Identification of swinepox virus from natural outbreaks in pig population of Assam

Abstract

Outbreaks of swinepox [caused by a swinepox virus (SWPV)] in pigs were investigated in 3 districts of Assam, a north eastern state of India. Diagnosis of the disease was carried out employing both standard virological as well as molecular methods. Three representative isolates from different places were selected for inoculation into confluent monolayers of Porcine Kidney-15 (PK-15) cell line. The cytopathic effects were characterized by cell rounding, nuclear vacuolation, cell fusion, granulation of cells and finally detachment from third blind passage onwards. The three genes viz., SPV18-20 and P42 of SWPV was targeted for confirmation of the virus. Swinepox virus was successfully adapted to the PK-15 cell line from seventh passage onwards. The isolated viruses were characterized by sequencing and phylogenetic analysis of P42 gene (extracellular envelope protein), a homologue of vaccinia virus F13L gene. In India, studies on swine pox are very limited. This is the first report on successful isolation of swinepox virus from north eastern region of India. Assam and the other north-eastern states of India being a hub for pig husbandry, isolation of swinepox virus will help in developing and formulating control strategies against the disease.

Primary skin diseases and cutaneous manifestations of systemic diseases in swine

“…Swinepox corresponded to 5.8% of our diagnoses, in a study on swine diseases, it corresponded to 0.2% of the infectious and parasitic diseases diagnosed (Brum et al 2013). This disease is caused by a poxvirus, has a wide distribution and outbreaks have already been described in São Paulo (Bersano et al 2003, Medaglia et al 2011, Tocantins (Bersano et al 2003), in the Brazilian northeast (Olinda et al 2016), Italy (Mariano et al 2015) and India (Mech et al 2018). The histological aspects were similar to those described by Olinda et al (2016), of the nine cases, in eight, viral infection was associated with histological lesions suggestive of allergic dermatitis, suggesting the theory that Haematopinus suis lice and flies may be mechanical vectors for the transmission of the swinepox virus (Torrison & Cameron 2019).…”

First Report of Swinepox in a Wild Boar in Italy: Pathologic and Molecular Findings

“…The macroscopic aspect of SWPV infection has been described as a multifocal, eruptive dermatitis, commonly affecting the abdomen, inner surface of the legs, pinnae and occasionally the snout, vulva and back [ 9 , 10 , 13 ]. The development of a generalized disease, with lesions affecting the whole body, has been reported for suckling piglets [ 2 ], as observed in the described case.…”

“…It has been hypothesized that the main lesions, observed on the abdomen and inner surface of the legs, including the udder and vulva, correspond to the predilection sites of the pig louse [ 1 ]. Secondary bacterial infections, facilitated by SWPV infection and disruption of skin epithelium, lead to more severe lesions and formation of local abscesses [ 2 , 10 ]. According to the literature, clinical lesions are generally restricted to the skin, with occasional mild changes in the superficial lymph nodes [ 1 ].…”

“…Its main mode of transmission is through the biting of the pig louse Haematopinus suis , which acts as a mechanical vector; however, direct animal contact and congenital transmission have also been reported [ 2 , 3 , 4 ]. Swinepox was first described as a disease of domestic pigs in Europe in 1842 [ 5 ] and in the USA in 1929 [ 6 ], but outbreaks have subsequently been found in pigs also in Africa, Asia, Australia and South America [ 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. It is commonly associated with poor sanitation [ 4 ], since the virus shows a high environmental stability and is very resistant to drying, as all poxviruses are [ 14 ].…”

Swinepox Virus Strains Isolated from Domestic Pigs and Wild Boar in Germany Display Altered Coding Capacity in the Terminal Genome Region Encoding for Species-Specific Genes

“…This virus contains a linear double-stranded DNA genome of 146 kbp and is the etiological agent of an eruptive dermatitis in pigs, known as swinepox. Swinepox was first described as a disease of domestic pigs in Europe in 1842 [1] and in the USA in 1929 [2] but is now known to have a worldwide distribution and is endemic in many areas of Africa [3], Australia [4], North America [5], South America [6,7] and Asia [8,9]. For a number of decades, Vaccinia virus (VACV) was the etiological agent of a similar disease in domestic pigs with distinctive pustular lesions [10].…”