Background:
Flavobacterium columnare, a Gram negative bacterium, is the etiological agent of columnaris disease in fish. The disease has high prevalence and the pathogen can infect a wide-range of freshwater fish species during rapid fluctuation in environmental temperatures. Notably, during severe infection, the outbreak of disease can be resulted in mass mortality (100%), in stocked fish population. Columnaris outbreaks are more severe during spring and autumn, and are associated with stressful conditions like rapid fluctuation of temperatures, elevated organic loads, high stocking density and excessive handling. F. columnare causes acute to chronic infections and affects external organs like gills, skin, and fins; in particular, dorsal fin and surrounding skin are often exaggerated, causing “saddleback” lesions. When the disease is acute or subacute, yellowish areas of necrotic tissue can be seen in the gills, resulting in severe gill pathology. The infection may show slow to fast progression and during acute infection mortality is observed without any gross symptoms. During the last decade, frequent incidences of F. columnare outbreaks have been reported worldwide. At present no adequate prophylaxis including vaccines are available forF. Columnare in India, leaving antibiotics as the only course of action to control the disease outbreaks. Hence there is an urgent need to have an economically and practically viable vaccine against this pathogen. Further, effective vaccine delivery in fish is very challenging. Against this background, ICAR-CIFE has developed a vaccination protocol using inactivated pathogen administered through immersion method which facilitates vaccine absorption from all mucosal surfaces. The method has advantages over feed-based as well as parenteralvaccination, and the method is less stressful.:
Technology Details:
Columnaris disease is a major disease in fishoften results in mass mortality, especially during environmental stress and is caused is by Flavobacterium columnare, a Gram negative bacterium. The innovation addresses to develop an effective prophylactic method for the control of the diseases. The prophylactic measure is an inactivated vaccine against F. columnare for use in fish. This is a whole cell vaccine containing formalin-inactivated, fieldisolated F. columnare that induces specific immunity in Labeo rohita fingerlings and leading to protection against the infection. Two doses of vaccine: a primary vaccination at day zero, followed by booster vaccination at 21 days, for 1 h through immersion mode. Vaccine provides 80% of relative percent survival in Indian major carps, at optimum condition of fish rearing. Besides high level of protection, the major advantage of this innovation is that it offers a stress-free vaccine delivery in fish. An innovative method of vaccine delivery through immersion route has been developed for efficient uptake of vaccine without giving stress to fish. This is the first package of technology for vaccination in Indian major carps, which is available for field demonstration. The technology is a package of “Bacterial strain, protocol of vaccination method, information on the concentration of vaccine, and vaccine dose and duration. Additional information: Successful trials of the vaccination have been carried in selected fish farms in Maharashtra and promising results have been recorded