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Title: Antiviral immunity and virus vaccines

Author
item BARRATT-BOYES, SIMON - University Of Pittsburgh
item Golde, William

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 4/15/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: As obligate intracellular organisms, viruses have co-evolved with their respective host species, which in turn have evolved diverse and sophisticated capabilities to protect themselves against viral infections and their associated diseases. Viruses have also evolved a remarkable variety of strategies to avoid or subvert these host defences. Antiviral immunity in higher animals is complex, and reflects a combination of innate and acquired (adaptive) immune response mechanisms, although there is considerable interplay between these two broad categories. The primary defence against viral infection in higher animals is the physical barriers for viral entry. The skin is the largest of these, protecting against viral access to the interior. Mucosal surfaces efficiently block or remove viral incursions with the enzyme rich upper gastrointestinal tract and low pH environment of the lower gastrointestinal tract. The respiratory tract has evolved physical protection as well, with the ciliated epithelium sweeping virus out of the internal space. These are physical barriers and will not be considered further. The innate immune response is mediated by particular cells, the cytokine and chemokine products of those cells, natural antibodies and certain T lymphocytes, all providing rapid and nonspecific effector responses to control virus entry and spread. The cells involved also play an especial role linking innate and adaptive immune responses. Virus specific adaptive immune responses in animals are mediated by both cellular and humoral responses, and the nature of the immune response generated by different individuals infected with the same virus can be different. Strong influences on these responses are exerted by the genetics of the individual as well as environmental influences, which can determine the course and pathogenesis of the infection. Innate immunity provides constant protection against viral infections and previous exposure to a particular virus is not required to activate these mechanisms. In contrast, adaptive immunity develops only after exposure to a virus, and is specific to that particular strain of virus and, sometimes, its close relatives. Adaptive immunity involves cell and antibody (humoral) mediated effector mechanisms, by T and B lymphocytes, respectively. In further contrast to innate immunity, adaptive immune responses exhibit memory, such that the response may be quickly reactivated after re-exposure to the same virus. With many systemic viral infections, immunological memory after natural infection confers long-term, often life-long, protection against the associated disease. The development of efficacious vaccines has substantially reduced the deleterious impact of viral diseases of humans and animals. The goal of vaccination is to stimulate the adaptive immune responses that protect animals from infection with specific viruses. An increasing variety of vaccine types are now commercially available for use in animals, especially companion and production animal species. These include inactivated or killed virus antigen, live/attenuated or modified-live virus, various types of recombinant viruses, viral genes “vectored” by virus constructs and genetically engineered vaccines. Vaccines are used extensively in regulatory programs for the control of individual viral diseases of livestock, often in combination with specific management procedures and are a critical part of the medical care of companion pets