Pathogenic and Genotypic Characterization of a Japanese Encephalitis Virus Isolate Associated with Reproductive Failure in an Indian Pig Herd

• Published in: PloS one 2016-02, Vol.11 (2), p.e0147611-e0147611
• Main Authors: Desingu, P A, Ray, Pradeep K, Patel, B H M, Singh, R, Singh, R K, Saikumar, G
• Format: Article
• Language: English
• Subjects: Analysis; Animals; Aquatic insects; Biology and Life Sciences; Blurring; Brain; Causes of; Cell Line; Cercopithecus aethiops; Chemical properties; Cloning; Committees; Development and progression; Disease transmission; Diseases and pests; Encephalitis; Encephalitis Virus, Japanese - classification; Encephalitis Virus, Japanese - genetics; Encephalitis Virus, Japanese - isolation & purification; Encephalitis, Japanese - veterinary; Failure; Flaviviruses; Gene sequencing; Genetic aspects; Genetic relationship; Genotype; Genotype & phenotype; Genotypes; Hogs; Infections; Japanese encephalitis; Lesions; Livestock; Medicine and Health Sciences; Mice; Mosquitoes; Neurovirulence; Outbreaks; Pathology; People and Places; Phylogeny; Physiological aspects; Reproduction; Reproductive failure; Research and Analysis Methods; Selection, Genetic; Serological surveys; Spatial distribution; Stillbirth; Studies; Suidae; Swine; Swine Diseases - physiopathology; Swine Diseases - virology; Vector-borne diseases; Vero Cells; Viral envelope proteins; Viral infections; Viral Proteins - genetics; Virulence (Microbiology); Viruses; Zoonoses
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0147611

India is endemic to Japanese encephalitis virus (JEV) and recurrent outbreaks occur mainly in rice growing areas. Pigs are considered to be the amplifying host for JEV and infection in gestating pigs results in reproductive failure. Most studies conducted on JEV infection in Indian pigs have been serological surveys and very little is known about JEV genotypes circulating in pigs. So the potential risk posed by pigs in JEV transmission and the genetic relationship between viruses circulating in pigs, mosquitoes and humans is poorly understood. This study was conducted in pigs with a history of reproductive failure characterized by stillborn piglets with neuropathological lesions. Japanese encephalitis (JE) suspected brain specimens inoculated intracerebrally into mice and Vero cells resulted in successful isolation of JEV/SW/IVRI/395A/2014. Clinicopathological observations in infected mice, demonstration of JEV antigen in brain, and analysis of the envelope protein identified the swine isolate as being neurovirulent. Phylogenetic analysis based on prM and E gene sequences showed that it belonged to genotype III. This swine isolate was closely related to JEV associated with the 2005 outbreak in India and JaoArS982 from Japan. Phylogenetic analysis of JEV strains collected between 1956 and 2014 in India categorized the GIII viruses into different clades blurring their spatial distribution, which has been discernible in the previous century. Isolation of JEV from stillborn piglets and its close genetic relationship with viruses detected at least three decades ago in humans and mosquitoes in Japan suggests that the virus may have been circulating among Indian pigs for several decades. The close similarity between the present swine isolate and those detected in humans affected in the 2005 outbreak in Uttar Pradesh, India, suggests the need for more intensive surveillance of pigs and implementation of suitable strategies to control JE in India.