Clinical Studies

Published Clinical Studies

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Antibodies Induced by Repeated Borrella Burgdorferi Vaccine Administration are Not Detected in Vise-Derived C6 Peptide

Stillman, Thacher, Beall, Goldstein, Lappin, O'Conner, Chandrashekar

Introduction

Introduction of Lyme disease vaccines for use in canines has led to the widespread use of vaccine in Lyme disease-endemic areas of the United States. The SNAP 4Dx Plus Test Kit uses 8orrelia-specific peptide (C6 peptide) for detection of antibody to 8orrelia burgdorferi. Numerous published scientific articles have documented that those immunoassays incorporating the C6 peptide as the target diagnostic antigen failed to react with sera from vaccinated dogs. The purpose of the study was to test sera from vaccinated dogs using the CG-peptide-based microtiter format ELISA and SNAP 4Dx Plus test to demonstrate that these tests are non-reactive with samples from dogs receiving repeated vaccinations. 

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Bacterin That Induces Anti-OspA and Anti-OspC Borreliacidal Antibodies Provides a High Level of Protection Against Canine Lyme Disease

Rhonda L. LaFleur, Jennifer C. Dant, Terri L. Wasmoen, Steven M. Callister, Dean A Jobe, Steven D. Lovrich, Thomas F. Warner, 0. Abdelmagid, and Ronald F. Schell

Groups of 15 laboratory-bred beagles were vaccinated and boosted with either a placebo or adjuvanted bivalent bacterin comprised of a traditional Borrelia burgdorferi strain and a unique ospA- and ospB-negative B. burgdorferi strain that expressed high levels of OspC and then challenged with B. burgdorferi-infected Ixodes scapularis ticks. The vaccinated dogs produced high titers of anti-OspA and anti-OspC borreliacidal antibodies, including borreliacidal antibodies specific for an epitope within the last seven amino acids at the OspC carboxy terminus (termed OspC7) that was conserved among pathogenic Borrelia genospecies. In addition, spirochetes were eliminated from the infected ticks that fed on the bacterin recipients, B. burgdorferi was not isolated from the skin or joints, and antibody responses associated specifically with canine infection with B. burgdorferi were not produced. In contrast, B. burgdorferi was recovered from engorged ticks that fed on 13 (87%) placebo­vaccinated dogs (P < 0.0001), skin biopsy specimens from 14 (93%) dogs (P < 0.0001), and joint tissue specimens from 8 (53%) dogs (J’ = 0.0022). In addition, 14 (93%) dogs developed specific antibody responses against B. burgdorferi proteins, including 11 (73%) with C6 peptide antibodies (P < 0.0001). Moreover, 10 (67%) dogs developed Lyme disease-associated joint abnormalities (P < 0.0001), including 4 (27%) dogs that developed joint stiffness or lameness and 6 (40%) that developed chronic joint inflammation (synovitis). The results therefore confirmed that the bacterin provided a high level of protection against Lyme disease shortly after immunization.

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Canine Infectious Respiratory Disease Complex

Leah A. Cohn, DVM, PhD, DACVIM

CIRDC refers to a contagious cough caused by one or more viral or bacterial pathogens. Laymen often refer to CIRDC as “kennel cough” because of its frequent association with dogs that have been recently housed in kennels or shelters. These settings allow for physical proximity of animals (which facilitates contagion spread) and contribute to disease susceptibility and morbidity in other ways, too. Difficulties associated with sanitation in large groups of dogs, poor air quality, the continual exposure to new animals with additional new pathogens, and the stress associated with kenneling cannot be overestimated as a proximate factor in CIRDC. In fact, potentially pathogenic microbes that often cause subclinical infection or very mild illness in well-acclimated, laboratory-raised dogs can cause severe disease in dogs exposed in less favorable settings.

