Background:
Lactococcus garvieae is an emerging, deadly zoonotic fish pathogen, reported globally, and responsible for millions of dollars of huge economic loss in marine and freshwater aquaculture. Originally isolated in 1980s from clinical samples of bovine mastitis in United Kingdom as Streptococcus garvieae, this bacterium causes hemorrhagic septicemia and meningoencephalitis in around 60 fish species. The crop loss due to L. garvieae infection is approximately 20 to 60% of the total fish production, within few weeks of first detection of infection. Survived fish are difficult to market due to its gross appearance and also becomes asymptomatic carrier and transfer the infection to other healthy fish in the vicinity. The outbreak of disease mainly occurs during warm summer months, when the water temperature of aquaculture pond increases over 16 ºC, and so the disease caused by this bacterium is called as “Warm Water Lactococcosis” (WWL). Because of change in climate, high pathogenicity of this bacterium, development of antibiotic-resistant strains, lack of suitable diagnostic kits and lack of appropriate control measures, currently the rainbow trout farming is highly threatened by this bacterium. Due to movement of infected fish from one geographical location to other, this bacterium has spread to every continent in last few decades. Therefore, in recent year infection with L. garvieae is considered as the most important risk factors for fish farming in Asia, Europe, Africa, Middle East, United states and Australia. At present from clinical samples, L. garvieae is identified by traditional microbiology, biochemical tests, bacterial growth tests and PCR based molecular methods. These traditional methods require few days to several weeks for identification of this pathogen, and by that time the infection has abundant opportunity to spread to other organisms by horizontal transmission. Moreover, by traditional methods this bacterium is often misidentified as Streptococcus inae, Enterococcus sp. and Lactococcus lactis because of its phenotypical and biochemical similarities with L. garvieae. The clinical sign of disease caused by S. inae and L. garvieae are almost similar, so often it is difficult to distinguish between these two bacterial species. Currently, there is no simple and quick means of distinguishing between these closely related bacterial taxa. PCR based molecular methods require expensive chemicals and costly equipment apart from being time consuming. Faster, sensitive, specific, cost-effective and easy to perform detection methods are the primary tools for mitigating the transmission of WWL associated with L. garvieae. Process and kit for the faster detection of L. garvieae are therefore very essential for minimizing their transmission and lethality associated with their infection.:
Technology Details:
The present invention relates to visual detection of zoonotic bacterial pathogen, Lactococcus garvieae. More specifically, this invention relates to specific concentration and compositions of oligonucleotides, protocol and diagnostic kit for rapid, specific and cost effective detection of L. garvieae, wherein the detection of L. garvieae is carried out within 40 min by visual examination of change in color of reactant.