Contributions of E1A to mouse adenovirus type 1 pathogenesis following intranasal inoculation.

We investigated the role of mouse adenovirus type 1 (MAV-1) early region 1A (E1A) protein in adenovirus respiratory infection. Intranasal (i.n.) inoculation of mice with wild type (wt) virus induced chemokine and cellular inflammatory responses in the lung. We observed similar responses in mice infected with an E1A-null mutant virus at the same dose, although the magnitude of these responses was lower. Levels of viral hexon gene expression were lower in the lung following infection with E1A-null virus than with wt virus. When input doses were adjusted so that equivalent viral loads were present following infection with varying doses of wt and E1A-null virus, we observed equivalent chemokine upregulation in the lung. Dissemination to the brain occurred following i.n. inoculation with equal doses of wt or E1A-null virus, but viral gene expression and viral loads were lower and the magnitude of chemokine responses was lower in brains of E1A-null virus-infected mice. CD4 and CD8 T cells and neutrophils were recruited to the brains of mice infected with either wt or E1A-null virus. Together, these data suggest that MAV-1 E1A makes important contributions to viral replication in the lung and the brain following i.n. inoculation. However, E1A is not essential for the induction of inflammatory responses in the lung or for viral dissemination out of the lung.

Acute respiratory infection with mouse adenovirus type 1.

Studies of the pathogenesis of adenovirus respiratory disease are limited by the strict species-specificity of the adenoviruses. Following intranasal inoculation of adult C57BL/6 mice with mouse adenovirus type 1 (MAV-1), we detected MAV-1 early region 3 (E3) and hexon gene expression in the lungs at 7 days post-infection (dpi). We detected MAV-1 E3 protein in the respiratory epithelium at 7 dpi. We did not detect viral mRNA or protein at 14 dpi, but MAV-1 DNA was detected by PCR at 21 dpi. Chemokine transcript levels increased between 7 and 14 dpi in the lungs of infected mice. MAV-1 infection induced a patchy cellular infiltrate in lungs at 7 and 14 dpi. This is the first report demonstrating the presence of MAV-1 in the respiratory epithelium of infected mice and describing chemokine responses in the lung induced by MAV-1 respiratory infection. MAV-1 infection of mice has the potential to serve as a model for inflammatory changes seen in human adenovirus respiratory disease.