National Research Development Corporation (NRDC has developed a tissue culture sheep pox vaccine. The technology was developed by one of NRDC Associated R&D Institute and is now available for commercial exploitation.
The live attenuated freeze dried vaccine prepared from Romanian strain of sheep pox virus confers immunity in all types of sheep against sheep pox. The vaccine evokes thermal and local cutaneous reaction following vaccination but without generalization in susceptible sheep, stated N G Lakshminarayan, manager, NRDC, Regional Office, Bangalore.
The virus is grown in primary monolayer cultures namely lamb testicular cell culture in Roux flasks. The sterile virus contents, harvested by two cycles of freezing and thawing six to seven days of post-infection where CPE is observed in more than 80 per cent cells. The cellular debris or cell aggregates are removed by filtration. Equal quantity of preservative comprising 5 per cent LAH and 10 per cent sucrose or any other suitable stabilizer is added before freeze drying.
The standardization of vaccine has been achieved after a series of identification process to assess the moisture content. Several tests like sterility virus titration, safety and potency have been carried out.
The Corporation has recommended a dose as 0.1 ml. for all age groups, and is given intradermally in the caudal fold. It can also be inoculated on the tip of the ear.
The vaccination is expected to give lasting immunity for one year. It can be used for prophylactic vaccination and in the face of the outbreak in free flocks only, stated Lakshminarayan.
The vaccine should be stored in a refrigerator/deep freeze. The keeping quality of the vaccine has been found to be six months at two degree to four degree Celsius. Vaccine should be transported on ice in thermos box/thermocol container, stated Lakshminarayan.
It is recommended that sheep in the enzootic area should be regularly vaccinated every year. Data should be collected with regard to the breakdown of immunity and its cause investigated. In few cases, where the local reaction progress to ulceration, application of boroglycerine will alleviate the condition. Lambs/Sheep not showing 'take' following inoculation should be revaccinated if it is a primary inoculation.
According to NRDC, it recommends that the vaccine can be made available at Rs 60 for 100 doses.
Karnataka Veterinary, Animal and Fisheries Sciences University, Nandinagar, had already developed the sheep vaccine which is used in government veterinary centres. The initiative for the vaccine development is mostly confined to veterinary institutes of the state government
Although the incidence of sheep pox is on the decline, there are cases of the disease which manifests as skin lesions. It is referred to as an acute to chronic disease. The severity of disease varies with age of the animal.