Cloned endogenous retroviral sequences from human DNA

Area of Science:

• Molecular Biology
• Genomics
• Evolutionary Biology

Background:

• Endogenous retroviruses (ERVs) are remnants of ancient viral infections integrated into host genomes.
• Comparative genomics can reveal evolutionary relationships and ancient genetic elements.
• Human and primate genomes harbor diverse retroviral sequences of varying evolutionary ages.

Purpose of the Study:

• To identify and characterize novel human endogenous retroviral sequences.
• To investigate the evolutionary origins and conservation of specific retroviral elements in primates.
• To determine the genomic copy number and chromosomal location of a newly identified human retroviral sequence.

Main Methods:

• Screening of a human DNA library using a chimpanzee retroviral probe.
• DNA sequencing and sequence homology analysis of cloned human DNA fragments.
• Hybridization of cloned DNA to human genomic DNA digests (Southern blotting).

Main Results:

• A 20-kilobase human DNA sequence with homology to baboon endogenous virus polymerase gene was identified.
• The human sequence contains homologous regions to gag p30, gag p15, and polymerase genes of Moloney murine leukemia virus, with conserved spacing.
• The human genome contains two closely related copies and approximately ten less related copies of this retroviral sequence.
• Identical 3' flanking sequences in human and chimpanzee clones suggest the retroviral element predates human-chimpanzee divergence.

Conclusions:

• A novel human endogenous retroviral sequence, sharing homology with known retroviruses, has been identified.
• The conserved structure and flanking sequences indicate this retroviral element is ancient and shared between humans and chimpanzees.
• This finding provides insights into the integration and evolutionary history of retroviruses in primate genomes.