Enterovirus 71 B5 subgenotype (EV-A71B5) is a primary human pathogen of hand, foot, and mouth disease. In this study, we aimed to prepare a novel recombinant protein polyprotein (P1) and 3D polymerase (3Dp°l) protein of EV-A71B5 and determine mice immunogenicity and neutralization activity against EV-A71 of the B5 subgenotype commonly found in Thailand. Using a dual promoter system and investigating its expression in Sf9 cells, we constructed a novel recombinant protein containing P1 and 3Dp°l protein. The purified P1-3Dp°l was observed by western blotting and transmission electron microscopy (TEM) to determine the particle size. Furthermore, we determined the immunogenicity and neutralization activity against EV-A71 of the B5 subgenotype using concatenation of Bagg and Albino (BALB/c) mice. The results revealed that P1-3Dp°l was expressed in Sf9 cells. We used TEM to visualize the particle size of P1-3Dp°l to be approximately 33 nm. P1-3Dp°l had the potential to elicit the production of immunoglobulin G and immunoglobulin M antibodies and the T helper type 1-dominant cytokine interferon-γ after immunizing BALB/c mice and inducing neutralization antibodies against EV-A71B5. Our results demonstrated that Sf9 cells successfully produced P1-3Dp°l, which can leverage immune efficacy in BALB/c mice and be used to develop vaccines against the EV-A71B5 strain prevalent in Thailand.
Key words: Enterovirus 71 subgenotype B5, polyprotein, 3D polymerase protein, transmission electron microscopy, T helper type 1-dominant cytokine interferon-γ
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