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

Luise Krüger,Lena Katharina Neubert,Joachim Denner,Vanessa Schröder,Milena Stillfried,Carolin Prinz

doi:10.3390/v12040419

Luise Krüger, Lena Katharina Neubert + Show 4 more

Open Access

https://doi.org/10.3390/v12040419

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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.

Highlights

Endogenous retroviruses are the result of infection and integration of ancient retroviruses into the germ line of a host
porcine endogenous retroviruses (PERVs)-A and PERV-B were found by PCR using specific primers for the PERV-Aenv and PERV-Benv sequences in all wild boars, their prevalence was 100%
The integration of the proviruses was demonstrated by a new method which is equivalent to the Southern blot analysis; PERV integration was demonstrated by PCR detection of viral sequences in high molecular weight fractions of pig DNA

Summary

Introduction

Endogenous retroviruses are the result of infection and integration of ancient retroviruses into the germ line of a host. They are widely distributed in many species including humans and play an important role in placentogenesis [1]. All three viruses belong to the genus gammaretroviruses and they differ in their envelope protein, mainly in the receptor-binding domain and in the receptor usage. They are highly related in the gag and pol sequences but differ in the sequence of the long terminal repeats (LTR), as well as in the age of integration and the prevalence among pigs. PERV-A and PERV-C have the same origin and are younger compared to PERV-B

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Discussion

Conclusion