Sequence analysis and acute pathogenicity of molecularly cloned SIVSMM-PBj14.

The PBj14 isolate of simian immunodeficiency virus from sooty mangabey monkeys (SIVSMM-PBj14) is the most acutely pathogenic primate lentivirus so far described, always causing fatal disease in pig-tailed macaques (Macaca nemestrina) within 8 days of inoculation. As a first step in identifying viral genes and gene products that influence pathogenicity, the SIVSMM-PBj14 genome was amplified by the polymerase chain reaction as 5' and 3' genomic halves of 5.1 and 5.8 kilobases, respectively, and molecularly cloned. DNA sequence analysis revealed a high degree of conservation with other SIVs, except for a 22-base-pair duplication in the enhancer region of the viral long terminal repeat which included a second binding site for the transcription factor NF-kappa B. Of six genomic halves examined, four contributed to the formation of infectious virus that induced acute disease and death in pig-tailed macaques as early as 6 days post-inoculation, with pathology, disease syndromes and kinetics indistinguishable from those induced by the uncloned isolate. To our knowledge this is the first example of acute immunodeficiency disease induced by a molecularly defined lentivirus. Furthermore, the molecularly cloned SIVSMM-PBj14 viruses share with the uncloned virus cytopathicity for mangabey CD4+ cells, a property that may correlate with their observed pathogenicity in vivo.