Efficacy of amitraz plus inactivated parapoxvirus ovis in the treatment of canine generalised demodicosis.

Canine generalised demodicosis (CGD) is a challenging disease to treat effectively. Inactivated parapoxvirus ovis (iPPVO) could help to accelerate treatment with acaricidial therapy by altering the immune response. This study was designed to investigate the effects of treating CGD with amitraz plus iPPVO in terms of clinical outcomes and blood parameters. The study involved 16 dogs ranging in age from eight months to six years and weighing between 10 and 40 kg. Eight dogs were treated with amitraz and eight with amitraz plus iPPVO. Biochemical analysis of whole blood and serum, including serum C reactive protein (CRP) and serum amyloid A (SAA), was performed. Skin scrapings were conducted on days 0, 10, 40, 80 and 120 of treatment, and mite numbers were recorded. Clinical remission was determined according to mite numbers and clinical scores. The difference in mean whole remission days between the amitraz group (104.3 days) and the amitraz+iPPVO group (84.5 days) was statistically significant (P<0.05). Mean clinical scores were also significantly better in the amitraz+iPPVO (5.60) group when compared with the amitraz group (7.65). No adverse reactions were observed in either group. In view of these findings, the use of iPPVO in conjunction with amitraz can be recommended for treating CGD.

Inactivated parapoxvirus ovis activates canine blood phagocytes and T lymphocytes.

Inactivated parapoxvirus ovis (iPPVO) shows strong immunomodulatory activities in several species and is used in veterinary medicine as an immunostimulatory biological for the prevention and/or treatment of infectious diseases. In this study the immunostimulatory capacity of iPPVO on the innate immune system was investigated in vitro by the evaluation of induction of the oxidative burst and modulation of phagocytosis by canine blood leukocytes (polymorphonuclear cells and monocytes) of dogs. In addition, the activation of canine T lymphocytes was also studied. After stimulation with iPPVO the phagocytosis of FITC-labeled Listeria monocytogenes was increased in canine blood monocytes and neutrophils. Enhanced burst rates by canine monocytes stimulated with iPPVO were observed and the MHC-II expression on canine CD14+ monocytes was elevated following stimulation with iPPVO compared to the stabiliser control. Canine CD4+ T cells were activated for oligoclonal proliferation in response to iPPVO. This study shows that iPPVO is able to stimulate both phagocytotic and T-cell-dependent immune mechanisms in canine blood leukocytes.

In vitro susceptibility of sea lion poxvirus to cidofovir.

Parapoxviruses of seals and sea lions are commonly encountered pathogens with zoonotic potential. The antiviral activity of the antiviral compounds isatin-beta-thiosemicarbazone, rifampicin, acyclovir, cidofovir and phosphonoacetic acid against a parapoxvirus (SLPV-1) isolated from a Californian sea lions (Zalophus californianus) was evaluated. Cidofovir was able to reduce virus-induced cytopathic effect of SLPV-1 in confluent monolayers when used in concentrations greater than 2microg/ml. A decreasing virus yield was observed in the presence of increasing concentrations of cidofovir, which confirmed the ability of cidofovir to inhibit SLPV-1 replication. The in vitro efficacy of cidofovir against SLPV-1 indicates the therapeutic potential of cidofovir for the treatment of infections of humans and pinnipeds with parapoxviruses of seals and sea lions. This study confirms the previously proposed therapeutic potential of cidofovir for the treatment of parapoxvirus infections.

Parapoxvirus causes a deleterious disease in red squirrels associated with UK population declines.

The disease implications of novel pathogens need to be considered when investigating the ecological impact of species translocations on native fauna. Traditional explanations based on competition or predation may often not be the whole story. Evidence suggests that an emerging infectious disease, caused by a parapoxvirus, may be a significant component of the impact that the introduced grey squirrel has had on UK red squirrel populations. Here we validate the potential role of parapoxvirus by proving that the virus is highly pathogenic in the red squirrel while having no detectable effect on grey squirrel health.

Parapoxviruses are strongly inhibited in vitro by cidofovir.

Three parapoxviruses which cause orf or related diseases in humans and animals and the orthopoxvirus, vaccinia virus, were tested for their in vitro sensitivity to cidofovir. The 50% inhibitory concentration for the three parapoxviruses was between 0.21 and 0.27 microg/ml and for vaccinia was 1.32 microg/ml. The selectivity index varied from 198 to 264 for the parapoxviruses and was 42 for vaccinia virus. Virus yield assays confirmed the ability of cidofovir to reduce ortho- and parapoxvirus replication. The efficacy of cidofovir against parapoxviruses justifies its evaluation as a candidate drug for the treatment of parapoxvirus infections in humans and animals.