The effect of medication with metichlorpindol and methylbenzoquate on the development of antibodies as measured by the fluorescent antibody (IFA)_test against Eimeria tenella and Eimeria maxima

The development of antibodies as measured by the indirect fluorescent antibody (IFA)_ test was studied in groups of birds infected with Eimeria tenella or E. maxima and fed diets containing methylzoquate (MBQ) and/or meticlorpindol (MCP). The drugs suppressed both the E. tenella and E. maxima infections, the extent depending on the concentrations in the feed. The IFA test titres in both the E. tenella and E. maxima infections were related to the oocyst production. Effective suppression of the infection resulted in on or minimal IFA response. Since both drugs used inhibit the sporozoites, it is concluded that development of the parasite is necessary to stimulate the host to produce circulating fluorescent antibodies.     

Demonstration of circulatinf antibodies to Eimeria tenella by the indirect immunofluorescent antibody test using sprozoites and second-stage schizonts as antigen

In the indirect immunofluorescent antibody (IFA) test using sporozoites as an antigen, sera from chickens immunized via the natural route were positive in dilutions as high as 1 : 1 048. Serum from a rabbit, immunized only to sporozoites by subcuntaneous injection, was positive in a dilution of 1 : 4 4 096. Non-immunized chicken andn rabbit sera were positive in dilutions varying from 1 : 20 to 1 : 64.Sporozoites within sporocytes were not stained. In frozen sections of infected chorioallantoic membranes and ceca, sporozoites were not traced with the IFA test with immunized chicken or rabbit sera. However, with the rabbit serum specific diffuse intraepithelial and subepithelial fluorescence was observed in the ceca from 4 to 11 h after infection.Fluorescence was never associated with the first-stage schzonts and gamates, but second-stage schizonts were positive with both chicken and rabbit serum. The titres obtained with this antigen were about the same as those obtained with sporozoite smears. The possible presence of common antigens in sporozoites and second stage schizints is discussed.     

Prevalence of antibodies to porcine adenovirus in swine by indirect fluorescent antibody test

An indirect fluorescent antibody test was developed for routine identification of a porcine adenovirus and its specific antibody. Two specific-pathogen-free young pigs were inoculated with the viral antigen prepared in continuous porcine kidney cell cultures, and their sera were used as an antibody reagent to standardize the test. Sera of adult pigs with respiratory problems, obtained from pig farms in Quebec, were tested for antibodies to this virus; 83 of 540 sera tested (15.2%) were found to be positive.     

Validation of a commercially available cELISA test for canine neosporosis against an indirect fluorescent antibody test (IFAT)

A commercially available competitive enzyme-linked immunosorbent assay (cELISA, VMRD^®) was validated for the detection of Neospora caninum antibodies in the serum of dogs, using as a reference test an indirect fluorescent antibody test (IFAT, Fuller^®). A partial verification approach was used. A total of 618 dogs were screened with cELISA and a subset of positive and negative sera (n = 237) were then tested with IFAT. Naïve relative sensitivity (SE_nv) and naïve relative specificity (SP_nv) of cELISA were calculated and then corrected (SE_corr; SP_corr) for studies with partial validation. Results showed a SE_nv of 72% and a SP_nv of 89.3%; corrected estimates showed a SE_corr of 47% and a SP_corr of 96%. ROC analysis showed that the cutoff recommended by the manufacturer (30%) corresponded to the highest naïve sensitivity (72%) combined with a good naïve specificity (90%) of cELISA. Corrected estimates of SE and SP for partial verification method revealed that SE of the cELISA is lower and SP is higher than naïve estimates. The results suggest to use this test for confirmation of a clinical suspicion of neosporosis, and to use some techniques for adjustment of misclassification in prevalence and risk-factor studies.     

The indirect fluorescent antibody test (IFAT) for the detection of Nosema cuniculi antibodies in the blue fox (Alopex lagopus).

