Biology subjects
Publications and source records attributed to Canuti, M..
A parvovirus recently associated with an outbreak in Dutch pigs was found in Denmark in symptomatic pigs and in fox (Vulpes vulpes) feces and spleens. Pig viruses were more closely related to each other than to viruses found in the respective local wildlife, suggesting a link between the farm outbreaks.
Several pathogens are known to affect the respiratory tract of pigs resulting in decreased health and welfare. Virological investigations and the use of metagenomic sequencing of samples allowed the identification of new viruses in pigs, such as porcine respirovirus type 1 (PRV1) and swine orthopneumovirus (SOV). The pathogenicity of PRV1 has been investigated experimentally by one research group, whereas SOV is yet to be studied. In this experimental trial, groups of weaners were inoculated with a European isolate of PRV1 (n = 8), a pool of SOV RNA-positive clinical nasal swab material (n = 8) or culture medium serving as controls (n = 4). Four days post inoculation (DPI), two controls and four pigs from each of the PRV1 and SOV groups were euthanized and necropsied. All SOV inoculated pigs tested negative for SOV at DPI 4 and therefore four of these pigs were transferred to the stable with the PRV1- infected pigs to assess direct-contact transmission. Nasal swab samples were collected at regular intervals after challenge and blood samples were collected at DPI 0, 4, and 14. At 14 DPI, the remaining pigs (n = 10) were euthanized and necropsied. Nasal swab samples and tissues from the respiratory tract were examined for PRV1 RNA by reverse transcriptase real- time PCR and blood samples were investigated for PRV1 antibodies by ELISA. Respiratory tissues were also evaluated macro- and microscopically and selected tissues were investigated for in situ detection of PRV1 mRNA by RNAscope. No clinical signs, except for nasal discharge, were observed in any of the pigs. PRV1-shedding was observed from DPI 2 to 11 with peaks between DPI 4 and 7, and PRV1 was transmitted horizontally to all direct-contact pigs. The highest viral load was detected in the upper respiratory tract, i.e. nose, upper and lower trachea compared to the lower respiratory tract, i.e., bronchioles, and alveoli. Generally, a chronic tracheitis at 4 DPI, developing into chronic, erosive tracheitis at 14 DPI was observed in the PRV1 groups and was supported by in situ detection of PRV1 by RNAscope. Three pigs also developed mild, bronchointerstitial pneumonia at 14 DPI. In conclusion, these results showed that PRV1 is a primary porcine respiratory pathogen. Author summaryRespiratory diseases in pigs impair porcine health and welfare and are often caused by a complex interaction between pathogens. We investigated the pathogenesis of two recently discovered viruses: porcine respirovirus type 1 (PRV1) and swine orthopneumovirus (SOV). An experimental model in weaner pigs showed that PRV1 is capable of efficient replication, horizontal transmission and caused pathological manifestations mainly in the upper respiratory tract. The lesions consisted of chronic, erosive tracheitis in all PRV1 infected pigs, resulting in a breakage of the tracheal epithelial barrier, and a few pigs developed bronchointerstitial pneumonia. These findings confirm that PRV1 should be considered a primary porcine respiratory pathogen, but in contrast, SOV did not result in a successful infection, and the reasons why remain to be elucidated. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=100 SRC="FIGDIR/small/666573v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@d93a11org.highwire.dtl.DTLVardef@17341e9org.highwire.dtl.DTLVardef@1ec4ca4org.highwire.dtl.DTLVardef@9bd42f_HPS_FORMAT_FIGEXP M_FIG C_FIG Graphical abstract created with Biorender.com
Canine circoviruses (CanineCV) have a worldwide distribution in dogs and are occasionally detected in wild carnivorans, indicating their ability for cross-species transmission. However, fox circovirus, a lineage of CanineCV, has been identified exclusively in wild canids. We analyzed spleen samples from 159 grey wolves from the Northwest Territories, Canada, to investigate the molecular epidemiology of CanineCV and formulate hypotheses about virus ecology and evolution. Overall, 72 out of 159 (45.3%) animals tested positive. Virus prevalence was similar between males and females, adults and juveniles, and across the investigated years and locations. CanineCV infection was not associated with a poor body condition. While the percentage of co-infections with canine parvoviruses, investigated in a previous study, was high (63/72, 87.5%), the rate of parvovirus infection in CanineCV-negative animals was significantly lower (42/87, 48.3%, {chi}2 = 27.03, p < 0.001), and CanineCV infection was associated with a 7.5- and 2.4-fold increase in the risk of acquiring canine parvovirus 2 or canine bufavirus infections, respectively (odds ratios: 3.5-16.9 and 1.3-5.8). Although common risk factors cannot be ruled out, this suggests that CanineCV may facilitate parvoviral super-infections. Sequencing revealed high CanineCV genetic diversity, further exacerbated by recombination. Of the 69 sequenced strains, 87.5% were fox circoviruses, five were related to a fox circovirus-like recombinant strain, and one belonged to a distant lineage. In the phylogenetic analysis, the virus sequences were distributed according to sampling locations, with some viruses being geographically restricted. Different clades of viruses were identified in the same areas and over multiple years (2007-2019), indicating the co-existence of multiple endemic lineages in the investigated area. Phylogenetic analysis of all available complete fox circovirus genomes (32 from foxes and 15 from wolves from North America and Europe) demonstrated four lineages, each including sequences from this study. Within each lineage, strains segregated geographically and not by host. This implies that, although multiple lineages co-exist, viruses do not frequently move between locations. Finally, viruses from Europe and North America were mixed, indicating that the origin of the four lineages might predate the segregation of European and American wolf and fox populations. Given the high prevalence and diversity of fox circoviruses in wolves, these animals should be considered reservoir hosts for these viruses. Although we cannot exclude a lower susceptibility of dogs, the lack of fox circovirus in dogs could be due to environmental circumstances that prevented its spread to dogs. Given the high diversity and wild host specificity, we presume a long-lasting association between fox circovirus and canine hosts and hypothesize a higher likelihood of transmission from dogs to wild animals than vice versa. Further studies should investigate other sympatric wild species and additional locations to explore the possible existence of additional maintenance hosts and the reasons behind the marked difference in cross-species transmission dynamics among CanineCV lineages.
Gammaherpesviruses (GHVs) infect many animal species and are associated with lymphoproliferative disorders in some. Previously, we identified several novel GHVs in North American felids, however a GHV had never been identified in Canada lynx (Lynx canadensis). We therefore hypothesized the existence of an unidentified GHV in lynx. Using degenerate nested and subsequently virus-specific PCR, we amplified and sequenced 3.4 kb of DNA from a novel GHV in lynx, which we named Lynx canadensis gammaherpesvirus 1 (LcaGHV1). We then estimated the prevalence of LcaGHV1 in lynx by developing a PCR-based assay and detected LcaGHV1 DNA in 36% (95% CI: 22-53%) of lynx spleen DNA samples from Maine, USA and 17% (95% CI: 8-31%) from Newfoundland, Canada. Phylogenetic analysis determined that LcaGHV1 is a distinct GHV species belonging to the genus Percavirus. The potential ecologic and pathologic consequences of this novel virus for Canada lynx populations warrant further study.