Genetic characterization of Chikungunya virus 2009 isolates from South India

Area of Science:

• Virology
• Genetics
• Molecular Biology

Background:

• Chikungunya Virus (CHIKV) re-emergence has led to significant outbreaks with severe multi-organ clinical manifestations.
• Recurring outbreaks in India highlight the need to study CHIKV genetic diversity.

Purpose of the Study:

• To investigate the genetic diversity of CHIKV strains responsible for the 2009 outbreak in Southern India.
• To identify genetic mutations and their structural implications in circulating CHIKV isolates.

Main Methods:

• Blood samples were collected from suspected CHIKV cases in Tamil Nadu and Kerala during the 2009 outbreak.
• Partial E2 gene segments were amplified using Reverse Transcription Polymerase Chain Reaction (RT-PCR).
• Phylogenetic and mutational analyses were performed on positive CHIKV samples.

Main Results:

• Out of 119 samples, 37 tested positive for CHIKV by RT-PCR.
• Phylogenetic analysis confirmed isolates belonged to the Indian Ocean Lineage (IOL) of the ECSA genotype.
• Mutational analysis identified substitutions including a novel V386G mutation in all sequences, with unique W339R and S375P substitutions in two isolates.

Conclusions:

• The 2009 CHIKV outbreak in Southern India was caused by strains of the Indian Ocean Lineage (ECSA genotype).
• Identified mutations, including a novel V386G, likely contribute to structural changes and altered intraprotein interactions.
• Further research into these mutations' impact on CHIKV pathogenesis and transmission is warranted.