Immune Responses to Influenza Virus and Its Correlation to Age and Inherited Factors

Abstract

Influenza viruses belong to the family Orthomyxoviridae of enveloped viruses and are an important cause of respiratory infections worldwide. The influenza virus is able to infect a wide variety species as diverse as poultry, marine, pigs, horses, and humans. Upon infection with influenza virus the innate immunity plays a critical role in efficient and rapid control of viral infections as well as in adaptive immunity initiation. The humoral immune system produces antibodies against different influenza antigens, of which the HA-specific antibody is the most important for neutralization of the virus and thus prevention of illness. Cell mediated immunity including CD4+ helper T cells and CD8+ cytotoxic T cells are the other arms of adaptive immunity induced upon influenza virus infection. The complex inherited factors and age related changes are associated with the host immune responses. Here, we review the different components of immune responses against influenza virus. Additionally, the correlation of the immune response to age and inherited factors has been discussed. These determinations lead to a better understanding of the limitations of immune responses for developing improved vaccines to control influenza virus infection.

Glutathione increase by the n‐butanoyl glutathione derivative (GSH‐C4) inhibits viral replication and induces a predominant Th1 immune profile in old mice infected with influenza virus

“…Several factors influence the outcome of the infection among which the interplay between virus and host cell response plays a major role. The risk of influenza‐associated death is higher among elderly (persons aged >65 years) …”

“…The aged immune system is characterized by an imbalance in the Th1/Th2 response and the lack of an efficient Th1 response puts the elderly at risk to exacerbation of the disease state …”

“…The risk of influenza-associated death is higher among elderly (persons aged >65 years). 1 The aged immune system is characterized by an imbalance in the Th1/Th2 response and the lack of an efficient Th1 response puts the elderly at risk to exacerbation of the disease state. 1 The aging process is accompanied by complex age-related changes that affect the cell redox homeostasis, the immunity and the host defenses against viral infections.…”

“…1 The aged immune system is characterized by an imbalance in the Th1/Th2 response and the lack of an efficient Th1 response puts the elderly at risk to exacerbation of the disease state. 1 The aging process is accompanied by complex age-related changes that affect the cell redox homeostasis, the immunity and the host defenses against viral infections. In particular, old individuals are characterized by chronic oxidative stress and low-grade inflammation, referred to as "inflamm-aging," responsible for a blunted immune response, thus increasing the susceptibility of this population to infections and predisposing them to a reduced response to vaccination.…”

Influenza vaccine response: future perspectives

“…Additionally, a decline in immune response in the innate and adaptive immune system in the elderly leads to greater susceptibility to infection and lower responsiveness to the vaccine. Critical characteristics of immunosenescence include, for example, decreased number and function of dendritic cells, an alteration in the number of natural killer cells, and a decreased number of naive T and B cells [6,17,18]. The major factors known to determine influenza vaccine response are summarized in Table 2.…”