Related Experiment Videos
Molecular clones from a non-acutely pathogenic derivative of SIVsmmPBj14: characterization and comparison to acutely
S Dewhurst1, J E Embretson, P N Fultz
1Department of Microbiology and Immunology, University of Rochester Medical Center, NY 14642.
Abstract:
Molecularly cloned simian immunodeficiency viruses capable of inducing acute, fatal disease in pig-tailed macaques had been derived previously from a biological clone (bcl-3) of the PBj14 isolate of SIV from sooty mangabey monkeys (SIVsmmPBj14). The present study was undertaken in order to characterize virus from a second biological clone of SIVsmmPBj14, bcl-1, which fails to induce acute or fatal disease. Polymerase chain reaction was used to amplify 5' and 3' viral genome halves. The DNA sequence of two 3' halves was determined, and an infectious recombinant generated using a bcl-3-derived 5' half and a bcl-1-derived 3' half. Overall, bcl-1- and bcl-3-derived viruses displayed close homology, differing by a total of 2% at the DNA level and 1-6% at the amino acid level within the 8 open reading frames examined. In contrast to the bcl-3-derived viruses, the bcl-1-derived viruses encode a truncated transmembrane envelope glycoprotein. Another consistent difference was the presence of a 22 bp duplication in the U3 portion of the long terminal repeat (LTR) of bcl-3-derived viruses that includes the NF-kappa B transcriptional enhancer binding site. To assess the importance of this duplication, virus chimeras were generated which removed the duplication from the 3'-LTR or from both LTRs of a bcl-3 clone. The former virus was unstable, reacquiring the duplication through recombination with the 5' LTR. No consistent difference were observed, however, between viruses with or without the duplication in the in vitro studies conducted to date.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Researchers characterized simian immunodeficiency virus (SIV) clones from sooty mangabey monkeys (SIVsmmPBj14). They found differences in viral envelope glycoproteins and long terminal repeat (LTR) sequences, impacting disease induction in macaques.
Area of Science:
- Virology
- Molecular Biology
- Primate Immunology
Background:
- Simian immunodeficiency virus (SIV) from sooty mangabey monkeys (SIVsmmPBj14) can cause fatal disease in pig-tailed macaques.
- Previous studies derived pathogenic SIV clones (bcl-3) from SIVsmmPBj14.
Purpose of the Study:
- To characterize a non-pathogenic SIV clone (bcl-1) from SIVsmmPBj14.
- To identify genetic differences between pathogenic (bcl-3) and non-pathogenic (bcl-1) SIV clones.
- To investigate the role of specific genetic elements in SIV pathogenicity.
Main Methods:
- Polymerase chain reaction (PCR) amplification of viral genome halves.
- DNA sequencing of viral genome fragments.
- Generation of infectious recombinant viruses.
- Construction of virus chimeras to study specific genetic elements.
Main Results:
- SIV bcl-1 and bcl-3 clones showed high genetic homology (2% DNA, 1-6% amino acid differences).
- Non-pathogenic bcl-1 viruses encoded a truncated transmembrane envelope glycoprotein.
- Pathogenic bcl-3 viruses possessed a 22 bp duplication in the U3 region of the long terminal repeat (LTR), including the NF-kappa B enhancer.
- Virus chimeras lacking the LTR duplication were unstable or showed no consistent differences in in vitro studies.
Conclusions:
- Genetic variations, including envelope glycoprotein truncation and LTR duplications, distinguish pathogenic and non-pathogenic SIV strains.
- The NF-kappa B enhancer duplication in the LTR may play a role in SIV pathogenicity, though its precise function requires further investigation.
- Further research is needed to fully elucidate the molecular mechanisms underlying SIV-induced disease in macaques.