Role of hemopoietic colony-forming cell responses in the pathogenesis of ectromelia.

Intraperitoneal injection of complete Freund's adjuvant which caused an extensive cellular response in the reticuloendothelial system greatly increased the severity of infection which resulted from footpad inoculation of ectromelia virus in mice. The mortality was greatest during the proliferative phase of the cellular response, indicated by the colony-forming cell response. Exposure of colony-forming cells to virus in vitro showed that those from normal bone marrow were much less susceptible to virus than those from the bone marrow of adjuvant-treated mice and more particularly those from the spleen of adjuvant-treated mice. Severe bleeding to induce anemia and a consequent erythropoietic response did not increase the mortality from ectromelia. Previous results were interpreted on the basis of these findings and a more general application of them to the pathogenesis of poxvirus infection was discussed.