Susceptibility of various cell lines to the Chikungunya virus and method selection for commercial-scale production of viral material

An increase in cases of chikungunya fever is reported in the Caribbean, Central and South America, and Southeast Asia. As there is no specific treatment for this disease and the only available treatment is symptomatic, it is very relevant to develop vaccines against chikungunya fever. To develop an inactivated whole-virion vaccine against the disease, it is important to choose a susceptible cell culture that both provides high virus yields and is used for vaccine production.

The aim of the study was to evaluate the susceptibility of multiple cell lines to Chikungunya virus infection and to select the monolayer culture method with the highest virus accumulation and yield.

Materials and methods. The study used the CHIKV_Nic strain of the Chikungunya virus and cell lines C6/36 (for virus titration), CEF, MRC-5, Vero, and 4647. While choosing the culture method, the authors used culture flasks, a cell factory, and roller bottles. The authors determined the susceptibility of the cell lines to viral infection by the degree of accumulation of the infectious agent in the culture fluid. The results of virus titration were calculated on day 5 on the basis of a pronounced viral cytopathic effect.

Results. The Vero and 4647 cell lines demonstrated the highest susceptibility to infection and virus concentrations in the culture fluid. The СEF and MRC-5 cell lines accumulated the virus at lower concentrations. The maximum virus titres (7.10–7.75 log₁₀ TCID₅₀/mL) were observed in the culture fluid 48 h after infection. The optimal multiplicity of infection (MOI) ranged between 0.001 and 0.0001 MOI/cell. At 0.0001 MOI/cell, the virus accumulated in the Vero cells cultured in roller bottles on day 2, with the maximum virus titre being 8.6±0.2 log₁₀ TCID₅₀/mL.

Conclusions. Vero cells meet the safety and stability requirements set for the production of chikungunya vaccines. The study determined the minimum MOI of the Chikungunya virus for cell culture. The roller bottle culture method provides the highest cell culture yield and the highest titre of the virus in the culture fluid.

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