Influenza viruses are the most common viral cause of respiratory illness. Millions of doses are generated annually against susceptible viral pathogens using chicken eggs. Of the many substrates, embryonated chicken eggs (ECE) have proven to be the most efficient platform for the development of many virus vaccines. Attributable mainly to the obligate intracellular nature of viruses and their successful propagation in cell lines, these cell cultures offer adequate vaccine production platforms. Cell cultures form an essential component of any vaccine production process especially in case of viral vaccines. After attaining the regulatory approvals, these vaccines are now in industrial-scale production. Ī number of types of vaccines, including live attenuated, inactivated, sub unit and conjugate vaccines, have proved their effectiveness against various pathogenic agents. The reliable and continuous availability of the vaccine production platform is, hence, a major concern for the biopharmaceutical industry. All the vaccines are dependent upon in vivo processing during a certain phase of production cycle. Moreover, necessary formulation and manufacturing requirements should be fulfilled that ensure the production of safe vaccine with high production turnover. An ideal vaccine should be adequately potent and capable of evoking a preventive immune response. Vaccines, like other biopharmaceuticals, are produced in living systems. Based on the tests, it can be concluded that chicken embryo primary cell culture addresses these issues and can serve as a potential alternative for influenza virus vaccine production. Some of the prerequisites of inactivated influenza virus vaccine production include generation of higher vial titer, independence from exogenous sources, and decrease in the production time lines. Though the viral output from the ECE was equivalent to the chicken cell culture, the time period for achieving it was decreased to half. HA, TCID 50, and CPE exhibited that these cell systems were permissive to viral infection, yielding 2–10 times higher viral titer as compared to mammalian cell lines. The primary cell culture developed from chicken embryos showed stable growth characteristics with no contamination. In-vitro substrate susceptibility and viral infection characteristics were evaluated by performing hemagglutination assay (HA), 50 % tissue culture infectious dose (TCID 50) and monitoring of cytopathic effects (CPE) caused by the virus. A comparison was made between these systems by utilizing various cell culture-based assays. The viral propagation was determined on avian origin primary cell cultures, transformed mammalian cell lines, and in ECE. Based on the fact that the avian influenza virus would infect the cells derived from its natural host, the viral growth characteristics were studied on chicken embryo-derived primary cell cultures. Transformed cell lines have attained regulatory approvals for vaccine production. Long production time, coupled with decreased supply of embryonated chicken eggs (ECE), significantly affects the conventional vaccine production. The global availability of a therapeutically effective influenza virus vaccine during a pandemic remains a major challenge for the biopharmaceutical industry.
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