SARS-CoV-2 Interference of Influenza Virus Replication in Syrian Hamsters

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Background

Simultaneous infections or co-infections with more than one respiratory virus is not uncommon in humans, particularly in hospital settings. Myxovirus resistance (Mx) proteins have antiviral activity against multiple RNA viruses, including influenza viruses. Because SARS coronavirus 2 (SARS-CoV-2) induces strong, diffuse expression of Mx protein 1 (Mx1) in the lungs of infected hamsters, we decided to examine the interference of influenza virus replication in Syrian golden hamsters coinfected or previously infected with SARS-CoV-2.

Methods

Four-to-five-week-old female Syrian golden hamsters were inoculated with SARS-CoV-2, H3N2 influenza virus, or a mixture of both viruses. All animals were infected via intranasal inoculation, with the same concentration of virus and at the same total inoculum volume (130 µL). Animals in the control groups were inoculated with 130 µL of sterile phosphate-buffered saline.

Results

In hamsters, SARS-CoV-2 infection at the same time as, or before H3N2 influenza virus, infection resulted in significantly reduced influenza virus titers in the lungs and nasal turbinates. This interference may be correlated with SARS-CoV-2-induced expression of MX1.

Conclusions

Syrian golden hamsters are an ideal animal model to examine the consequences of simultaneous and serial infection of SARS-CoV-2 and influenza virus, as well as the host factors (e.g., antiviral genes like MX1) that are induced by one virus to suppress the other virus. Although our data suggest that the induction of MX1 by SARS-CoV-2 restricts influenza virus infection, the induction of MX1 by influenza virus had no effect on SARS-CoV-2 replication, an observation of potential antagonism of MX1 function by SARS-CoV-2 that should be further studied.

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The full text of this study can be accessed via the source information below.