A putative DNA helicase and novel oligoribonuclease in the Diachasmimorpha longicaudata entomopoxvirus (DlEPV).

Diachasmimorpha longicaudata entomopoxvirus (DlEPV) is a symbiotic entomopoxvirus (EPV) of the parasitic wasp Diachasmimorpha longicaudata. It has a double-stranded DNA genome of 250-300 kb and is >60% A-T rich. We describe ten ORFs (RI-35-1 to -10) contained within a 5.64 kb clone, RI-35, from a DlEPV EcoRI genomic library. Our goal was to identify unique motifs and compare them with others in the database, particularly those of poxviruses. Two ORFs (RI-35-1 and RI-35-7, respectively) encode putative proteins (113 aa and 219 aa) that are probably involved in regulating gene expression based on their predicted nuclear localization and the presence of SPxx motifs, leucine-zipper like sequences (113 aa), and a basic domain (219 aa). The largest gene (RI-35-3) is under the control of an intermediate/late promoter and is presumed to encode a cytoplasmic 480 aa DNA-dependent DNA helicase with conserved motifs that are characteristic of DExH helicases. Amino acid analysis of the DNA helicase sequence showed that DlEPV is close to but distinct from the Genus B EPVs. The DlEPV helicase is also distinct from that of the Diadromus pulchellus ascovirus 1a from the D. pulchellus parasitic wasp, with less than 10% amino acid identity. DlEPV encodes a 207 aa oligoribonuclease (RI-35-8) of the DEDDh family of exoribonucleases. The second largest ORF (RI-35-9) is under the control of a poxvirus early promoter and encodes a protein of 329 aa that is likely DlEPV-specific. Three ORFs (RI-35-4, -5, and -6) overlap (in the anti-sense strand) with ORFs encoding putatively important virus replication proteins (which were also under the control of intermediate promoters) and are presumably not expressed in DlEPV. These results support earlier reports that DlEPV is a member of the sub-family Entomopoxvirinae, most likely in Group C, and is the first symbiotic EPV described to date from a parasitic wasp.

Molecular cloning and characterization of viruses isolated from chimpanzees with pathogenic human immunodeficiency virus type 1 infections.

We have previously described the development of AIDS in a chimpanzee (C499) infected with human immunodeficiency virus type 1 (HIV-1) and the subsequent pathogenic HIV-1 infection in another chimpanzee (C455) transfused with blood from C499 (F. J. Novembre et al., J. Virol. 71:4086-4091, 1997). In the present study, two virus isolates were derived from these animals: HIV-1JC from peripheral blood mononuclear cells (PBMC) of C499, and HIV-1NC from plasma of C455. These virus isolates were used to generate two infectious molecular clones, termed HIV-1JC16 and HIV-1NC7 (JC16 and NC7, respectively). Comparative analyses of the sequences of the two clones showed that they were highly interrelated but distinct. Based on heteroduplex mobility assays, JC16 and NC7 appear to represent dominant viruses in the uncloned stock population. Compared with amino acid sequences of the parental viruses HIV-1SF2, HIV-1LAV-1b, and HIV-1NDK, JC16 and NC7 showed a number of differences, including insertions, deletions, and point mutations spread throughout the genome. However, insertion/deletion footprints in several genes of both JC16 and NC7 suggested that recombination between SF2 and LAV-1b could have occurred, possibly contributing to the generation of a pathogenic virus. Comparative in vitro analyses of the molecular clones and the uncloned stocks of HIV-1JC and HIV-1NC revealed that these viruses had strikingly similar replicative abilities in mitogen-stimulated PBMC and in macrophages. Compared to the SF2 and LAV-1b isolates of HIV-1, HIV-1JC and HIV-1NC isolates were more similar to LAV-1b with respect to the ability to replicate in mitogen-stimulated PBMC and macrophages. These viruses should prove to be useful in mapping determinants of pathogenesis.

Envelope glycoprotein nucleotide sequence and genetic characterization of North American ovine lentiviruses.

Ovine lentiviruses (OvLV) resemble human immunodeficiency viruses in genomic organization, viral heterogeneity, and spectrum of cytophenotypic expression. To gain a better understanding of the relationship of North American OvLV isolates with other characterized OvLV strains, the complete DNA nucleotide sequence of the env region of a highly lytic (rapid/high) OvLV strain (85/34) was determined and compared with the sequence of amplicons within env of three other OvLV strains of varying cytophenotype and isolated from the same flock of sheep. LTR and pol regions also were compared among these strains. The env region of 85/34 was 986 codons in length and the reported nucleotide sequence showed features shared by other OvLV including heavy glycosylation and conserved and hypervariable regions within the surface membrane protein region. Phylogenetic analyses of regions within LTR, reverse transcriptase, and env grouped the four virus strains together and similar to the maedi-visna OvLV strains, including visna virus, South African ovine maedi visna virus, and EV1 (British OvLV isolate), but they were distinct from caprine arthritis encephalitis virus.