Wounding: The primary mode of Seoul virus transmission among male Norway rats

In rodent populations, males are more likely to be infected with hantaviruses and to engage in aggression than are females. To assess the relationship between aggression and Seoul virus infection, Norway rats were trapped in Baltimore, Maryland and wounding, infection status, and steroid hormone concentrations were examined. Older males and males with high-grade wounds were more likely to have IgG antibody to Seoul, to shed virus in saliva, urine, and feces, and to have viral RNA in organs than either juveniles or adult males with less severe wounds. In contrast, neither age nor wounding predicted virus shedding among females. Although viral antigen was not identified in the brain, viral protein was detected in the gonads and adrenal glands of adult males. Males with more severe wounds had higher testosterone concentrations than males with no or low-grade wounds. Because wounding, testosterone, and virus shedding are associated among males, aggression may be the primary mode of Seoul virus transmission among male, but not female, Norway rats.