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Updated: Sep 26, 2026
Isolation of Exosomes from the Plasma of HIV-1 Positive Individuals
Published on: January 5, 2016
Isolation and characterization of a novel protein (X-ORF product) from SIV and HIV-2
L E Henderson1, R C Sowder, T D Copeland
1Bionetics Research, Inc., National Cancer Institute, Frederick, MD 21701.
Abstract:
A protein designated p14 was purified from a simian immunodeficiency virus (SIVMne) and was shown by amino acid sequence analysis to be nearly identical to the predicted translational product of a unique open reading frame (X-ORF) in the nucleotide sequences of SIVmac and human immunodeficiency virus type 2 (HIV-2). Thus the X-ORF is proven to be a new retroviral gene. The p14 is present in SIVMne in molar amounts equivalent to those of the gag proteins. This is the first example of a retrovirus that contains a substantial quantity of a viral protein that is not a product of the gag, pro, pol, or env genes. SIV p14 and its homolog in HIV-2 may function as nucleic acid binding proteins since purified p14 binds to single-stranded nucleic acids in vitro. Antisera to the purified protein detected p14 in SIVMne, SIVmac, and a homologous protein (16 kilodaltons) in HIV-2 but did not react with HIV-1. Diagnostic procedures based on this novel protein will distinguish between HIV-1 and HIV-2.
Insights
Researchers discovered a novel retroviral gene, the X-Open Reading Frame (X-ORF), in simian immunodeficiency virus (SIV) and human immunodeficiency virus type 2 (HIV-2). This gene encodes a p14 protein, crucial for distinguishing between HIV-1 and HIV-2.
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Simian immunodeficiency virus (SIV) and human immunodeficiency virus type 2 (HIV-2) share genetic similarities.
- Retroviral genomes typically contain gag, pro, pol, and env genes.
- The existence of additional viral genes was previously unconfirmed.
Purpose of the Study:
- To identify and characterize novel genes within retroviral genomes.
- To investigate the function and prevalence of the newly identified X-Open Reading Frame (X-ORF) protein.
- To explore the potential of this protein in diagnostic applications.
Main Methods:
- Purification of the p14 protein from SIV.
- Amino acid sequence analysis for protein identification.
- Nucleotide sequence analysis of SIV and HIV-2 genomes.
- In vitro nucleic acid binding assays.
- Antisera production and Western blot analysis.
Main Results:
- A novel retroviral gene, X-ORF, was identified in SIV and HIV-2.
- The X-ORF encodes a p14 protein, found in molar amounts comparable to gag proteins.
- Purified p14 protein demonstrated nucleic acid binding capabilities in vitro.
- Antisera detected p14 in SIV and a homologous protein in HIV-2, but not in HIV-1.
Conclusions:
- The X-ORF represents a newly discovered retroviral gene.
- The p14 protein is a significant viral component, potentially involved in nucleic acid binding.
- This novel protein can serve as a reliable marker for differentiating HIV-1 from HIV-2.
