ABSTRACT
Japanese encephalitis (JE) is a mosquito borne flaviviral zoonoses, causing fatal disease in equines and humans. JE is endemic in most of the states of India with occurrence of human cases every year. The horses are not vaccinated against JE in India and thus they are at more risk of acquiring the disease. Due to nonavailability of indigenously developed ELISA and high cost of imported kits, regular sero-surveillance is not being carried out to assess the true picture of JE virus in equine population of India. Therefore, a recombinant NS1 protein based indirect IgG ELISA was developed with the objective to assess the sero-positivity of JE virus in equine population of India. The diagnostic sensitivity and specificity of developed ELISA was 84.73% and 86.70%, respectively. The validation studies revealed good reproducibility of ELISA with kappa value ranging from 0.75 to 1 between the results of different laboratories. A total of 2,069 horse serum samples were screened using the developed ELISA and 401 samples were positive for IgG against JEV with an overall sero-positivity of 19.38% in equine population of India. A sero-positivity of 25.90% and 12.22% was recorded in Himachal Pradesh and Jammu-Kashmir, both hill states of North zone of India for the first time, revealing the spread of virus to the nonendemic parts of the country. The high sero-positivity of JE virus recorded in equine population warrants the need for initiation of vaccination of horses in India to prevent the morbidity and mortality.
