Discovery of a novel simian pegivirus in common marmosets (Callithrix jacchus) with lymphocytic enterocolitis

From 2010 to 2015, 73 common marmosets (Callithrix jacchus) housed at the Wisconsin National Primate Research Center (WNPRC) were diagnosed postmortem with lymphocytic enterocolitis. We used unbiased deep-sequencing to screen the blood of deceased enterocolitis-positive marmosets for the presence of RNA viruses. In five out of eight marmosets with lymphocytic enterocolitis, we discovered a novel pegivirus that was not present in ten subsequently deep-sequenced matched, clinically-normal common marmosets with no evidence of lymphocytic enterocolitis. The novel virus, which we have named Southwest bike trail virus (SOBV), is most closely related (68% nucleotide identity) to a strain of simian pegivirus A that was previously isolated from a three-striped night monkey (Aotus trivirgatus). To determine the prevalence of this novel virus within the WNPRC marmoset colony, we screened 146 living animals and found an overall prevalence of 34% (50/146). Over the next four years, 85 of the 146 screened marmosets died or were euthanized and were examined histologically for lymphocytic enterocolitis. Out of these 85 animals, 27 SOBV-positive common marmosets had developed lymphocytic enterocolitis, compared to 42 SOBV-negative common marmosets, indicating no evidence of an association between this virus and development of enterocolitis in this cohort (p=0.0798). The novel pegivirus was also found in two of 32 (6%) clinically-normal common marmosets screened while in quarantine during the transfer from the New England Primate Research Center to the WNPRC, suggesting SOBV has different prevalence at different centers and could exert confounding influences on the comparison of marmoset studies from multiple centers. ImportanceCommon marmosets (Callithrix jacchus) are a valuable model species. We discovered two variants of a novel simian pegivirus, which we named the Southwest bike trail virus (SOBV), in common marmosets which had postmortem histologic diagnosis of lymphocytic enterocolitis. The virus was not present in ten matched, clinically-normal controls. We screened 146 live healthy common marmosets in the Wisconsin National Primate Research Center colony and found 34% (50/146) of the animals were SOBV-positive. SOBV was also present in two of 32 (6%) clinically-normal common marmosets from the New England Primate Research Center. These findings could have confounding effects in animal studies, especially those in which infection-free animals are desired, and they demonstrate the need for further investigations into SOBV transmission, the length of time of SOBV persistence, and SOBV prevalence at other primate centers, in order to increase understanding of the effects of SOBV and of this viral genus.