Copy Number and Prevalence of Porcine Endogenous Retroviruses (PERVs) in German Wild Boars

Abstract

Porcine endogenous retroviruses (PERVs) are integrated in the genome of pigs and are transmitted like cellular genes from parents to the offspring. Whereas PERV-A and PERV-B are present in all pigs, PERV-C was found to be in many, but not all pigs. When PERV-C is present, recombination with PERV-A may happen and the PERV-A/C recombinants are characterized by a high replication rate. Until now, nothing has been known about the copy number of PERVs in wild boars and little is known about the prevalence of the phylogenetically youngest PERV-C in ancient wild boars. Here we investigated for the first time the copy number of PERVs in different populations of wild boars in and around Berlin using droplet digital PCR. Copy numbers between 3 and 69 per genome have been measured. A lower number but a higher variability was found compared to domestic pigs, including minipigs reported earlier (Fiebig et al., Xenotransplantation, 2018). The wild boar populations differed genetically and had been isolated during the existence of the Berlin wall. Despite this, the variations in copy number were larger in a single population compared to the differences between the populations. PERV-C was found in all 92 analyzed animals. Differences in the copy number of PERV in different organs of a single wild boar indicate that PERVs are also active in wild boars, replicating and infecting new cells as has been shown in domestic pigs.

Copy Number Variations Contribute to Intramuscular Fat Content Differences By Affecting The Expression of PELP1 Alternative Splices in Pig

“…Fowler et al (2013) found a CNV region related to backfat thickness on chromosome 7 using a pig 60K Beadchip [10]. In the research of Revilla et 2020), CNVs were reported to be associated with fatty acid composition and growth traits, ear size, number of piglets born alive, and prevalence of porcine endogenous retroviruses [11][12][13][14]. In our previous research, CNVRs have reported associated with IMF content [15].…”

Porcine Endogenous Retroviruses and Xenotransplantation, 2021

“…The copy number of PERVs in the genome of pigs; e.g., the number of integrated proviruses, differs depending on the pig strain, the age of the animals, the organ analyzed, and the method used for detection (for review, see [66]). The PERV copy number per cell in Göttingen and Aachen minipigs as measured by ddPCR varies around 50 and 70 [59,67]; the number PERV copies of German landrace pigs genetically modified to be used in xenotransplantation and wild boars are in the same range, from 50 to 70 [67,68]. These are the copy numbers of integrated proviruses when analyzing high-molecularweight DNA, not episomal DNA.…”

High Prevalence of Recombinant Porcine Endogenous Retroviruses (PERV-A/Cs) in Minipigs: A Review on Origin and Presence

“…An extensive testing for PERV-A/C was not performed in other swine breeds than minipigs. In some cases, such a testing was performed and the results were negative: examples are wild boars [ 70 , 71 ] and Large White animals [ 71 ]. Further studies have been conducted in genetically modified animals generated for xenotransplantation purpose: PERV-A/C recombinants were only found in animals with a minipig proportion in their genome, e.g., in Large White/Duroc/Minipigs (15 out of 28 animals found positive) and in Large White/German Landrace/Duroc/Minipigs (three of five animals found positive) [ 71 ].…”