Full genome sequence and virulence analyses of the recent equine isolate of Japanese encephalitis virus.

This research article investigates the genetic makeup and virulence of Japanese encephalitis virus (JEV) found in an affected horse in Japan, comparing it to the common strain of the virus. The study suggests continued vaccination efforts for horses as the strain possesses significant neurovirulence.

Full Genome Analysis of the JEV Strain

• The researchers determined the complete genetic sequence of the JEV strain, named JEV/eq/Tottori/2003, that infected a horse in Japan. This process allowed scientists to study the virus’s molecular structure and components in extensive detail.
• The analysis revealed that the horsely acquired virus’s genome bears similarity to Genotype I of JEV strains, which is the dominant type circulating in Japan currently.

Virulence Assessment

• The study also involved testing the virulence of this isolated JEV strain. Virulence signifies the virus’s capability to cause disease or harm.
• Tests were conducted on mice to determine both neurovirulence and neuroinvasiveness. Neurovirulence refers to the harmful effects a virus can have on the neural tissue, causing neurological disorder or damage. On the other hand, neuroinvasiveness represents the ability of the virus to enter the host’s nervous system.
• In this case, the JEV strain from the affected horse exhibited high neurovirulence but not neuroinvasiveness. It means that the strain is capable of causing severe neurological damage, but isn’t particularly adept at entering the nervous system.

Implications for Vaccination Programs

• The conclusions drawn from this research highlight the need for persistent vaccination efforts of horses against JEV.
• Even though the isolated strain demonstrated more similarity genetically to the currently dominant strain, its high neurovirulence indicates a continuing potential for causing serious disease.
• Hence, preventive measures, namely vaccination, remain crucial to control the spread and impact of this viral disease in animals such as horses.