Evaluating Genetic Alterations by Complete Virus Sequencing Method for Takahashi Rubella Vaccinal Virus in Various Passages

Abstract Rubella is a mild-fevered viral disease appearing with a scattered spot of the maculopapular rashes. This disease is similar to the other viral diseases causing cutaneous rashes, such as measles, dengue, human herpes virus 6 or scarlet fever in terms of the clinical signs. The disease usually has no general symptoms among children or has very minor symptoms, however, for adults it causes mild fever for 1 to 5 days; restless headache, mild nasal discharge, and conjunctivitis. An important feature of the rubella virus, like other RNA viruses, is the high mutation rate resulting in antigenic variation at the level of neutralizing proteins. In this study, we investigated the rate of genetic alterations of the Takahashi rubella virus during 5 passages in human fetal lung diploid cells. Because understanding the extent of genetic variation of these viruses during consecutive passages and the number of passages for the viruses to retain their basic characteristics is essential in vaccine production to use a virus not differing further with the virus isolated from the field. For research, the virus prepared in the medical viral vaccine production unit was used and the virus neutralization method with specific antibody was used to confirm and identify the virus present in the samples and its type. Then, by inoculating the identified live virus specimens in culture, extracting the virus was initiated. Tests were performed over passages 1 and 5 of the viruses using RT-PCR and R-value test and Real-Time RT PCR and the PCR products were sent for sequencing. To compare the results of the sequencing and the R-value of the virus with each other and with the prototype of the mother virus seed, the genetic difference was studied through investigating the complete sequence of the nucleic acids of the virus using Bio Edit software and their affinity during the fifth passage with the virus of primary passage (fifth passage on the cell) was measured using the DDVNT method (Double Dimension virus Neutralization Test). Ultimately, the results were collected and analyzed using MiniTab and regression curves to evaluate the R-value and molecular and genetic software was used to compare the sequences with each other and with the sequences in the gene bank. Investigating the results of all the above tests performed on the selected passages (P0, P5,) within 5 Rubella virus passages, it was found that the Rubella Takahashi viruses were not exposed to drastic changes during successive passages leading to major changes. Moreover, they were not far from the characteristics of their original passage. Keywords: Rubella, Genome Sequencing, Identification, Antigenic Diversity, Mutation.