title: Comparative Efficacy of Feline Leukemia Virus (FeLV) Inactivated Whole-Virus Vaccine and Canarypox Virus-Vectored Vaccine during Virulent FeLV Challenge and Immunosuppression.
abstract: Four vaccines for feline leukemia virus (FeLV) are available in the United States. This study's purpose was to compare the efficacy of Nobivac feline 2-FeLV (an inactivated, adjuvanted whole-virus vaccine) and PureVax recombinant FeLV (a live, canarypox virus-vectored vaccine) following FeLV challenge. Cats were vaccinated at 9 and 12 weeks with Nobivac feline 2-FeLV (group A, n = 11) or PureVax recombinant FeLV (group B, n = 10). Group C (n = 11) comprised unvaccinated controls. At 3 months postvaccination, cats were immunosuppressed and challenged with FeLV-A/61E. The outcomes measured were persistent antigenemia at 12 weeks postchallenge (PC) and proviral DNA and viral RNA at 3 to 9 weeks PC. Persistent antigenemia was observed in 0 of 11 cats in group A, 5 of 10 cats in group B, and 10 of 11 cats in group C. Group A was significantly protected compared to those in groups B (P < 0.013) and C (P < 0.0001). No difference was found between groups B and C (P > 0.063). The preventable fraction was 100% for group A and 45% for group B. At 9 weeks PC, proviral DNA and viral RNA were detected 1 of 11 cats in group A, 6 of 10 cats in group B, and 9 of 11 cats in group C. Nucleic acid loads were significantly lower in group A than in group C (P < 0.01). Group A had significantly lower proviral DNA loads than group B at weeks 6 to 9 (P < 0.02). The viral RNA loads were significantly lower in group A than in group B at weeks 7 to 9 (P < 0.01). The results demonstrate that Nobivac feline 2-FeLV-vaccinated cats were fully protected against persistent antigenemia and had significantly smaller amounts of proviral DNA and plasma viral RNA loads than PureVax recombinant FeLV-vaccinated cats and unvaccinated controls.
authors.affiliation: Merck Animal Health, Elkhorn, Nebraska, USA.
authors.forename: M
authors.initials: M
authors.lastname: Patel
authors.affiliation: Merck Animal Health, Elkhorn, Nebraska, USA.
authors.forename: K
authors.initials: K
authors.lastname: Carritt
authors.affiliation: Merck Animal Health, Elkhorn, Nebraska, USA.
authors.forename: J
authors.initials: J
authors.lastname: Lane
authors.affiliation: Merck Animal Health, Elkhorn, Nebraska, USA.
authors.forename: H
authors.initials: H
authors.lastname: Jayappa
authors.affiliation: Merck Animal Health, Madison, New Jersey, USA.
authors.forename: M
authors.initials: M
authors.lastname: Stahl
authors.affiliation: Merck Animal Health, Madison, New Jersey, USA melissa.bourgeois@merck.com.
authors.forename: M
authors.initials: M
authors.lastname: Bourgeois
mesh_terms: D000818:Animals; D000956:Antigens, Viral / Q000097:blood; D028121:Canarypox virus / Q000235:genetics*; D002371:Cat Diseases / Q000517:prevention & control* / Q000821:virology*; D002415:Cats; D004279:DNA, Viral / Q000097:blood; D004337:Drug Carriers; D005256:Leukemia Virus, Feline / Q000276:immunology*; D012367:RNA, Viral / Q000097:blood; D012192:Retroviridae Infections / Q000517:prevention & control / Q000662:veterinary* / Q000821:virology; D016896:Treatment Outcome; D014412:Tumor Virus Infections / Q000517:prevention & control / Q000662:veterinary* / Q000821:virology; D014481:United States; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000276:immunology; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000276:immunology; D019562:Viral Load; D014765:Viral Vaccines / Q000008:administration & dosage / Q000276:immunology*; D014766:Viremia / Q000517:prevention & control
chemical_list: D000956:Antigens, Viral; D004279:DNA, Viral; D004337:Drug Carriers; D012367:RNA, Viral; D015164:Vaccines, Inactivated; D014614:Vaccines, Synthetic; D014765:Viral Vaccines