Distribution and expression of chicken endogenous retroviruses in the host genome

Abstract

The distribution of seven groups of endogenous retroviruses (ALV-related ev loci, HERV-I-related proviruses, EAV-HP, EAV-0, E-33, E-51, ART-CH) in the genome of domestic chicken (Gallus gallus) was studied according to the composition (long-range variation of GC-content) of the host genome. GC-rich proviruses (ev loci, ART-CH and EAV-0) have been localized mainly in GC-richest isochore families H2, H3 and H4, GC-poor HERV-I-related proviruses, E-51 and E-33 localized in GC-poor isochore families LI, L2 and also in HI (isopycnicity). GC-rich EAV-HP, except expected distribution GC-rich isochores, present also in GC-poor compartments. Investigation of expression by RT-PCR and analysis of EST databases provided a tissue-specific patterns that could change the picture of proviral distribution due to reintegration. Reasons of endogenous retrovirus isopycnicity are likely to be the compositional match between the integrant and the chromosomal region of the host, that led to the stability of integration.