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Comparative Efficacy of Feline Leukemia Virus Inactivated Whole Virus Vaccine and Canarypox Virus-Vectored Vaccine by Modern Molecular Assays and Conventional Parameters

M. Patel, K. Carritt, J. Lane, H. Jayappa, M. Stahl

Purpose

The purpose of this study was to compare the efficacy of two commercially available feline leukemia vaccines, Nobivac® Feline 2-FeLV (inactivated whole virus vaccine) and PureVax® Recombinant FeLV (live canarypox virus-vectored vaccine) following challenge with virulent feline leukemia virus.

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Comparison of the Mucosal Immune Response in Dogs Vaccinated with Either an Intranasal Avirulent Live Culture or a Subcutaneous Antigen Extract Vaccine of Bordetella bronchiseptica

Randy Davis, BS, Huchappa Jayappa, MVSc, PhD, Omar Y. Abdelmagid, BVSc, MS, PhD, Rob Armstrong, DVM, DVSc, Diane Sweeney, PhD, Craig Lehr, BS

Clinical Relevance

Healthy dogs with low antibody titer to Bordetella bronchiseptica were vacci-nated intranasally with an avirulent live vaccine, subcutaneously with an antigen extract vaccine, or subcutaneously and intranasally with a placebo. Intranasally vaccinated dogs developed B. bronchiseptica–specific IgA titers in nasal secre-tions that remained at high levels until the end of the study; dogs vaccinated subcutaneously with the antigen extract or placebo did not develop measurable antigen-specific IgA titers in nasal secretions. Dogs were challenged with viru-lent live B. bronchiseptica 63 days after vaccination. Intranasally vaccinated dogs had significantly lower cough scores (P ≤ .0058) and shed significantly fewer challenge organisms (P < .0001) than dogs in either of the other groups. Cough scores of subcutaneously vaccinated dogs were not significantly differ-ent from placebo-vaccinated dogs.

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Comparitive Efficacy of Feline Leukemia Virus Inactivated Whole Virus Vaccine and Canarypox Virus-Vectored Vaccine by Molecular Assays and Conventional Parameters

M. Patel, K. Carritt, J. Lane, H. Jayappa, M. Stahl

Purpose

The purpose of this study was to compare the efficacy of two commercially available feline leukemia vaccines, Nobivac® Feline 2-FeLV (inactivated whole virus vaccine) and PureVax® Recombinant FeLV (live canarypox virus-vectored vaccine) following challenge with virulent feline leukemia virus.

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Demonstration of 1-Year Duration of Immunity for Attenuated Bordetella bronchiseptica Vaccines in Dogs

Craig Lehr, BS, Huchappa Jayappa, MVSc, PhD, Jason Erskine, BS, Alicia Brown, BS, Diane Sweeney, PhD, Terri Wasmoen, PhD

Three groups of healthy dogs with low antibody titers to Bordetella bronchisepti-ca (Bb), canine parainfluenza virus (CPI), and canine adenovirus type 2 (CAV-2) were used in this study. One group was vaccinated with a single dose of mono-valent attenuated Bb vaccine and one group with a trivalent vaccine containing attenuated Bb, CPI, and CAV-2; dogs were vaccinated intranasally with a single dose of the respective vaccines. The third group served as unvaccinated controls. All vaccinated dogs subsequently developed serum antibody titers to Bb that per-sisted for at least 1 year. Following Bb challenge 1 year after vaccination, all vac-cinated dogs, regardless of group, showed significantly fewer clinical signs and shed significantly fewer challenge organisms than unvaccinated controls. These results demonstrate that intranasal administration of a single dose of monovalent attenuated Bb vaccine or trivalent vaccine containing attenuated Bb, CPI, and CAV-2 provides 1 year of protection against Bb.

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Diagnosing and Managing Canine Leptospirosis: IDEXX Reference Laboratories Introduces a RealPCR™ Test for Canine Leptospirosis

IDEXX Reference Laboratories

Leptospirosis, a zoonotic disease of worldwide significance, is caused by spirochetes of the genus Leptospira. Leptospirosis has been thought to most commonly affect young-adult, large-breed, outdoor dogs; however, small dogs in urban areas can also contract the disease. Pathogenic serovars infecting dogs include icterohaemorrhagiae, canicola, pomona, bratislava, grippotyphosa and autumnalis. Although serovar identification is of interest from an epidemiologic stand point, clinical disease is similar for all serovars and treatment is the same. Therefore, determining whether a dog has leptospirosis is much more important than identification of which specific serovar is involved.

