Background Biology

Innate and Adaptive Immunity 

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The immune system takes two different, yet interdependent approaches to defeating a foreign pathogen such as a bacteria or a virus.

The innate immune system. This system mounts an immediate response to an infection without being specific to the pathogen in question. The innate immune system is the more primitive of the body’s responses to infection. It is made up of immune cells and receptors (including so-called “toll-like receptors” or TLRs) that immediately recognize certain molecular patterns uniquely associated with pathogens and then launch a first-line attack on the invaders. Because it recognizes only general molecular patterns on the surface of pathogens, and because some pathogens develop ways to evade its defenses, the innate immune system may have limited capability in holding back some infections.

The adaptive immune system. This system has the distinct advantage of highly specific recognition of virtually any pathogen the body might encounter, as well as providing immunological memory of infection. It is responsible for the production of antibodies and killer T cells. However, the adaptive system relies upon the innate systems recognition of a pathogen to initiate its own response to a pathogen. While the adaptive systems recognition of a pathogen is extremely precise, it is relatively slow compared to the timescale of an infection.

Together, these two systems provide a comprehensive immune response to infectious agents. It is precisely this biological partnership that has been harnessed to produce VaxInnate’s highly specific and potent vaccines.

Hemagglutinin and Antigenic Variation  

Hemagglutinin binds to sugars on the surface of host cells and helps the virus to fuse with, and enter the cell. Its essential role in the infection cycle has made HA an obvious and effective target (antigen) for traditional influenza vaccines. Another viral antigen, neuraminidase (NA), clips the sugars, preparing the virus to freely exit the cell, and continue the replication cycle by infecting other cells. There is considerable genetic variance among type A virus strains, and the variants are grouped according to the particular HA and NA sub-types present. Influenza A subtypes have designations such as H3N2 or H1N1, reflecting the identity of the particular HA and NA proteins variants expressed by the virus subtype. Most human influenza viruses have H1 or H3 hemagglutinins, while avian influenza viral strains characteristically have H5, H7 or H9.