Both systemic and mucosal LCMV immunization generate robust viral-specific IgG in mucosal secretions, but elicit poor LCMV-specific IgA.

Immunoglobulins in secretions play a critical role in protection at mucosal surfaces. We examined the generation of viral-specific IgG and IgA in plasma and mucosal secretions of mice following systemic or mucosal immunization with lymphocytic choriomeningitis virus (LCMV), a widely used experimental model of viral infection. While there are early differences in humoral responses depending on the route of viral entry, we show that both routes generate comparably robust viral-specific IgG in plasma, vaginal, lung, and nasal secretions of immune mice. In contrast, LCMV elicited poor viral-specific IgA responses. Mice that were infected IN showed elevated viral-specific IgA in nasal and lung washes compared to IP-infected mice; however, LCMV-specific IgG overwhelmingly contributed to the humoral response in all mucosal secretions examined. Thus similarly to HIV-1, and several other mucosally-encountered microbial infections, these data suggest that LCMV infection fails to induce vigorous viral-specific IgA responses.