Virus genetic variations and evade from immune system, the present influenza challenges: review article

The spread of influenza viruses in multiple bird and mammalian species is a worldwide serious threat to human and animal population's health and raise major concern for ongoing pandemic in humans. Direct transmission of the avian viruses which have sialic acid specific receptors similar to human influenza viruses are a warning to the emergence of a new mutant strain that is likely to share molecular determinants to facilitate their replication in human host. So the emerge virus can be transmitted easily through person to person. The genetic variations of the influenza viruses, emerge and re-emerge of new antigenic variants, and transmission of avian influenza viruses to human may raise wide threat to public health and control of pandemic influenza. Vaccination, chemoprophylaxis with specific antiviral drugs, and personal protective non-pharmacological measures are tools to treat influenza virus infection. The emergence of drug resistant strains of influenza viruses under drug selective pressure and their limited efficacy in severe cases of influenza infections highlight the need to development of new therapies with alternative modes. In recent years several studies have been progressed to introduce components to be act at different stages of the viral life cycle with broad spectrum reactivity against mammalian and bird influenza subtypes. A wide variety of different antiviral strategies include inhibition of virus entry, blocking of viral replication or targeting of cellular signaling pathways have been explored. The current inactivated influenza vaccines are eliciting only B-cell responses. Application of the vaccines has been limited due to the emergence of the new virus antigenic variants. In recent decade development of gene vaccines by targeting various influenza virus proteins have been interested because significant potential for induction of both humoral and cell mediated immunity responses. Enhanced and directed immune responses to viral vaccine can be achieved by using adjuvant. The ability of biological molecular adjuvant such as cytokines, interlukines, and bacterial derivatives to improve the immunogenicity of vaccines as a novel strategy is under evaluation, however, and immune system regulator proteins have additional considerations.