MATERNAL ANTIBODIES PROTECT IMMUNOGLOBULIN DEFICIENT NEONATAL MICE FROM MOUSE HEPATITIS-VIRUS (MHV)-ASSOCIATED WASTING SYNDROME

PROBLEM: Neonatal mice nursed by dams lacking immunoglobulins (Igs) ma y often suffer from lethal runting if raised under conventional condit ions. The present study was per formed in order to clarify a) the caus e of the wasting syndrome and b) the protective role of antigen-specif ic milk antibodies. METHOD: Ig-deficient mouse embryos in a convention al environment were embryo-transferred to specified pathogen free (SPF ) dams. Neonatal growth, mortality, and health status of mice from bot h environments was recorded. Suspected presence of mouse hepatitis vir us (MHV) was tested by RT-PCR. Protective effects on neonatal mortalit y of milk containing different titers of anti-MHV antibodies were inve stigated in cross-fostering experiments. RESULTS: The SPF colony of Ig -deficient mice exhibited no breeding problems, whereas Ig-deficient n eonates in the conventional environment suffered from lethal wasting s yndrome. Serological screening of the mice kept in the two environment s revealed that mice in the conventional room had high titers of antib odies against mouse hepatitis virus. Presence of MHV in runting neonat es was confirmed by pathological examinations and RT-nested-PCR using MHV genome specific primers. Milk containing high titers of anti-MHV a ntibodies, when provided for 8 days or more, completely prevented Ig-d eficient neonates from developing wasting syndrome in the conventional environment. CONCLUSION: These findings show that the neonatal wastin g syndrome is associated with the presence of MHV and that neonates ar e efficiently protected by MHV-specific antibodies in the milk.