Recombination analysis of human-tropic porcine endogenous retroviruses

Abstract

Prevention of cross-species infection of porcine endogenous retroviruses (PERV) is crucial for xenotransplantation. The potential risk of infection is caused by replication-competent PERV as well as by hybrid viruses derived from recombination events of distinct PERV genomes. Recently, human-tropic, replication-competent PERV genomes obtaining hybrid sequences have been observed. Here, complete polymorphism pattern analysis was performed on the full-length PERV c1 clones and on the complete envelope (env) gene sequences published to date. Several recombined full-length clones and a high number of different recombination patterns in the env gene were identified. In addition, recombinations with retroviral genomes not yet known were found. Thus, the potential risk of infection also exists for recombination products, including defective PERV loci.

Evolutionary Spread and Recombination of Porcine Endogenous Retroviruses in the Suiformes

“…There was no detectable recombination event between PERV-B and either PERV-A or PERV-C in the samples (data not shown), but recent publications of PERV sequences suggest that the different PERV classes still recombine (20,49).…”

Evidence and Consequence of Porcine Endogenous Retrovirus Recombination

“…Each of these recombined env genes had different A-to-C crossover points (Fig. 4), while at least three recombination patterns have been found for C-to-A recombination upstream of the RBD (18,28). It is, therefore, most likely that these A/C recombinant PERV, which are genetically distinct from each other, have arisen in individual pigs, since such A/C recombinant env sequences have also been found in nonstimulated porcine PBMC (56).…”

“…Finally, the significance of BQOne's separation from the rest of PERV-B in IN (Fig. 3E; also noted in a previous study [18]) is not clear, because this sequence was created by multiple PCR cloning from a cDNA library (39) and was, therefore, potentially more susceptible to technical artifacts. The IN region appears to be most conserved as indicated by the data shown in Fig.…”

“…Notably, data from partial sequencing of the PERV genome revealed evidence for possible recombination events (28,40,55) but not a genetic characterization of the whole genome of recombinant PERV. In contrast, studies analyzing longer genome sequences (17)(18)(19) have not directly linked genetic recombination with its effect on biological activity of PERV.…”

Isolation and Characterization of an Infectious Replication-Competent Molecular Clone of Ecotropic Porcine Endogenous Retrovirus Class C

“…Statistical analyses describe the positions of recombination events between the different PERV classes (7,8). One recombinant, PERV-A/C, was characterized in detail (2, 6).…”