Shuchun Zhang | PubMed Health

PubMed2026

SARS-CoV-2 3CLpro inhibits the replication of influenza viruses through the cleavage of NP and PA.

The co-circulation of multiple viruses can lead to distinct pathological outcomes, yet how severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection influences other viral infections remains poorly understood, despite its documented high frequency during the pandemic. In this study, we investigated how the proteolytic activity of SARS-CoV-2 3C-like protease (3CLpro) influences the replication of influenza A virus. In silico analysis identified candidate 3CLpro cleavage sites across numerous viral proteins, and biochemical assays confirmed that 3CLpro catalyzes the degradation of influenza virus nucleoprotein (NP) and polymerase acidic protein (PA) in a manner requiring its protease activity. This degradation of NP and PA, which are essential for viral genome packaging and transcription, disrupted the influenza replicative cycle and suppressed viral replication, both upon ectopic 3CLpro expression and during SARS-CoV-2 infection. Our data uncover a direct, enzyme-based mechanism by which SARS-CoV-2 can suppress influenza virus replication during coinfection. We provide a molecular explanation for the sharp, global decline in influenza activity observed during the COVID-19 pandemic and illustrate how enzymatic weapons of one virus can be repurposed to restrain a competing pathogen.

Virus Replication↗

PubMed2002

[The dose-response relationship study between the quantitative morphological stereology on thyroid and different iodine doses in mice].

OBJECTIVE: To study the dose-response relationship between the quantitative morphological stereology on thyroid and different iodine doses in mice. METHODS: Weaning Kunming mice were randomly divided into seven groups. The mice were fed for 100 days with distilled water containing different KIO3 concentrations, i.e. 50, 250, 500, 1 000, 1 500, 2 000, and 3 000 microgram/L respectively. The 50 microgram/L (proper iodine concentration) group was control group, and the groups of 250 approximately 3 000 microgram/L were high iodine groups. The stereology parameters of thyroid follicle and follicular cavities were measured with HPIAS-1000 (High Resolution Pathological Image & word Analysis System). The stereology parameters included mean surface, volume on area, volume on circumference, specific surface, numerical density on area, spherical factor, the percentage of mean surface and mean volume of the follicular epithelial cell in thyroid follicle was further calculated. RESULTS: Positive correlations was observed between the thyroid absolute and relative weight, goiter rate and different iodine doses. And the thyroid absolute and relative weight of mice in the 250 microgram/L group was significantly different from that in 50 microgram/L group. The goiter rate of mice in different high iodine groups was in conformity with that of epidemiological investigation. The goiter rate of mice in 500 microgram/L group was different from that in 50 microgram/L group. Positive correlations were observed between mean surface, volume on area, volume on circumference, spherical factor and iodine doses, but the negative correlations were observed between numerical density on area, specific surface, the percentage of mean surface and mean volume of the follicular epithelial cell in thyroid follicle and iodine doses. CONCLUSIONS: When Iodine doses are between 250 approximately 3 000 microgram/L, the dose-response relationship was observed between the morphological stereology parameters of thyroid follicle and follicular cavities and iodine doses, and when the dose of iodine is 250 microgram/L, it is possible to induce colloid goiter of mice. The goiter rates of mice resulted by different high iodine doses were in conformity with that of the epidemiological investigation of people.

Animals↗