Virology

Biography

Biography: Isabel Yee Pinn Tsin

Abstract

The hand, foot and mouth disease is caused by a group of Enteroviruses such as Enterovirus 71 (EV-A71) and Coxsackieviruses. Mild symptoms of EV-A71 infection in children range from high fever, vomiting, rashes and ulcers in mouth. EV-A71 can produce more severe symptoms such as brainstem encephalitis, leading to cardiopulmonary failure and death. The lack of approved vaccines against EV-A71 highlights the urgency of developing preventive agents against EV-A71 to prevent further fatalities. The molecular basis of virulence in EV-A71 is still uncertain. In this study, the EV-A71 virus (5865/Sin/000009) was genetically modified by substituting nucleotides at positions 2735, 2875, 3167, 3173, 6129 and creating a partial deletion (PD, ∆11bp) of the 5’-NTR region. Amongst the 6 mutants, mutants 2735, 3167 and 3173 were constructed through codon-deoptimsation. The virulence of the mutated EV-A71 strains were evaluated in Rhabdomyosarcoma cell culture by tissue culture infectious dose (TCID₅₀) determinations and real time Reverse-Transcriptase Polymerase Chain Reaction (RT-PCR). Mutants 2735 and 3173 had minimal cytopathic effects when compared to mutants 2875, 3167, 6129 and PD when transfected into RD cells. This was consistent with the RT-PCR results that showed the viral RNA copy number for mutants 2735, 3173 and 6129 to be of lowest amount. Analysis of the TCID₅₀ values indicates that mutants 2735 and 3173 were attenuated five-fold as compared to the wild type. Hence, the nucleotides at C2735 and C3173 maybe potential molecular determinants in EV-A71 and should be subject to further evaluations by other tests in vitro and in vivo