Respiratory infectivity of a recently isolated Egyptian strain of Rift Valley fever virus.
The respiratory infectivity of a strain of Rift Valley fever virus isolated in Egypt (strain ZH-501) was compared with that of one isolate from Uganda (Entebbe strain) and two isolates from South Africa (strains SA-51 and SA-75). Studies were performed with ICR mice which were infected by exposure to infectious aerosols composed of particles with a mass median diameter of 0.96 micrometer. The respiratory median lethal doses for ZH-501, Entebbe, SA-51, and SA-75 were 2.2, 1.9, 2.6, and 1.9 log10 plaque-forming units, respectively. Although these values are statistically different, the biological implications of such differences seem unimportant. In an additional study of pathogenesis, a single group of mice was infected with 3.1 log10 plaque-forming units of ZH-501, and tissues were assayed sequentially through 96 h postinfection. Between 6 and 30 h, demonstration of an increasing virus concentration only in the lungs indicated that initial replication occurred there; however, determination of histopathological changes did not reveal evidence of pneumonia. Virus was isolated from the liver by 48 h, and the ultimate outcome of infection was a fulminating and fatal hepatic necrosis.
D000336:Aerosols; D000818:Animals; D002043:Bunyaviridae / Q000472:pathogenicity*; D004534:Egypt; D007928:Lethal Dose 50; D008099:Liver / Q000473:pathology; D008168:Lung / Q000473:pathology; D051379:Mice; D012141:Respiratory Tract Infections / Q000382:microbiology*; D012295:Rift Valley Fever / Q000382:microbiology* / Q000473:pathology / Q000635:transmission; D012296:Rift Valley fever virus / Q000254:growth & development / Q000472:pathogenicity*
D000336:Aerosols