Search Results

Abstract

Objective—To examine the correlation between results for an indirect immunofluorescence assay (IFA) that uses Ehrlichia canis antigen as a substrate (ie, E canis-IFA), 2 western blot (WB) analyses, and a commercially available ELISA in the detection of E canis antibody in dog sera.

Sample Population—54 canine serum samples that were reactive on E canis-IFA and 16 canine serum samples that were E canis-IFA nonreactive.

Procedure—Serum samples were evaluated by use of 2 WB analyses and a commercially available ELISA. Correlation between results of the 3 testing modalities (ie, IFA, WB analyses, and the ELISA) was examined by use of nonreactive (E canis-IFA reciprocal titer, < 20), low-titer (reciprocal titer, 80 to 160), medium-titer (reciprocal titer, 320 to 2,560), and high-titer (reciprocal titer, 5,120 to > 20,480) serum samples.

Results—For all serum samples in the nonreactive (n = 16), medium-titer (17), and high-titer (18) groups, correlation of results among IFA, WB analyses, and the commercially available ELISA was excellent. A poor correlation was found between IFA results and those of WB analyses and the ELISA for serum samples in the low-titer group (19), with only 4 of the 19 serum samples having positive results on both WB analyses and the commercially available ELISA.

Conclusions and Clinical Relevance—The discrepancy between E canis-IFA, WB analyses, and the commercially available ELISA results for the low-titer serum samples may be related to a high IFA sensitivity or, more likely, a lack of specificity associated with cross-reactivity among Ehrlichia spp.

Abstract

Objective−To report the prevalence of bovine viral diarrhea virus (BVDV) in calves and calf groups (ie, calves from the same farm) in beef breeding herds and evaluate the ability of biosecurity risk assessment questionnaires to identify calf groups with positive results for BVDV.

Design−Nonrandom survey.

Animals−12,030 calves born in spring from 102 operations.

Procedures−Cow-calf producers that voluntarily enrolled in a screening project submitted ear notch specimens from calves and answered a 29-question survey instrument. Ear notch specimens were tested for BVDV with an antigen-capture ELISA (ACE), and ear notch specimens with positive ACE results for BVDV were immediately retested by performing immunohistochemistry (IHC). Follow-up testing, 3 to 4 weeks after initial positive ACE results, was done by use of a second IHC test and virus isolation on a subsequently submitted ear notch specimen from the same calves to identify those that were persistently infected (PI).

Results−102 producers submitted ear notch specimens for BVDV screening. Initially, 24 of 12,030 calves had positive ACE results for BVDV. A second ear notch specimen was submitted for 20 of these 24 calves. Of 20 retested calves, 12 had positive ICH results for BVDV, confirming PI status. The 12 PI calves came from 4 calf groups (3 singletons and 1 calf group with 9 PI calves).

Conclusions and Clinical Relevance−Prevalence of BVDV in calf groups was low, and questions designed to identify high-risk biosecurity behaviors had little value in identifying calf groups with positive results for BVDV.

Abstract

Objective—To evaluate the sensitivity and specificity of a commercially available in-clinic ELISA for detection of heartworm infection and tick-borne diseases in dogs.

Sample Population—846 serum, plasma, or blood samples obtained from dogs.

Procedures—Samples were evaluated via the in-clinic ELISA to detect antibodies against Anaplasma phagocytophilum, Ehrlichia canis, and Borrelia burgdorferi and Dirofilaria immitis (heartworm) antigen. True infection or immunologic status of samples was assessed by use of results of necropsy, an antigen assay for D immitis, and immunofluorescence assay or western blot analysis for antibodies against B burgdorferi, E canis, and A phagocytophilum.

Results—Sensitivity and specificity of the in-clinic ELISA for detection of heartworm antigen (99.2% and 100%, respectively), antibodies against B burgdorferi (98.8% and 100%, respectively), and antibodies against E canis (96.2% and 100%, respectively) were similar to results for a similar commercial ELISA. In samples obtained from dogs in the northeast and upper Midwest of the United States, sensitivity and specificity of the in-clinic ELISA for antibodies against Anaplasma spp were 99.1% and 100%, respectively, compared with results for an immunofluorescence assay. Samples from 2 dogs experimentally infected with the NY18 strain of A phagocytophilum were tested by use of the in-clinic ELISA, and antibodies against A phagocytophilum were detected by 8 days after inoculation. Antibodies against Anaplasma platys in experimentally infected dogs cross-reacted with the A phagocytophilum analyte. Coinfections were identified in several of the canine serum samples.

Conclusions and Clinical Relevance—The commercially available in-clinic ELISA could be used by veterinarians to screen dogs for heartworm infection and for exposure to tick-borne pathogens.

Abstract

Objective—To evaluate the long-term protective immunity of a cyprinid herpesvirus 3 (CyHV3) vaccine in naïve koi (Cyprinus carpio koi).

Animals—72 koi.

Procedures—Vaccinated koi (n = 36) and unvaccinated control koi (36) were challenge exposed to a wild-type CyHV3 strain (KHVp8 F98-50) 13 months after vaccination.

Results—The CyHV3 vaccine provided substantial protective immunity against challenge exposure. The proportional mortality rate was less in vaccinated koi (13/36 [36%]) than in unvaccinated koi (36/36 [100%]). For koi that died during the experiment, mean survival time was significantly greater in vaccinated than in unvaccinated fish (17 vs 10 days).

Conclusions and Clinical Relevance—The CyHV3 vaccine provided substantial protective immunity against challenge exposure with CyHV3 13 months after vaccination. This provided evidence that koi can be vaccinated annually with the CyHV3 vaccine to significantly reduce mortality and morbidity rates associated with CyHV3 infection.

Abstract

Objective—To evaluate microtiter-plate format ELISAs constructed by use of different diagnostic targets derived from the Ehrlichia ewingii p28 outer membrane protein for detection of E ewingii antibodies in experimentally and naturally infected dogs.

Sample Population—Serum samples from 87 kenneled dogs, 9 dogs experimentally infected with anti-E ewingii, and 180 potentially naturally exposed dogs from Missouri.

Procedures—The capacities of the synthetic peptide and truncated recombinant protein to function as detection reagents in ELISAs were compared by use of PCR assay, western blot analysis, and a full-length recombinant protein ELISA. Diagnostic targets included an E ewingii synthetic peptide (EESP) and 2 recombinant proteins: a full-length E ewingii outer membrane protein (EEp28) and a truncated E ewingii outer membrane protein (EETp28)

Results—A subset of Ehrlichia canis-positive samples cross-reacted in the EEp28 ELISA; none were reactive in the EESP and EETp28 ELISAs. The EESP- and EETp28-based ELISAs detected E ewingii seroconversion at approximately the same time after infection as the EEp28 ELISAs. In afield population, each of the ELISAs identified the same 35 samples as reactive and 27 samples as nonreactive. Anaplasma and E can is peptides used in a commercially available ELISA platform did not detect anti-E ewingii antibodies in experimentally infected dogs.

Conclusions and Clinical Relevance—The EESP and EETp28 ELISAs were suitable for specifically detecting anti-E ewingii antibodies in experimentally and naturally infected dogs. [Am J Vet Res 2010;71:1195-1200)