Susceptibility of Kangaroo Rats to Strains of Human Influenza Virus.

Abstract

The difficulty of isolating certain strains of influenza virus, especially influenza B, by ferret inoculation has led to a search for more susceptible animals. This paper will report the results of preliminary experiments with 2 species of kangaroo rat (Dipodomys deserti deserti and Dipodomys merriami simiolus) which were trapped in Southern California and Arizona. Most of the results to be reported were obtained with Dipodomys merriami simiolus which appeared to be slightly more susceptible than the other species. Results with Influenza A Virus. Eight kangaroo rats were inoculated intranasally under ether anesthesia with 10% lung suspension-of the 352nd mouse passage of the strain PR8. Two died in 3 and 4 days respectively with massive consolidation of the lungs, 2 survived with consolidation of a considerable part of the lungs, and 4 showed no definite macroscopic lung lesions. Kangaroo rats inoculated with material from the consolidated lungs of the first passage developed only small lung lesions. Virus was demonstrated in the normal appearing lungs of 2 animals by subinoculation of mice and neutralizing antibodies for the strain PR8 were found in the serum of recovered animals. Of 4 kangaroo rats inoculated with the 97th direct ferret passage of strain PR8 none showed definite lung lesions. Two human throat washings demonstrated to contain the virus of influenza A by inoculation of ferrets were instilled into the noses of kangaroo rats and passage of material from the lungs and turbinates was carried out at intervals of 4 to 5 days. Neither lung lesions nor neutralizing antibodies to PR8 were demonstrated in any of the animals. The results indicate that mouse passage strains of influenza A are more virulent for Dipodomys than are strains from ferrets or human beings.