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VACCINES. PETER H. RUSSELL, BVSc, PhD, FRCPath, MRCVS Department of Pathology and Infectious Diseases, The Royal Veterinary College, Royal College Street, London NW1 OTU. E-mail Web site. Objectives Students should be able to:.
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VACCINES PETER H. RUSSELL, BVSc, PhD, FRCPath, MRCVS Department of Pathology and Infectious Diseases, The Royal Veterinary College, Royal College Street, London NW1 OTU. E-mailWeb site
ObjectivesStudents should be able to: • summarise the mechanisms of primary and secondary immune responses to virus infections and to vaccines. • compare and contrast different types of vaccine with some veterinary examples. • describe the influence of maternal antibody on vaccination outcome. • list some of possible reasons for the failure of vaccines to protect against disease.
Vaccination involves setting up memory to the virus infection such that a high level of cytotoxic T cells (Tc) and IgG are activated in 1-2 days instead of 4-10 days. These curtail the infection before lesions develop. IgA/IgG at mucosal surfaces are also useful to neutralise virus before entry but is difficult to achieve except by mucosal live vaccines.
The mechanisms of recovery from a primary infection will first be reviewed
The mechanisms of recovery from a primary infection will first be reviewed(cont.)
The mechanisms of recovery from a primary infection will first be reviewed(cont.)
Vaccination Types of field vaccine Maternal antibody and vaccination Reasons for vaccine failure
Types of field vaccine: 1) live (attenuated) 2) inactivated 3) subunit 4) recombinant 5) DNA vaccines, research
1) Live (attenuated) (cont.)
SUMMARY • Vaccines are used for endemic diseases which may then become so rare vaccination can cease • Vaccines induce memory for Tc and VN IgG/IgA but without the risk of disease. • Most commercial vaccines are either inactivated or live-attenuated with the exception of the recombinant FeLV from E.Coli. • Inactivated vaccines are more expensive to produce and often administered with adjuvants • Vaccines must be quality controlled • The vaccination programme must allow for maternal antibody • Vaccines can fail, most usually because of new challenge viruses with altered antigens or increased virulence.