Infection with Possible Novel Parapoxvirus in Horse, Finland, 2013

Abstract

A horse in Finland exhibited generalized granulomatous inflammation and severe proliferative dermatitis. After euthanization, we detected poxvirus DNA from a skin lesion sample. The virus sequence grouped with parapoxviruses, closely resembling a novel poxvirus detected in humans in the United States after horse contact. Our findings indicate horses may be a reservoir for zoonotic parapoxvirus.

Keywords: Clinical; Finland; PCR; dermatitis; equine; granuloma; horse; parapoxvirus; phylogeny; poxvirus; sequence; viruses; zoonosis.

Figure 1

Macroscopic and histologic images of horse infected with possible novel parapoxvirus, Finland, 2013. A) Proliferative and ulcerative skin lesions were seen multifocally on the muzzle, ventral abdomen, and lower limbs (pictured). B) The main histological changes in samples of the skin lesions were severe multifocal lymphohistiocytic dermatitis with marked ballooning degeneration of the stratum granulosum and eosinophilic intrasytoplasmic inclusion bodies in many keratinocytes (arrows). Scale bar indicates 50 μm.

Figure 2

Phylogenetic analyses of sequences amplified from skin lesion of horse infected with possible novel parapoxvirus, Finland, 2013 (poxvirus variant F14.1158H), and other poxviruses. Trees were generated by using the neighbor-joining method in MEGA 6 software (http://www.megasoftware.net) (12), based on A) 184 aa of envelope phospholipase gene and B) 195 aa of viral RNA polymerase gene RP0147. GenBank accession numbers for sequences used in the analyses: JF773701 (Orf virus [ORFV] F07.821R), JF773703 (ORFV F09.1160S), AY386263 (ORFV IA82), AY386264 (ORFV SA00), DQ184476 (ORFV NZ2), GQ329670 (pseudocowpox virus [PCPV] VR634), JF773695 (PCPV F10.3081C), JF773692 (PCPV F07.798R), GQ329669 (PCPV F00.120R), AY453655 (parapoxvirus of red deer in New Zealand [PVNZ] DPV), AY453664 (bovine papular stomatitis virus [BPSV] V660), AY386265 (BPSV AR02), AF414182 (sealpoxvirus [SPV]), U60315 (molluscum contagiosum virus [MOCV] subtype 1), HE601899 (squirrelpox virus [SQPV] red squirrel UK), GQ902051.1 (PCPV 07012), GQ902054.1 (BPSV 07005), KM491712 (2013_013), and KM491713 (2012_037). The final 2 sequences originated from recent cases in humans with equine contacts in the United States (7). The reliability of the trees was determined by 1,000 dataset bootstrap resampling; the percentage of replicate trees in which the associated taxa clustered together is shown in the branches. Scale bars indicate amino acid substitutions per site.