaerovibrio were enriched during pregnancy while Treponema, Lachnospiraceae, and Methanosphaera were more abundant post-partum. Functionally, pregnancy was associated with increased abundance in the pathway to produce the beneficial short chain fatty acid (SCFA), butyrate, while pathways associated with starch degradation and folate transformation were more abundant postpartum. These data demonstrate dramatic changes in the maternal gut even in the absence of dietary changes and suggest that rhesus macaques could provide a valuable model to determine how changes in the microbiome correlate to other physiological changes in pregnancy.

Pregnancy and the postpartum period are characterized by a myriad of metabolic and physiological adaptations needed to support fetal growth and maternal health. The maternal gut microbiome is believed to play a key role during this period but remains underexplored.