Dual-subtype vaccine (Fel-O-Vax FIV) protects cats against contact challenge with heterologous subtype BFIV infected cats

Department of Veterinary Infectious Disease, School of Veterinary Medicine and Animal Science, Kitasato University, Towada, Aomori 034-8628, Japan.
Veterinary Microbiology (Impact Factor: 2.51). 08/2005; 108(3-4):155-65. DOI: 10.1016/j.vetmic.2005.02.014
Source: PubMed


Fel-O-Vax FIV is a dual-subtype vaccine consisting of inactivated whole viruses of subtype A (Petaluma strain) and subtype D (Shizuoka strain). The efficacy of this vaccine against heterologous subtype A strain challenge was demonstrated, but it is unclear whether the result reflects efficacy in the field. In this study, we evaluated the efficacy of this vaccine against contact challenge by exposing both vaccinated and unvaccinated control animals with cats infected with Aomori-2 strain belonging to subtype B, a subtype prevalent in many regions of the world. Nineteen specific-pathogen-free (SPF) cats were divided into a vaccinated group (six cats), an unvaccinated control group (eight cats), and a challenge group (five cats), and maintained in the same room. Cats were monitored for FIV proviral DNA by nested PCR and for FIV-specific antibody levels by ELISA. After 1 year of commingling, each cat in the vaccinated group was given a booster dose. In addition, the original challenge group was removed and replaced with another challenge group of SPF cats, which were inoculated with the Aomori-2 strain. FIV infection was confirmed in four of the eight animals in the unvaccinated control group by the 29th week in the second year of commingling. In contrast, all of the animals were negative in the vaccinated group. These findings confirmed the efficacy of this vaccine against heterologous stains classified as subtype B, and suggested that the vaccine exhibits broad efficacy against genetically diverse FIV.

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    • "and contact challenge [3], with protection also extending to heterologous challenge [4]. Given the similarities between FIV infection of cats and HIV infection of humans, a broader understanding of the mechanisms of immunity to infection with FIV may inform the development of candidate HIV vaccines. "
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    Vaccine 01/2015; 11(8). DOI:10.1016/j.vaccine.2015.01.028 · 3.62 Impact Factor
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    • "The Fel-O-Vax vaccine (Fort Dodge), which is commercially available in a number of countries including USA, Australia, Japan and NZ, confers protection against subtypes A, B and D but has not yet been tested on subtype C, despite the wide distribution of this subtype (Yamamoto et al., 2002; Kusuhara et al., 2005). Furthermore, the findings of FIV strains of unknown subtypes suggest further testing of the vaccine in cat populations is warranted. "
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    • "In licensing trials required by the United States Department of Agriculture, when cats were challenged with a heterologous clade A FIV subtype 1 year after the initial vaccination series, the vaccine yielded a preventable fraction (defined as the proportion of cats protected by vaccination in excess of the proportion that is naturally resistant) of 82% (Huang et al 2004). Results of two subsequent studies indicate 100% protection against infection with two subtype B FIV strains (Kusuhara et al 2005, Pu et al 2005). Results of a third study in which cats were challenged with subtype A FIV indicated that all vaccinated cats and control cats became infected (Dunham et al 2006). "
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