The immune response of the mouse to lymphocytic choriomeningitis virus. I. Circulating antibodies.

A search was made in LCM virus-immune mice for virus-specific antibodies. With the help of an L-cell plaque assay, neutralizing antibody was readily detected. There were no essential differences between mouse strains, but marked differences existed between virus strains. Whereas the inoculation of either large or small doses of WE strain virus led to the early production of considerable concentrations of neutralizing antibody, in the case of E-350 strain virus, high doses were required and a much longer time interval had to elapse before the threshold of detection was attained. In addition to neutralizing antibody, LCM virus-infected mice produced sensitizing antibody (detected by the enhancing effect of an anti-mouse Ig antiserum on the ability of a serum to reduce virus infectivity) and complement-fixing antibody. Previous failures to detect neutralizing antibody in LCM virus-immune mice might have been caused by properties of the chosen virus, but in many instances lack of a suitable assay host is a more likely explanation.