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Disease & Mortality Study

Read the study which proves high efficacy of Nobivac® Lepto₄ vaccine under severe challenge.

Prevention of Disease and Mortality in Vaccinated Dogs Following Experimental Challenge With Virulent Leptospira.

R LaFleur, J Dant, T Wasmoen. Intervet / Schering Plough Animal Health, Elkhorn, NE.

Canine Leptospirosis can vary from subclinical infection to illness that ranges from mild to severe, including death, depending on the susceptibility of the dog, virulence of the organism, and route and degree of infection. The objective of this study was to evaluate the ability of a canine Leptospira bacterin to prevent infection and disease following challenge with virulent Leptospira canicola, L. pomona, L. grippotyphosa, or L. icterohaemorrhagiae. Groups of 8-week-old beagles were vaccinated (day 0) and boosted (day 21) with placebo (n = 10) or the 4-way bacterin (n ≥ 20) and subsequently challenged with each serovar. The results demonstrated that blood and various tissue samples from placebo-recipients became reliably infected, and the dogs developed typical clinical signs of Leptospirosis including loss of appetite, ocular congestion, depression, dehydration, jaundice, hematuria, melena, vomiting, petechiae, and death. In addition, placebo-recipients developed kidney and liver dysfunction. In contrast, some vaccine-recipients became infected, but the organisms were cleared quickly from the blood. Vaccinated dogs failed to develop severe clinical disease requiring medical intervention, and no animals died (p > 0.001). A few of the vaccinated dogs developed clinical abnormalities, but the clinical signs remained mild and were self-limiting (p < 0.0001 for each serovar). Administration of the bacterin also prevented thrombocytopenia (p < 0.0001), kidney complications caused by L. canicola (p < 0.0001), L. icterohaemorrhagiae (p < 0.0001), and L. pomona (p = 0.012), and liver dysfunction caused by L. pomona (p < 0.0001) and L. grippotyphosa (p < 0.0001). The results therefore confirmed that vaccinating dogs with the 4-way Leptospira bacterin provided a high degree of protection (99.5%-100%) against the clinical signs of Leptospirosis including mortality.

Efficacy of an Inactivated FeLV Vaccine Compared to a Recombinant FeLV Vaccine in Minimum Age Cats Following Virulent FeLV Challenge

Kristin Stuke, Vickie King, Kendra Southwick, Mira I. Stoeva, Anne Thomas, M. Teresa C. Winkler

Abstract

The aim of the study was to determine the efficacy of an inactivated feline leukemia virus (FeLV) vac-cine (Versifel® FeLV, Zoetis.) compared to a recombinant FeLV vaccine (Purevax® FeLV, Merial Animal Health) in young cats, exposed under laboratory conditions to a highly virulent challenge model. The study was designed to be consistent with the general immunogenicity requirements of the European Pharma-copoeia 6.0 Monograph 01/2008:1321—Feline Leukaemia Vaccine (Inactivated) with the exception that commercial-strength vaccines were assessed. Fifty seronegative cats (8–9 weeks old) were vaccinated subcutaneously on two occasions, three weeks apart, with either placebo (treatment group T01), Versifel FeLV Vaccine (treatment group T02), or Purevax FeLV Vaccine (treatment group T03) according to the manufacturer’s directions. Cats were challenged three weeks after the second vaccination with a virulent FeLV isolate (61E strain). Persistent FeLV antigenemia was determined from 3 to 15 weeks postchallenge. Bone marrow samples were tested for the presence of FeLV proviral DNA to determine FeLV latent infec-tion. At week 15 after challenge with the virulent FeLV 61E strain, the Versifel FeLV Vaccine conferred 89.5% protection against FeLV persistent antigenemia and 94.7% protection against FeLV proviral DNA integration in bone marrow cells. In comparison, the Purevax FeLV Vaccine conferred 20% protection against FeLV persistent antigenemia and 35% protection against FeLV proviral DNA integration in bone marrow cells following challenge. The data from this study show that the Versifel FeLV Vaccine was effi-cacious in preventing both FeLV persistent p27 antigenemia and FeLV proviral DNA integration in bone marrow cells of cats challenged with this particular challenge model under laboratory conditions and provided better protection than Purevax FeLV in this experimental challenge model with highly virulent FeLV.

