Human retroviral sequences on the Y chromosome

Area of Science:

• Genetics
• Molecular Biology
• Virology

Background:

• Endogenous human retroviruses (HERVs) are remnants of ancient retroviral infections integrated into the host genome.
• Understanding HERV sequences, particularly those on sex chromosomes, is crucial for insights into genome evolution and potential functions.

Purpose of the Study:

• To clone and characterize novel endogenous human retroviral sequences.
• To determine the chromosomal location and origin of these newly identified HERV sequences.

Main Methods:

• Low-stringency hybridization using the pol gene of endogenous human retrovirus 51-1.
• Cloning of retroviral sequences, including gag, pol, env, and long terminal repeat (LTR) regions.
• Genomic Southern blotting of male and female DNA to identify chromosomal location.

Main Results:

• A novel HERV clone, lambda NP-2, was isolated, containing gag, pol, env, and LTR sequences.
• The env gene sequence of NP-2 showed 73% homology to endogenous human retrovirus 4-1.
• Genomic Southern blots confirmed NP-2 is located on the Y chromosome, with another related sequence also present on the Y chromosome.
• Conservation of flanking DNA suggested a gene duplication event for the second Y chromosome copy of the NP-2 env sequence.

Conclusions:

• Novel HERV sequences, including a functional env gene, are present on the human Y chromosome.
• The Y chromosome harbors at least two related HERV env sequences.
• Evidence suggests that the duplication of these Y-linked HERV sequences occurred via gene duplication rather than provirus insertion.