ABSTRACT
The emerging new COVID 2019 pandemic, which started in 2019 in China (Wuhan) and is caused by SARS-CoV-2, raises critical concerns due to high morbidity and mortality. As many patients are infected and the numbers still increase, this may suggest that there are different variants of the virus and some of them are more pathogenic. Besides, the virus is suspected to have various evolutionary pathways since SARS-CoV-2 belongs to the RNA viruses' family, which is characterized by a high mutation rate. Additionally, it is crucial to understand the life cycle of the virus to be able to urge antiviral studies. Genotyping studies about viruses are also important in order to understand the transmission and evolution of the virus. The genome of SARS-CoV-2 has a furin-like cleavage site in its S protein that may affect its pathogenicity. It was found that insertions and deletions in S protein have an impact on the transmission and fusion of the virus. The single nucleotide polymorphisms (SNP) genotypes are used to track the relationship of virus isolates. Se-quence alignment revealed the presence of hundreds of inter-host mutations during person-to-per-son transmission. Furthermore, genetic recombination provided a second mechanism for virus evo-lution. In this review, we highlight the life cycle of the virus and methods of virus evolution caused by mutations or recombination of viral genomes.Copyright © 2021 Bentham Science Publishers.
ABSTRACT
Background:Influenza is an important respiratory infection, causing 250,000 to 500,000 deaths annually. Influenza virus A is the most virulent and associated with winter epidemics in temperate regions, more persistent transmission in the tropics, and occasional large-scale global pandemics. But, there is variability in the pattern, and the H1N1 pandemic of 2009-2010 was unusually with a large spike in spring and a sharp decline continuing throughout winter. Varying in pattern is due to antigenic shift and drift and reassortment of the virus. Methods:A prospective study was carried out in Advance Basic Sciences & Clinical Research Lab, Department of Micro- biology in SMS Medical College & Hospital, Jaipur for diagnosis of Influenza A virus as well as subtyping was done using RT-PCR technique over 1 year period (July 2019 to June 2020) and demographic data was noted. Results:Total of 7213 samples were tested, out of which 498 (6.90%) were positive for Influenza A which is less from the previous year’s 22.46%. Out of total positive cases Influenza a (H1N1) pdm09 was 24.9% and InfA H3N2 was 75.10%. InfA H3N2 was the prominent circulating strain in all months while Influenza a (H1N1) pdm09 was prominent strain pre- vious year. Majority of positive cases were found in March 2020 (43.17%), September 2019 (28.51%). Most of these cases 36.14% were from age group between 20 to 40 years. Conclusions: A decline in the positivity of influenza infection compared to last year is seen which could be in part due to circulation of SARS COV 2 and measures of prevention undertaken by community to prevent it. Demographic parame- ters and seasonal variation of Influenza A virus give ideas to create awareness and to improve control strategies to mini- mize the morbidity, mortality and spread of disease.