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Feline Leukaemia Virus: a Review­ of Immunity and Vaccination

A. H. Sparkes

The availability of feline leukaemia virus {FeLV) vaccines has added a new and important dimension to the control of this infectious agent. FeLV vaccination is a controversial issue, however, partly because of differences in the formulation between the current products, partly because of conflicting claims by vaccine manufacturers and partly because experimental trials have shown that none of the vaccines provides 100 per cent protection against infection. This paper reviews the role of the immune response in determining the outcome following exposure to FeLV and describes the importance of FeLV subgroups. The five commercial FeLV vaccines currently available in the USA and Europe are described and the published literature on efficacy studies is summarised. However, these efficacy studies are often difficult to interpret for various reasons, including the small numbers of animals used; differences in challenge methods, vaccine strains and vaccine dose employed; and differences in postchallenge monitoring protocols.

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Feline Leukemia Virus Immunity Induced by Whole Inactivated Virus Vaccination

Andrea N. Torres, Kevin P. O’Halloran, Laurie J. Larson, Ronald D. Schultz, Edward A. Hoover

Abstract

A fraction of cats exposed to feline leukemia virus (FeLV) effectively contain virus and resist persistent antigenemia/viremia. Using real-time PCR (qPCR) to quantitate circulating viral DNA levels, previously we detected persistent FeLV DNA in blood cells of non-antigenemic cats considered to have resisted FeLV challenge. In addition, previously we used RNA qPCR to quantitate circulating viral RNA levels and determined that the vast majority of viral DNA is transcriptionally active, even in the absence of antigenemia. A single comparison of all USDA-licensed commercially available FeLV vaccines using these modern sensitive methods has not been reported. To determine whether FeLV vaccination would prevent nucleic acid persistence, we assayed circulating viral DNA, RNA, antigen, infectious virus, and virus neutralizing (VN) antibody in vaccinated and unvaccinated cats challenged with infectious FeLV. We identified challenged vaccinates with undetectable antigenemia and viremia concomitant with persistent FeLV DNA and/or RNA. Moreover, these studies demonstrated that two whole inactivated virus (WIV) adjuvanted FeLV vaccines (Fort Dodge Animal Health’s Fel-O-Vax Lv-K1 and Schering-Plough Animal Health’s FEVAXYN FeLV1) provided effective protection against FeLV challenge. In nearly every recipient of these vaccines, neither viral DNA, RNA, antigen, nor infectious virus could be detected in blood after FeLV challenge. Interestingly, this effective viral containment occurred despite a weak to undetectable VN antibody response. The above findings reinforce the precept of FeLV infection as a unique model of effective retroviral immunity elicited by WIV vaccination, and as such holds valuable insights into retroviral immunoprevention and therapy.