During recent years nosematosis has been a major problem in the breeding of blue fox in the Scandinavian countries, causing heavy losses among growing pups (Nordstoga 1972, Nordstoga et al. 1974). The lack of reliable methods for diagnosing the infection in live foxes has so far made epizootiologic studies of the disease very difficult. However, reports on the IFAT in rabbits with nosematosis (Cox et al. 1972, Chalupsky et al. 1971, 1973, 1974), encouraged the search for a method of detecting Nosema antibodies in fox sera.     

Serologic response of Babesia equi-infected horses as measured by complement-fixation and indirect fluorescent antibody tests

Both the complement-fixation test (CFT) and the indirect fluorescent antibody test (IFAT) were conducted on weekly serum samples from nine Arab geldings for 28 days before and 256 days after their exposure to Babesia equi of European origin. On an average the IFAT became positive 8 days before the CFT and showed higher relative serum titer increases. Both test procedures successfully detected infection and neither showed an appreciable drop in titer during this time frame, with the exception of the CFT, which showed a transient drop immediately following treatment with imidocarb. A test conducted 540 days after infection showed four of the eight surviving, and presumably infected, horses to be negative on CFT, where as all eight were still positive on IFAT. Comparisons made with the IFAT, on horse sera from B. equi infection of both European and North American origin, utilizing homologous and heterologous antigens, showed significantly higher titers with homologous antigens.     

The application of the indirect fluorescent antibody test in research on heartwater

The preparation of the antigen, details of the reagents, the titration of the antispecies conjugates and the execution of the indirect fluorescent antibody test are described. The sensitivity and specificity of the test and its applicability to the detection of antibodies to Cowdria ruminantium are recorded. The test is both highly specific and sensitive and can be applied to a wide range of studies on heartwater, including epidemiology, determination of the C. ruminantium infection rate of Amblyomma ticks and the evaluation of immunization against heartwater. The test can also be used to detect antibodies to the heartwater agent in the sera of game.     

Development and persistence of Cowdria ruminantium specific antibodies following experimental infection of cattle, as detected by the indirect fluorescent antibody test.

Different breeds of cattle were experimentally infected with Palm River, a Zimbabwean isolate, or Ball-3, a South African isolate of Cowdria ruminantium, derived from tissue culture or tick or blood stabilates. C. ruminantium specific antibody responses were detected by an indirect fluorescent antibody test (IFAT) using C. ruminantium-infected bovine aortic endothelial (BAE) cell cultures as antigen. The first detection of antibodies to C. ruminantium generally coincided with the peak of the febrile reaction and the antibodies remained detectable for a period of 8-30 weeks in the Palm River infected group and 18-30 weeks in the Ball-3 infected group. Peak reciprocal antibody titres in both groups ranged from 64 to 2048 between 3 and 6 weeks post-infection. No apparent serological differences were observed among the various C. ruminantium isolates when tested in homologous and heterologous IFATs. Post-infection sera to Anaplasma marginale, Theileria parva parva, Babesia bigemina and Rickettsia conorii did not exhibit reactivity with the C. ruminantium antigen. These results indicate the possible use of C. ruminantium-infected cultures as antigen in IFATs to detect similar C. ruminantium-specific antibody responses in the field in clinically sick, recovered and carrier animals.     

The modification of fluorescent antibody virus neutralization (FAVN) test for the detection of antibodies to rabies virus

The fluorescent antibody virus neutralization test (FAVN) for the detection of antibodies against rabies virus was modified by using a monoclonal anti-rabies antibodies and peroxidase anti-mouse conjugate instead of a fluorescent anti-rabies conjugate. The results were read on an automatic multi-channel spectrophotometer. A total of 182 serum samples from dogs were tested by both the original and modified FAVN methods and the results were compared. Good correlation was found between the two tests. Practically, the modified FAVN test was quicker and could be used for a larger number of samples.     

Influence of medication on development of serum antibody to swine dysentery as detected with indirect fluorescent antibody method.

