Influenza virus: Genomic insights, evolution, and its clinical presentation.

Influenza viruses belong to the family Orthomyxoviridae and have been a concern for public health due to frequent epidemics and sporadic waves of pandemics. According to WHO, seasonal strains of the influenza A virus (IAV) infect 3 to 5 million people every year and result in 0.29-0.65 million deaths globally. Among all proteins of IAV, the hemagglutinin (HA) and neuraminidase (NA) have high mutation rates and have been reported to undergo antigenic drift and shift leading to novel strains. Hence continuous revision in drugs and vaccines regime is an economic burden as these reassortments can cause high morbidity among the immunologically naive population. Infection rates are higher among older age groups, infants and patients reported with other respiratory distress. Routine diagnostic tests include reverse transcription polymerase chain reaction (RT-PCR), viral culture, and immunofluorescence assays; however, the diagnosis may be hindered due to the resemblance of the clinical presentation of other respiratory viruses with influenza viruses. Here we present a comprehensive review which sheds light on the genomic structure, evolution, pathogenicity and clinical presentation of influenza virus that can help to distinguish it from other respiratory viruses. A detailed analysis will ultimately pave the way for the development of more effective antiviral drugs and a universal vaccine.