Molecularly Cloned SHIV-1157ipd3N4: a Highly Replication- Competent, Mucosally Transmissible R5 Simian-Human Immunodeficiency Virus Encoding HIV Clade Cenv

Abstract

Human immunodeficiency virus type 1 (HIV-1) clade C causes >50% of all HIV infections worldwide, and an estimated 90% of all transmissions occur mucosally with R5 strains. A pathogenic R5 simian-human immunodeficiency virus (SHIV) encoding HIV clade C env is highly desirable to evaluate candidate AIDS vaccines in nonhuman primates. To this end, we generated SHIV-1157i, a molecular clone from a Zambian infant isolate that carries HIV clade C env. SHIV-1157i was adapted by serial passage in five monkeys, three of which developed peripheral CD4 ؉ T-cell depletion. After the first inoculated monkey developed AIDS at week 137 postinoculation, transfer of its infected blood to a naïve animal induced memory T-cell depletion and thrombocytopenia within 3 months in the recipient. In parallel, genomic DNA from the blood donor was amplified to generate the late proviral clone SHIV-1157ipd3. To increase the replicative capacity of SHIV1157ipd3, an extra NF-B binding site was engineered into its 3 long terminal repeat, giving rise to SHIV1157ipd3N4. This virus was exclusively R5 tropic and replicated more potently in rhesus peripheral blood mononuclear cells than SHIV-1157ipd3 in the presence of tumor necrosis factor alpha. Rhesus macaques of Indian and Chinese origin were next inoculated intrarectally with SHIV-1157ipd3N4; this virus replicated vigorously in both sets of monkeys. We conclude that SHIV-1157ipd3N4 is a highly replication-competent, mucosally transmissible R5 SHIV that represents a valuable tool to test candidate AIDS vaccines targeting HIV-1 clade C Env.

Heterologous Prime/Boost Immunization of Rhesus Monkeys by Using Diverse Poxvirus Vectors

“…Both the R5-tropic and clade C SHIVs that have been developed cause infections in macaques with peak and set point plasma viral RNA levels that are too variable to allow a useful comparison of different vaccine strategies (12,26). The clade B SHIV-89.6P acts in vivo like a CXCR4-tropic virus and preferentially eliminates naïve CD4 ϩ T lymphocytes, while HIV-1 usually infects CCR5-expressing CD4…”

Generation of Recombinant Vaccinia Viruses via Green Fluorescent Protein Selection

“…An expression vector containing IRES and the GFP gene, pIRES2-EGFP, was purchased from Clontech Laboratories (Mountain View, CA). A recombinant plasmid encoding a mutant HIV envC was created by subcloning SHIV-1157ip env (Song et al, 2006) into vector pJW4303 and subsequent site-directed mutagenesis to remove the variable loops V1-V3; the plasmid was propagated in Escherichia coli strain DH5a (Invitrogen, Carlsbad, CA).…”

“…As a test gene of interest, we chose a mutant version of env derived originally from a primary strain of human immunodeficiency virus (HIV) clade C, termed envC (Song et al, 2006). The envC and GFP genes were separated by IRES and positioned under the control of the VV early-late synthetic promoter in the VV insertion vector pSC59 (Chakrabarti et al, 1997).…”

Isolate-Specific Differences in the Conformational Dynamics and Antigenicity of HIV-1 gp120

“…Four Env isolates with widely divergent phenotypes were compared (Table 1): SF162 (42), HXB2 (43), 1084i (44), and 1157ip (45). These isolates are derived from clades B and C, exhibit differences in coreceptor usage, vary in their sensitivity to neutralization by the CD4 binding site-directed antibody IgG1-b12, and exhibit a range of variable loop lengths and number of potential N-linked glycosylation sites (PNGS) ( Table 1).…”