Characterization and distribution of two new foamy viruses isolated from chimpanzees

Abstract

Pan 1 and Pan 2 viruses are persistent viruses recoverable from many organs, including brain, of most chimpanzees; both may be present in the same organ of a given animal. These viruses induce a vacuolated, foamy syncytia without inclusion bodies both in chimpanzee explant cultures and in primary human embryo kidney (HEK) cells. Both viruses are not inhibited by IUDR. are chloroform and pH 3.0 sensitive and are inactivated following exposure to 45° C for 30 minutes. Pan 2 virus, the only one tested, is sensitive to visible light. Neither virus has yielded a detectable hemagglutinin, nor has hemadsorption of guinea pig RBC been observed. Direct and blind passage inoculations have not induced infection or evidence of viral replication in small laboratory animals. By electron microscopy they are indistinguishable from each other and are approximately 125 nm in diamter. Viral antigens are demonstrable in in vitro cultures of chimpanzee tissues as well as infected HEK cells by direct fluorescent antibody staining. Pan 1 and Pan 2 viruses do not share common antigens detectable by neutralization or fluorescent antibody staining. The viruses are not neutralized by reference reagent antisera specific for simian foamy virus types 1, 3, 4, 5, measles, canine distemper or other myxo- and pseudomyxoviruses tested. Antiserum prepared against foamy virus type 2, at a dilution of 1:10, neutralizes 50 TCID50 of Pan 2 virus, whereas antiserum prepared against Pan 2 virus does not neutralize foamy virus, type 2. Homologous antibody is present in the serum of each chimpanzee from whose tissue the virus has been recovered. Antibodies to the Pan foamy viruses have been detected in uninoculated control chimpanzees and in those bled in the African bush. © 1972 Springer-Verlag.