Serums from 119 swine exposed to swine dysentery inoculum, and medicated with various drugs, were tested for antibodies to the large spirochete, using the indirect fluorescent antibody test, and were compared in tests with known positive serums from 18 nonmedicated swine which had recovered naturally. An inverse relationship existed between the efficacy of the drug and the serum antibody titer (highest dilution of the serum producing immunofluorescence of large spirochetes). The more efficacious drugs or doses resulted in lesser development of serum antibody. Diarrhea usually seemed necessary for the development of serum antibody. With the less efficacious drugs, there were more days of diarrhea. Some swine had diarrhea but did not develop an antibody titer, and a few swine had a titer but did not develop diarrhea. Swine which developed a titer were more immune against reexposure with infective inoculum. The medicaments, especially those given at higher concentrations, seemed to resolve the diarrhea or prevent the development of diarrhea, occurrences which were necessary for the development of immunity.     

Use of the indirect fluorescent antibody test in the detection of bovine respiratory syncytial virus antibodies in bovine serum.

The indirect fluorescent antibody test was adapted for identifying bovine respiratory syncytial virus and its specific antibody, using goat turbinate (GTU) cells. The virus caused maximal cytopathic effects in GTU cells 4 to 8 days postinfection, but fluorescence was not readily detected during this period. Fluorescence was maximal in infected GTU cells at 24 to 36 hours postinfection, but could be detected 48 hours postinfection. Bovine serums (331) which had been submitted to the Oklahoma Animal Disease Diagnostic Laboratory were tested for antibodies to this virus, and 73.6% were found to be positive.     

Evaluation of the indirect fluorescent antibody test as a diagnostic tool for East Coast fever in eastern Zambia

Serological surveys using the schizont indirect fluorescence antibody test (IFAt) are routinely carried out to monitor the Theileria parva infection prevalence. The present study evaluates the diagnostic accuracy of the IFAt in eastern Zambia, where the transmission of T. parva is highly seasonal. The data set resulted from a sentinel herd (n = 105 animals) study carried out between 1995 and 2000 and was split into an epidemic period, during which the majority of the cattle became infected, and an endemic period with seasonal disease incidence in calves. In the epidemic period the T. parva seroprevalence followed closely the build up of the herd immunity. In the endemic period the seroprevalence fluctuates considerably although most of the animals had been infected. Overall, the diagnostic sensitivity of the IFA test was 55% at cut-off titre 1:40 and 28% at cut-off 1:160. The specificity of the test was 86 and 95%, respectively. A logistic regression model demonstrates that the sensitivity is significantly lower when the T. parva transmission is low (p < 0.01). The analysis of receiver operator characteristic curves classifies the test as moderately accurate (area under the curve, AUC = 0.79) during the epidemic period and less accurate in the endemic period (AUC = 0.63). Neonatal serology surveys yield a better estimate of the infection prevalence. The sensitivity of the neonatal test was 73% at cut-off titre 1:40 and 24% at cut-off 1:160.     

Evaluation of indirect fluorescent antibody test (IFAT) for the diagnosis and screening of lumpy skin disease using Bayesian method

The performance of indirect fluorescence antibody test (IFAT) for serological diagnosis and screening of lumpy skin disease (LSD) was evaluated using methods without gold standard. Virus neutralization test (VNT) was used as the second test and the study sites were selected from two different geographical places in Ethiopia to get different disease prevalence. The analysis of conditional dependent Bayesian model for the accuracy of IFAT showed that sensitivity, specificity, prevalence of the population Pi₁ and the population Pi₂ were 0.92 (0.89–0.95), 0.88 (0.85–0.91), 0.28 (0.25–0.32) and 0.06 (0.048–0.075), respectively. The posterior inferences obtained for VNT sensitivity, specificity and conditional correlation between the tests for sensitivity (rhoD) and specificity (rhoDc) were 0.78 (0.74–0.83), 0.97 (0.95–0.99), 0.052 (−0.03–0.15) and 0.019 (−0.01–0.06), respectively. The interval estimation of conditional correlation for both sensitivity and specificity clusters around zero and thus conditional dependence between the two tests was not significant. Although accuracy measure would not be the only basis for test selection, the result of our study demonstrated that IFAT has a reasonable high accuracy to be used for the diagnosis and sero-surveillance analysis of LSD in the target population.