ABSTRACT
Secondary bacterial infections can exacerbate SARS-CoV-2 infection, but their prevalence and impact remain poorly understood. Here, we established that a mild to moderate SARS-CoV-2 infection increased the risk of pneumococcal coinfection in a time-dependent, but sexindependent, manner in the transgenic K18-hACE mouse model of COVID-19. Bacterial coinfection was not established at 3 d post-virus, but increased lethality was observed when the bacteria was initiated at 5 or 7 d post-virus infection (pvi). Bacterial outgrowth was accompanied by neutrophilia in the groups coinfected at 7 d pvi and reductions in B cells, T cells, IL-6, IL-15, IL-18, and LIF were present in groups coinfected at 5 d pvi. However, viral burden, lung pathology, cytokines, chemokines, and immune cell activation were largely unchanged after bacterial coinfection. Examining surviving animals more than a week after infection resolution suggested that immune cell activation remained high and was exacerbated in the lungs of coinfected animals compared with SARS-CoV-2 infection alone. These data suggest that SARS-CoV-2 increases susceptibility and pathogenicity to bacterial coinfection, and further studies are needed to understand and combat disease associated with bacterial pneumonia in COVID-19 patients.
ABSTRACT
The emergent global pandemic caused by the rapid spread of Severe Acute Respiratory syndrome-Coronavirus-2 (SARS-CoV-2) has led to increased mortality and negatively impacted day to day activities of humankind within a short period of time. As the data is rapidly emerging from earlier outbreak locations around the world, there are efforts to assimilate this with the knowledge from prior epidemics and find rapid solutions for this. One of the observations and a recurring theme is the disproportionate differences in the incidence of infection and the consequent mortality between males and females. We, therefore, analyzed retrospective datasets from the previous epidemics and the ongoing pandemic in order to address these differences in clinical outcomes. The data shows that even though the infection rates are similar, the odds ratio of male mortality remains high, indicating a divergence in the crosstalk between the three pathogenic human Coronavirus (hCoVs)-the SARS-CoV, MERS-CoV and the SARS-CoV-2 and immune effectors in the two sexes. One proximate cause is the sex-specific modulation of the X-linked genes that can influence susceptibility to infection. Future studies are needed to confirm these findings, which can form the basis for developing rational strategies for ending the current and preventing future pandemics.
