Molecular epidemiology of Japanese encephalitis virus in pig population of Odisha, Assam and Manipur states of India

Abstract

Japanese encephalitis virus (JEV) comes under the family Flaviviridae and genus flavivirus.It predominantly infects the children under the age of 10 years and the case fatality rate can stretch out as high as 30%. Pigs act as reservoir and amplifying intermediate host for JEV.Recent report suggested longer persistence of JEV in tonsil than in circulation of experimentally infected pigs. The current investigation was conducted to understand the prevalence and molecular epidemiology of JEV infection in pigs in three different geographical sites in India (Odisha, Assam and Manipur). Serum samples were tested by ELISA and RT-PCR for detection of JEV, while only RT-PCR was done in case of tonsils tissues collected from pigs slaughtered in abattoir. Prevalence of JEV was highest in Manipur (25.45% in serum and 10.08% in tonsil) but lower in Assam (3.75% in serum and 0% in tonsils) and Odisha (1.49% in serum and 3.7% in tonsils). The percentage of sero-positivity was found to be 3.75% of IgM and 9.9% of IgG in Assam and Odisha respectively. Genotype III (GIII) of JEV was the dominant genotype and sporadic mutations of S83G, H76P, E78Q, C55S, and S64W along with two consistent mutations V46S and V51I were observed in all the GIII strains. Analysis of the E gene sequence revealed a single mutation, S118N in the GI strain. Older pigs (above 7 months) were found to be infected relatively more (8.6%) than younger pigs (age group 3-7 months). In conclusion, the high JE virus infection rate of pig in the current locations suggests the need for continuous surveillance of this virus in pigs which will ultimately help to adopt an effective control strategy to prevent the spread of JE infection to human..

Epidemiological study of Acute Encephalitis Syndrome and Japanese Encephalitis burden in Sivasagar district of Assam, India

“…20 In peninsular and eastern parts of India, pigs are the main vertebrate host of JEV and the major reservoir of JE infection . 21 Infected pigs act as amplifying hosts. Therefore, pig rearing is an important risk factor of JE transmission in humans.…”

Japanese encephalitis virus in India: An update on virus genotypes

“…Among the States studied, the highest prevalence of JEV was detected in Manipur (25.45% in serum and 10.08% in tonsils) than in Assam (3.75% in serum and 0% in tonsils) and Odisha (1.49% in serum and 3.7% in tonsils). The study evidently showed that although JEV GIII was found to be dominant in the circulation, the detection of GI in Odisha during 2019 again indicated the ongoing strain shifting the phenomenon of the existing GIII to GI in JE endemic areas, such as Odisha 55 . The change in the geographical distribution of the JEV clade has been recently visualized by isolating the JEV GIII (IVRI395A-a neurovirulent strain) from pigs with reproductive failure in Uttar Pradesh, India.…”

Japanese Encephalitis Virus Genotype III Strains Detection and Genome Sequencing from Indian Pig and Mosquito Vector

“…The incidence of Japanese encephalitis in recent times has shown an increasing trend in India and has become a major public health problem [ 2 , 7 ]. Assam is the north-eastern (NE) state of India and has the largest pig population in the country with abundance of rainfall and rice cultivated land, making Assam the most vulnerable state for JE incidences [ 2 , 8 , 9 ]. In Assam, JEV was first reported in the year 1976 from Lakhimpur district and since then incidences of JE have markedly increased [ 10 , 11 ].…”