Detection of antibodies against epidermodysplasia verruciformis-associated canine papillomavirus 3 in sera of dogs from Europe and Africa by enzyme-linked immunosorbent assay.

The role of papillomaviruses (PVs) in the development of canine cancers is controversial. However, recently a novel canine PV (CPV3) was detected in a dog affected with a condition reminiscent of epidermodysplasia verruciformis (EV). The aim of the present study was to investigate the seroprevalence of CPV3 by using generic enzyme-linked immunosorbent assays (ELISAs) for the detection of antibodies against either canine oral PV (COPV) or CPV3. Therefore, the capsid proteins of both PV types were expressed as glutathione S-transferase fusion protein antigens and adsorbed to glutathione-casein-coated ELISA plates. After showing that PV type-specific antibodies could be detected in the sera from dogs with confirmed COPV or CPV3 infection, CPV3- and COPV-seropositive samples were detected in two sets of canine sera collected in Switzerland and South Africa, respectively. We found specific antibodies against COPV and CPV3 among the tested sera and also a large number that were positive for both antigens. The seroprevalences of PV antibodies of 21.9% (COPV) and 26.9% (CPV3) among the tested dogs from South Africa were higher than those among the dogs from Switzerland at 10.5% (COPV) and 1.3% (CPV3). Our data suggest a need for further CPV-related seroepidemiological surveys in different countries, especially in the context of clinical manifestations and possible breed predispositions. For this purpose, the newly developed ELISAs can be a useful tool.

Detection of the prototype of a potential novel genus in the family Papillomaviridae in association with canine epidermodysplasia verruciformis.

Epidermodysplasia verruciformis (EV) is a rare human genetic predisposition to develop flat warts, some of which subsequently undergo cancer transformation. Some human papillomaviruses (HPVs), i.e. HPV 5 and 8, have been associated with cancer development as a sequela of EV. As similar diseases have been observed in dogs, it was hypothesized that unknown canine papillomaviruses (CPVs) may exist and that they may be present in cases of canine EV. Consequently, DNA was extracted from a malignant lesion of a dog with EV and circular DNA was amplified by multiple-primed rolling-circle amplification (RCA). Indeed, sequence determination and analysis of the RCA-amplified and cloned DNA from a malignant canine EV lesion resulted in the detection and primary description of a third CPV (CPV3). Typical papillomavirus genes were identified, with deduced amino acid similarities ranging from 20 to 57 % for E1, E2, E6, E7, L1 and L2, respectively. According to the sequence of the L1 gene, which is used for papillomavirus classification, the new isolate meets the majority of criteria needed to declare detection of a novel genus among the papillomaviruses. Thus, CPV3 may represent the prototype of this novel genus. As the novel virus was found in a dog in association with lesions reminiscent of human EV, it should be interesting to test in the future whether this condition can be reproduced in experimental animals. If such were the case, a new model for EV could be established.

Genital papillomaviruses (PVs) and epidermodysplasia verruciformis PVs occur in the same monkey species: implications for PV evolution.

Portions of the genome from two different papillomaviruses (PVs) of the Abyssinian Colobus monkey were sequenced and phylogenetically analyzed. This revealed that the major evolutionary separation between genital PVs and epidermodysplasia verruciformis-associated PVs (EV-PVs) hitherto found only in human papillomaviruses (HPVs) also exists in animal PVs. The sequence of the long control region (LCR) of Colobus monkey PV type 2 (CgPV-2) reveals a small size and an arrangement of potential cis-responsive elements typical of the EV-HPVs; namely four binding sites for the viral E2 protein, with one of them being located within the L1 gene, a cluster of nuclear factor I (NFI)- and AP-1-binding sites and a 50-bp sequence upstream of the E6 gene consisting only of the nucleotides A and T. This level of conservation of functional elements within the highly variable LCR suggests that CgPV-2 could be adopted as a model for studying human skin cancer associated with EV-HPVs. Although isolated from the same monkey species, the other Colobus monkey PV, CgPV-1, is a typical genital PV as shown by E1 and L1 sequence comparisons. The presence of these two major phylogenetic divisions of PVs in both human and monkey hosts strongly suggests that this diversification predated the evolutionary split between monkeys and apes. In other words, at least two different groups of PVs have been evolving separately in their respective primate hosts for more than 22 million years with only moderate sequence changes since their genesis.