Construction and validation of a mouse model for studying severe human adenovirus infections.

Human adenoviruses (HAdVs) are highly contagious pathogens with various genotypes implicated in acute respiratory disease (ARD) and linked to mortality, especially in immunosuppressed patients, young children, and military recruits. Currently, no vaccines or specific drugs are approved for clinical use. The hosts of adenoviruses are strictly species-specific, which strongly limits the development of vaccines and drugs against HAdVs. In this study, immunocompetent BALB/c mice were challenged with different doses of human adenovirus type 5 (HAdV-5) via tail intravenous injection (i.v.). All mice challenged with a high dose of HAdV-5 (3.2×10¹⁰ TCID₅₀/kg) died within 3 to 5 days, while those receiving a low dose of HAdV-5 (8×10⁹ or 4×10⁹ TCID₅₀/kg) survived. Interestingly, among the mice receiving a medium dose of HAdV-5 (1.6×10¹⁰ TCID₅₀/kg), 60% (n = 3/5) of male mice died, while all female mice survived. This suggests that male mice may be more susceptible to HAdV-5 infection than female mice, consistent with clinical findings in children. HAdV-5 DNA was mainly distributed in the liver, followed by the spleen and lungs. Pathological changes were observed in the lungs, liver, and spleen, with severity increasing in correlation with the virus challenge dosage. Transcriptome and qPCR analyses of the liver indicated that the down-regulated expression of the H2-Aa, H2-Ea-ps, CD74, and H2-Eb1 genes in male mice, as well as the AHR gene in female mice, may contribute to the observed higher mortality rates in male mice. Therefore, this effective, feasible, and cost-efficient mouse model could serve as a candidate for evaluating HAdV vaccines and anti-adenovirus therapeutics.