The present study highlights pathogenesis and molecular aspects of Coxsackie virus A-16 (CVA-16) strains isolated from hand, foot, and mouth disease (HFMD) cases from India using a neonatal mice model. ICR mice were intraperitoneally inoculated with CVA-16/311 strain isolated from HFMD cases. Mice developed hind and forelimb paralysis on day 3 of post infection. Histopathological observations of hind limb muscles showed necrosis, dissolution of muscle fiber cells, infiltration of inflammatory cells, marked dilated ventricle, hemorrhages, and neuronal degeneration in the brain. Immunohistochemical studies revealed high expression of CVA-16/311-specific viral antigen in limb muscles, brain, heart from day 3 till day 7 of post-infection. VP1 gene-based reverse transcription polymerase chain reaction conducted in RNA samples of different tissue organs of infected mice followed by sequencing of the positive amplimers revealed presence of CVA-16/311-specific viral sequences. Phylogenetic analysis based on the VP1 gene showed the presence of B1c sub genotype of CVA-16/311 strain in targeted tissue organs. Sequence analysis revealed major genetic changes in heart, skeletal muscle tissues at the nucleotide and amino acid levels. Genetic changes occurred in organs of mice might predict some potential targets and might act as markers of virulence for neuronal tropism. Pathogenesis and molecular studies of CVA-16 strains isolated from HFMD cases using neonatal mice model was conducted for the first time from India.
Keywords: CVA-16/311; Coxsackie virus A-16; HFMD; IHC; histopathology; reverse transcription PCR.
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