The clinical outcome of COVID-19 is strongly associated with microbiome dynamics in the upper respiratory tract

The "crossover effect" of COVID-19 in pregnancy on the infant microbiome

Background

The COVID-19 pandemic has had a significant impact on public health. However, the impact of COVID-19 infection during pregnancy on the microbiome of the mother and her newborn child still remains poorly understood.

Methods

This study involved 94 mother-child pairs whose mothers had COVID-19 during pregnancy and 44 newborns as a control group recruited in 2018. Stool samples were collected from women before delivery and from infants at 5-7 days after birth and used for 16S rRNA sequencing.

Results

We found that the microbiomes of infants exposed in utero to COVID-19 showed decreased microbial diversity and richness. Moreover, we observed a higher inter-sample variability between infant samples in the case group, which might suggest destabilization of their microbiomes. Neither alpha- nor beta-diversity metrics differed significantly between the groups depending on the trimester when the mother contracted COVID-19. Thus, the timing of prenatal COVID-19 exposure had no effect on the infant gut microbiome.

Conclusion

COVID-19 during pregnancy can significantly compromise the establishment of the infant gut microbiome presumably by disrupting the mother's microbiome.

Individual virome analysis reveals the general co-infection of mammal-associated viruses with SARS-related coronaviruses in bats

Bats are the natural reservoir hosts for SARS-related coronavirus (SARSr-CoV) and other highly pathogenic microorganisms. Therefore, it is conceivable that an individual bat may harbor multiple microbes. However, there is limited knowledge on the overall co-circulation of microorganisms in bats. Here, we conducted a 16-year monitoring of bat viruses in south and central China and identified 238 SARSr-CoV positive samples across nine bat species from ten provinces or administrative districts. Among these, 76 individual samples were selected for further metagenomics analysis. We found a complex microenvironment characterized by the general co-circulation of microbes from two different sources: mammal-associated viruses or environment-associated microbes. The later includes commensal bacteria, enterobacteria-related phages, and insect or fungal viruses of food origin. Results showed that 25% (19/76) of the samples contained at least one another mammal-associated virus, notably alphacoronaviruses (13/76) such as AlphaCoV/YN2012, HKU2-related CoV and AlphaCoV/Rf-HuB2013, along with viruses from other families. Notably, we observed three viruses co-circulating within a single bat, comprising two coronavirus species and one picornavirus. Our analysis also revealed the potential presence of pathogenic bacteria or fungi in bats. Furthermore, we obtained 25 viral genomes from the 76 bat SARSr-CoV positive samples, some of which formed new evolutionary lineages. Collectively, our study reveals the complex microenvironment of bat microbiome, facilitating deeper investigations into their pathogenic potential and the likelihood of cross-species transmission.