lmmunogenicity and Efficacy of a Commercial Feline Leukemia Virus Vaccine

Niels C. Pedersen, DVM, PhD

Twenty young adult specific pathogen-free cats were randomly divided into two groups of 10 animals each. One group was vaccinated with two doses of feline leukemia virus vaccine according to the manufac­turer’s recommendations. All 20 cats were challenge exposed oronasally (4 times over a I-week period), beginning 3 weeks after immunization, with a virulent subgroup A strain of FeLV (CT600-FeLV). The severity of the FeL V infection was enhanced by treating the cats with methylprednisolone acetate at the time of the last FeL V exposure. Ten of 10 non vaccinated cats became persistently viremic compared with 0/10 of the vaccinates. ELISA antibodies to whole FeLV were present at high concentrations after immunization in all of the vaccinated cats, and there was no observable anamnestic antibody response after challenge exposure. ELISA antibodies to whole FeL V appeared at low concentrations in the serum of nonvaccinated cats after infection but disappeared as the viremia became permanently established. Virus neutralizing antibodies were detected in 3 /10 vaccinates and O /10 non vaccinates immediately before FeLV challenge exposure, and in 8/10 vaccinates and 1/10 nonvaccinates 5 weeks later. Although vaccination did not consistently evoke virus neutralizing antibodies, it appeared to immunologically prime cats for a virus-neutralizing antibody response afterinfection. Active FeL V infection was detected in bone marrow cells taken 14 weeks after infection from 10/10 nonvaccinates and 0/10 vaccinates. Latent FeLV infection was not detected in bone marrow cells from any of the vaccinated cats 14 weeks after challenge exposure. (Journal of Veterinary Internal Medicine 1993; 7:34-39)

One-Year Duration of Immunity Induced by Vaccination with a Canine Lyme Disease Bacterin

Rhonda L. LaFleur, Steven M. Callister, Jennifer C. Dant, Dean A. Jobe, Steven D. Lovrich, Thomas F. Warner, Terri L. Wasmoen, and Ronald F. Schell

Laboratory-reared beagles were vaccinated with a placebo or a bacterin comprised of Borrelia burgdorferi S-1-10 and ospA-negative/ospB-negative B. burgdorferi 50772 and challenged after 1 year with B. burgdorferi­infectedlxodes scapu/aris ticks. For the placebo recipients, spirochetes were recovered from 9 (60%) skin biopsy specimens collected after 1 month, and the organisms persisted in the skin thereafter. Ten (67%) dogs also developed joint infection (3 dogs), lameness or synovitis (7 dogs), or B. burgdorferi-specifi.c antibodies (8 dogs). For the vaccine recipients, spirochetes were recovered from 6 (40%) skin biopsy specimens collected after 1 month. However, subsequent biopsy specimens were negative, and the dogs failed to develop joint infection (P = 0.224), lameness/synovitis (P = 0.006), or Lyme disease-specific antibody responses (P = 0.002). The bacterin provided a high level of protection for 1 year after immunization, and the addition of the OspC­producing B. burgdorferi 50772 provided enhanced protection.

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Prevalance of Canine Infectious Respiritory Disease Complex Pathogens in Dogs in the Chicago Region (March-April 2015)

Jill A. Richardson, Amy Glaser, Nyssa Reine-Salz, Edward J. Dubovi

Canine infectious respiratory disease complex (CIRDC) is a common disease complex caused by many different viruses and bacteria, including Bordetella bronchiseptica, Mycoplasma cynos, adenovirus type 2, distemper, influenza A virus, parainfluenza virus, pneumovirus and respiratory coronavirus. In March 2015, veterinarians in the Chicago area noted an increase in incidence of signs of canine infectious respiratory disease in dogs. Nasal and pharyngeal swabs from dogs showing clinical signs were submitted to the Cornell University Animal Health Diagnostic Center (AHDC). A canine respiratory polymerase chain reaction (PCR) screening panel was utilized which allows identification of the following CIRDC pathogens: B. bronchiseptica, Mycoplasma cynos, adenovirus type 2, distemper, influenza A, parainfluenza virus, pneumovirus and respiratory coronavirus.

