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
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.
Available from: Brian James Willett
- "and contact challenge , with protection also extending to heterologous challenge . 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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ABSTRACT: Across human and veterinary medicine, vaccines against only two retroviral infections have been brought to market successfully, the vaccines against feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV). FeLV vaccines have been a global success story, reducing virus prevalence in countries where uptake is high. In contrast, the more recent FIV vaccine was introduced in 2002 and the degree of protection afforded in the field remains to be established. However, given the similarities between FIV and HIV, field studies of FIV vaccine efficacy are likely to advise and inform the development of future approaches to HIV vaccination. Here we assessed the neutralising antibody response induced by FIV vaccination against a panel of FIV isolates, by testing blood samples collected from client-owned vaccinated Australian cats. We examined the molecular and phenotypic properties of 24 envs isolated from one vaccinated cat that we speculated might have become infected following natural exposure to FIV. Cats vaccinated against FIV did not display broadly neutralising antibodies, suggesting that protection may not extend to some virulent recombinant strains of FIV circulating in Australia.
Copyright © 2015. Published by Elsevier Ltd.
Available from: ncbi.nlm.nih.gov
- "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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ABSTRACT: Studying the evolutionary mechanisms of feline immunodeficiency virus in the domestic cat (Felis catus), FIV(Fca), provides a good comparison to other lentiviruses, such as HIV and FIV(Pco) in the cougar (Puma concolor). We review the current epidemiological and evolutionary findings of FIV(Fca). In addition to the five accepted FIV(Fca), subtypes, several recent phylogenetic studies have found strains that form separate clades, indicative of novel subtypes. In New Zealand cats, these strains of unknown subtype have been found to be involved in complex patterns of intergenic recombination, and whole genome sequences are required to resolve these. Evidence of recombination events has been documented with the highest levels in the env gene, the region involved in host cell receptor recognition. Several cases of FIV(Fca) multiple infections, both inter- and intra-subtype, have been reported. The findings of both unknown subtypes and relatively high levels of recombination suggest the need for further testing of the current vaccine. Limited studies on the evolutionary rate of FIV(Fca) document a value twice to three times that of FIV in the cougar, a result suggesting the different levels of co-adaptation between the viruses and their respective hosts. We studied the tissue distribution of FIV(Fca) in feral domestic cats, finding the first case of FIV compartmentalisation, a phenomenon well documented in HIV-1 patients.
Available from: Katrin Hartmann
- "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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ABSTRACT: Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are among the most common infectious diseases of cats. Although vaccines are available for both viruses, identification and segregation of infected cats form the cornerstone for preventing new infections. Guidelines in this report have been developed for diagnosis, prevention, treatment, and management of FeLV and FIV infections. All cats should be tested for FeLV and FIV infections at appropriate intervals based on individual risk assessments. This includes testing at the time of acquisition, following exposure to an infected cat or a cat of unknown infection status, prior to vaccination against FeLV or FIV, prior to entering group housing, and when cats become sick. No test is 100% accurate at all times under all conditions; results should be interpreted along with the patient's health and risk factors. Retroviral tests can diagnose only infection, not clinical disease, and cats infected with FeLV or FIV may live for many years. A decision for euthanasia should never be based solely on whether or not the cat is infected. Vaccination against FeLV is highly recommended in kittens. In adult cats, antiretroviral vaccines are considered non-core and should be administered only if a risk assessment indicates they are appropriate. Few large controlled studies have been performed using antiviral or immunomodulating drugs for the treatment of naturally infected cats. More research is needed to identify best practices to improve long-term outcomes following retroviral infections in cats.
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