Influenza A virus: Origin and its subtypes

Abstract

INTRODUCTION: It is known that flu epidemics arise quite frequently, but there are no regular intervals between these events. Epidemics may differ in their consequences, but they often cause an increase in mortality in elderly people. The great flu epidemic of the last century claimed millions of human lives. Scientist Richard E. Shope, who investigated swine flu in 1920, suspected that the cause of the illness was a virus. As early as 1933, scientists at the National Institute for Medical Research in London isolated the virus for the first time. Thus, the present study seeks to understand how the influenza A virus emerged and was identified. METHOD: Approach used this is a literature review, where research was conducted through scientific articles, published in the MEDLINE and SciELO database, where 4 were selected because they fit the inclusion method. RESULTS and DISCUSSION: The viral etiology of influenza was proven in 1933, and the three serotypes that infect humans were only identified in 1950. In that same year, it became clear that the strain responsible for the 1918-1919 episode belonged to the variety particular antigen of subtype A. In 1957, with the emergence of subtype A, influenza reached China and, in 1968, in Hong Kong, subtype A appeared, causing a moderately severe pandemic. Even after almost a century after the recognition of this strain, the flu virus remains one of the greatest health control challenges due to its easy antigenic variability and contagiousness. FINAL CONSIDERATIONS: For the formation of new subtypes, there is recombination, which corresponds to a mixture of, for example, genes from a virus that infects human beings with genes from viruses that infect other animals, such as birds, thus explaining how the retrovirus Influenza type A can become more aggressive due to mutations derived from the mixture of genes from animal viruses,  especially birds and swine.

DOI:https://doi.org/10.56238/globalhealthprespesc-019