Three-Year Duration of Immunity in Cats Following Vaccination against Feline Rhinotracheitis Virus, Feline Calicivirus, and Feline Panleukopenia Virus

T. C. Gore, N. Lakshmanan, J. R. Williams, F. F. Jirjis, S. T. Chester, K. L. Duncan, M. J. Coyne, M. A. Lum, and F. J. Sterner

Clinical Relevance

Forty-two seronegative cats received an initial vaccination at 8 weeks of age and a booster vaccination at 12 weeks. All cats were kept in strict isolation for 3 years after the second vaccination and then were challenged with feline calicivirus (FCV) or sequentially challenged with feline rhinotracheitis virus (FRV) followed by feline panleukopenia virus (FPV). For each viral challenge, a separate group of 10 age-matched, nonvaccinated control cats was also challenged. Vaccinated cats showed a statistically significant reduction in virulent FRV-associated clinical signs (P = .015), 100% protection against oral ulcers associated with FCV infec-tion (P < .001), and 100% protection against disease associated with virulent FPV challenge (P < .005). These results demonstrated that the vaccine provided pro-tection against virulent FRV, FCV, and FPV challenge in cats 8 weeks of age or older for a minimum of 3 years following second vaccination.

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Three-Year Duration of Immunity in Dogs Following Vaccination Against Canine Adenovirus Type-1, Canine Parvovirus, and Canine Distemper Virus

Thomas C. Gore, PhD, Nallakannu Lakshmanan, MVSc, PhD, Karen L. Duncan, DVM, MS, DABVT, Michael J. Coyne, VMD, PhD, Melissa A. Lum, PhD, Frank J. Sterner, MBA, PhD

Clinical Relevance

A challenge-of-immunity study was conducted to demonstrate immunity in dogs 3 years after their second vaccination with a new multivalent, modified-live vaccine containing canine adenovirus type-2, canine parvovirus (CPV), and ca-nine distemper virus (CDV). Twenty-three seronegative pups were vaccinated at 7 and 11 weeks of age. Eighteen seronegative pups, randomized into groups of six dogs, served as challenge controls. Dogs were kept in strict isolation for 3 years following the last vaccination and then challenged sequentially with viru-lent canine adenovirus type-1 (CAV-1), CPV, and CDV. For each viral challenge, a separate group of six control dogs was also challenged. Clinical signs of CAV-1, CPV, and CDV infections were prevented in 100% of vaccinated dogs, demonstrating that the multivalent, modified-live test vaccine provided protec-tion against virulent CAV-1, CPV, and CDV challenge in dogs 7 weeks of age or older for a minimum of 3 years following second vaccination.

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Urinary Shedding Challenge Study

Read the study which proves Nobivac® Canine 1-DAPPv+L₄ effectively protects against leptospiremia and leptospiruria of (4) serovars.

Prevention of Leptospiremia and Leptospiruria Following Vaccination With a DAPPv + 4-way Leptospira Combination Vaccine

Rhonda L. LaFleur, Jennifer C. Dant, Anna L. Tubbs, Huchappa Jayappa, David Sutton, Ian Tarpey

Background: Leptospirosis, characterized by high fever, anorexia, vomiting, abdominal pain, diarrhea, myalgia, polyuria/polydipsia, jaundice, epistaxis, hematuria, and/or reproductive failure, continues to cause considerable morbidity among infected canines. Direct transmission of Leptospira spp. occurs when dogs come into contact with infected urine or ingest infected tissue. After dogs become infected, the spirochetes circulate in the blood for several days1,3 where they cause extensive damage to the endothelium of small blood vessels (leptospiremia). After the leptospiremic phase, the spirochetes can further colonize various organs, including the kidneys, where dogs can become a carrier and potentially shed organisms in the urine for months (leptospiruria). Leptospira interrogans serovars Canicola and Icterohaemorrhagiae are traditional causative agents of canine leptospirosis, and while the use of bacterins have decreased the prevalence of the disease, significant morbidity can still be attributed to infection with these serovars.

Aim of the Work: In this study, we combined inactivated L interrogans serovars Canicola, Pomona, and Icterohaemorrhagiae and L kirschneri serovar Grippotyphosa with Nobivac® Canine 1-DAPPv (Animal Health at Merck & Co., Inc., Kenilworth, NJ USA), a commercially available vaccine that contains modified live canine distemper virus, adenovirus, parainfluenza virus, and parvovirus. We then vaccinated dogs with the combination product and evaluated the ability of the vaccination to prevent leptospiremia and leptospiruria following challenge with viable organisms of each serovar.

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