Endogenous retroviral sequences in the pig genome represent a potential infectious risk in xenotransplantation. Porcine endogenous retrovirus (PERV) γ sequences described to date have been classified into several families. The known infectious, human-tropic PERVs have been assigned to the PERV γ1 subfamilies A, B and C. High copy numbers and full-length clones have also been observed for an additional family, designated PERV γ2. The aim of this study was to examine the PERV γ2 family by analysis of retroviral pro/pol gene sequences. The proviral load was observed to be similar among various pig breeds. Although clones harbouring an open reading frame in the examined region were found, analysis of published large PERV γ2 clones revealed multiple deleterious mutations in each of the retroviral genes. Various recombination events between γ2 genomes were revealed. In contrast to PERV γ1, phylogenetic analyses did not distinguish defined subfamilies, but indicated the independent evolution of the proviruses after a single event of retroviral amplification. Expression analysis showed large PERV γ2 transcripts and variable transcription in several tissues. Analysis of the two published γ2 env gene sequences observed the partial lack of the receptor-binding domain. Overall, this study indicated the low infectious potential for PERV γ2.
AnderssonA.-C.,
VenablesP. J. W.,
TönjesR. R.,
SchererJ.,
ErikssonL.,
LarssonE.2002; Developmental expression of HERV-R (ERV3) and HERV-K in human tissue. Virology 297:220–225[CrossRef]
BeckmannJ. P.,
BremG.,
EiglerF. W.,
GünzburgW.,
HammerC.,
Müller-RuchholtzW.,
Neumann-HeldE. M.,
SchreiberH.-L.2000Xenotransplantation von Zellen, Geweben oder Organen Berlin: Springer (in German;
BénitL.,
DessenP.,
HeidmannT.2001; Identification, phylogeny, and evolution of retroviral elements based on their envelope genes. J Virol 75:11709–11719[CrossRef]
BlondJ.-L.,
LavilletteD.,
CheynetV.,
BoutonO.,
OriolG.,
Chapel-FernandesS.,
MandrandB.,
MalletF.,
CossetF.-L.2000; An envelope glycoprotein of the human endogenous retrovirus HERV-W is expressed in the human placenta and fuses cells expressing the type D mammalian retrovirus receptor. J Virol 74:3321–3329[CrossRef]
de ParsevalN.,
LazarV.,
CasellaJ.-F.,
BenitL.,
HeidmannT.2003; Survey of human genes of retroviral origin: identification and transcriptome of the genes with coding capacity for complete envelope proteins. J Virol 77:10414–10422[CrossRef]
HallT. A.1999; BioEdit: a user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT. Nucleic Acids Symp Ser 41:95–98
HuderJ. B.,
BöniJ.,
HattJ.-M.,
SoldatiG.,
LutzH.,
SchüpbachJ.2002; Identification and characterization of two closely related unclassifiable endogenous retroviruses in pythons ( Python molurus and Python curtus ). J Virol 76:7607–7615[CrossRef]
LeeJ.-H.,
WebbG. C.,
AllenR. D. M.,
MoranC.2002; Characterizing and mapping porcine endogenous retroviruses in Westran pigs. J Virol 76:5548–5556[CrossRef]
MangR.,
MaasJ.,
ChenX.,
GoudsmitJ.,
van der KuylA. C.2001; Identification of a novel type C porcine endogenous retrovirus: evidence that copy number of endogenous retroviruses increases during host inbreeding. J Gen Virol 82:1829–1834
Marchler-BauerA.,
AndersonJ. B.,
CherukuriP. F.& 21 other authors2005; CDD: a Conserved Domain Database for protein classification. Nucleic Acids Res 33:D192–D196[CrossRef]
MiS.,
LeeX.,
LiX.-P.& 9 other authors2000; Syncytin is a captive retroviral envelope protein involved in human placental morphogenesis. Nature 403:785–789[CrossRef]
OldmixonB. A.,
WoodJ. C.,
EricssonT. A.,
WilsonC. A.,
White-ScharfM. E.,
AnderssonG.,
GreensteinJ. L.,
SchuurmanH.-J.,
PatienceC.2002; Porcine endogenous retrovirus transmission characteristics of an inbred herd of miniature swine. J Virol 76:3045–3048[CrossRef]
PatienceC.,
SwitzerW. M.,
TakeuchiY.,
GriffithsD. J.,
GowardM. E.,
HeneineW.,
StoyeJ. P.,
WeissR. A.2001; Multiple groups of novel retroviral genomes in pigs and related species. J Virol 75:2771–2775[CrossRef]
TönjesR. R.,
NiebertM.2003; Relative age of proviral porcine endogenous retrovirus sequences in Sus scrofa based on the molecular clock hypothesis. J Virol 77:12363–12368[CrossRef]
TristemM.2000; Identification and characterization of novel human endogenous retrovirus families by phylogenetic screening of the human genome mapping project database. J Virol 74:3715–3730[CrossRef]
van RegenmortelM. H. V.,
FauquetC. M.,
BishopD. H. L.
, 8 other editors. 2000; Virus Taxonomy: the Classification and Nomenclature of Viruses
. Seventh Report of the International Committee on Taxonomy of Viruses San Diego: Academic Press;