FIV vaccinated cats more susceptible to FIV infection

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FIV vaccinated cats more susceptible to FIV infection

Postby malernee » Thu Dec 02, 2004 7:04 pm

Further Investigation into the Increased Susceptibility of Cats to Feline Immunodeficiency Virus (FIV) After Vaccination with Parenteral Vaccines.
ACVIM 2003
Pamela J. Berlinski1, Janet K. Gibson1, Nancy J. Forester1 and Stephen Martin1. 1Pharmacia Animal Health, Kalamazoo, Michigan. USA.

Studies were performed to investigate the possibility that some vaccine approaches can induce aspects of immunity that increase the susceptibility of cats to infection with FIV, and to determine if cats are more susceptible to infection shortly after vaccination with commercial products, even if these products are designed to protect against FIV. The initial experiments were performed after cats were vaccinated with subunits of structural FIV antigens produced by recombinant baculoviruses, and after vaccination with commercially available, feline infectious disease vaccines. The second set of experiments was performed after vaccination with a commercial product designed to protect against FIV. After vaccination under various protocols, cats were exposed to various isolates of virulent FIV and the subsequent development of infection was monitored by quantitative PCR techniques.

The first set of experiments demonstrated that some aspects of FIV specific immunity could lead to an increased susceptibility to infection, manifested as the ability to infect cats with a lower challenge dose of virus, and greatly increased plasma viral burdens during the primary viremia. Additionally, a non-specific component of immunization-related increased susceptibility was demonstrated. In a second series of experiments that used in vitro or in vivo derived FIV challenges, this phenomenon was also observed after vaccination with a commercial product designed to protect against FIV. In addition, vaccinated cats that were more susceptible to infection developed quicker and higher virus loads in their saliva, suggesting that they would be more likely to transmit infection via biting.

Thus, cats vaccinated with non-FIV specific antigens or even commercial feline vaccines, including one designed to protect against FIV, are more susceptible to FIV infection, and may become more efficient vectors for spreading new FIV infections.
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