Activation of Latent Mouse Pneumonitis Virus by Human Serum. ∗

Summary and Conclusions.

The intranasal inoculation of fresh human serum in mice resulted in the development of pulmonary consolidation in a high percentage of animals. Structures resembling elementary bodies were seen in impression films prepared from these lesions. Serial passage in mice yielded irregular results, although in 2 series consolidation recurred in each of 3 passages. Serial passage on the chorioallantoic membrane of chick embryos resulted in the isolation of 2 strains of a pneumotropic elementary body virus. Cross complement fixation tests demonstrated that this virus was related antigenically to other members of the psittacosis-lymphogranuloma group of viruses. These observations suggest the possibility that this virus may be present in latent from in a considerable number of laboratory mice. The finding that the virus can be activated by the intranasal inoculation of fresh human serum seems of considerable interest.