An indirect fluorescent antibody test for antibodies to transmissible gastroenteritis of swine.

The indirect fluorescent antibody test was modified to provide a rapid technique for the detection, screening and titration of antibodies to transmissible gastroenteritis of pigs. Large numbers of slides containing transmissible gastroenteritis antigen were prepared by planting mixtures of infected and uninfected swine testicular cells onto multiwelled teflon-coated slides. After overnight incubation, about one-half of the cells in each well were infected which provided contrast to aid in detecting specific fluorescence in the presence of varying degrees of background staining. Following fixation, antigen slides were stored at -20 degrees C until used. The indirect fluorescent antibody test was compared to the virus neutralization test in both the screening and titration of swine sera containing transmissible gastroenteritis antibodies. The test was found to be sensitive and reliable and to offer certain advantages over the virus neutralization test.     

Application of a modified indirect fluorescent antibody test to the detection of antibodies to bovine respiratory syncytial virus in Ontario cattle.

A modified indirect fluorescent antibody test for the detection of serum antibodies to bovine respiratory syncytial virus was developed. The test made use of Terasaki plastic microtiter plates in which bovine respiratory syncytial virus (Saskatchewan strain) infected Georgia bovine kidney cells were grown and fixed in situ by a modified acetone fixation procedure. Evans blue dye was used as a counterstain to reduce nonspecific fluorescence. In a study of 986 field sera from a geographically broad cross-section of mature Ontario cattle, 95% of the samples were found to be positive at or above a 1:2 dilution. No seronegative regions, counties or herds were identified. When representative samples covering a range of indirect fluorescent antibody titers were further examined by a microtiter virus neutralization assay, a significant agreement was found between the two tests. Up to a fourfold decrease in titer was observed when antigen coated plates were stored at -70 degrees C for four months. The modified indirect fluorescent antibody test for bovine respiratory syncytial virus antibody detection proved to be a rapid, practical procedure for use in the diagnostic laboratory. This study confirms that bovine respiratory syncytial virus is widespread in the Ontario cattle population and that most mature cattle can be assumed to have been exposed to this virus.     

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.     

An indirect fluorescent antibody test for the detection of Cytauxzoon-like organisms in experimentally infected cats.

Antiserum to feline Cytauxzoon-like parasites was used in conjunction with labeled rabbit antisera to feline globulins to detect the presence of Cytauxzoon-like parasites in spleens of experimentally infected cats. Frozen spleen sections from 21 infected cats showed positively fluorescing masses within splenic veins and a diffuse scattering of discretely fluorescing cells in the red and white pulp. The distribution of fluorescence corresponded with the appearance of parasitized reticuloendothelial cells in histological preparations of spleen tissue. This indirect fluorescent antibody test consistently detected the presence of Cytauxzoon-like parasites in frozen spleen sections from experimentally infected cats.     

A modified immunoperoxidase assay for detection of antibody porcine reproductive and respiratory syndrome (PRRS) virus in swine sera

MARC-145 cell monolayers infected with PRRS virus were fixed in 3% neutral buffered formalin and embedded in paraffin. The sections were stained by avidin-biotin complex immunoperoxidase (ABC) method. Test sera were applied to sections as primary antibodies. The positive reactions were detected by ABC method and indirect immunofluorescent assay (IFA). There was good correlation between ABC and IFA, and the titers in ABC were higher than those in IFA. The present results indicate that the immunohistochemical staining is a useful test for the detection and quantitation of PRRS virus antibody in swine sera as well as IFA.     

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.     

Indirect solid-phase microradioimmunoassay for detection of pseudorabies virus antibody in swine sera.

An indirect solid-phase microradioimmunoassay (IRIA) was developed for detection and quantitation of antibodies to pseudorabies virus (PRV) in swine serum. Qualitative results of the IRIA compared closely with results of the serum neutralization test (NT) and the microimmunodiffusion test (MIDT). The IRIA was more sensitive than the NT for detection of antibodies to PRV in swine serum. The IRIA result is expressed numerically. With the IRIA and NT, antibody to PRV was first detectable in 3 experimentally infected pigs at 9 days after inoculation. With MIDT, antibody was detected in the 3 experimentally infected pigs at 9 days after inoculation. With the MIDT, antibody was detected in the 3 experimentally infected pigs at 7, 8, and 9 days after inoculation. The IRIA results are obtainable within a few hours; the NT and MIDT require 48 hours for completion.     

重组M蛋白间接ELISA检测猪繁殖与呼吸综合征病毒抗体

用纯化的猪繁殖与呼吸综合征病毒重组M蛋白作包被抗原,建立了检测猪繁殖与呼吸综合征病毒抗体的间接ELISA方法,并确立了ELISA最佳工作条件:抗原包被浓度为3.5μg/mL,37℃1h加4℃过夜,血清(1:40)和酶标SPA(1:80)分别在37℃温育1h,加底物溶液常温显色5min。经重复性试验、交叉试验、阻断试验等试验结果表明该方法重复性好、特异性强、敏感度高;与美国IDEXX公司试剂盒相比较,特异性和敏感性分别为96.3%和93.5%,无显著性差异。用建立的方法检测临床血清样品168份,总阳性率为39.9%。     

Enzyme-linked immunosorbent assay for detection of transmissible gastroenteritis virus antibody in swine sera

An enzyme-linked immunosorbent assay (ELISA) was developed for detection and quantification of serum antibodies to transmissible gastroenteritis virus (TGEV) in swine. Sera from pigs inoculated with cell culture-origin TGEV or gut-origin TGEV were tested for anti-TGEV antibody by ELISA and by serum virus-neutralization test (NT). The ELISA detected antibody 3 days (av) sooner than did the NT when sera from pigs inoculated with cell culture-origin TGEV were tested and 1 day sooner than did the NT when sera from pigs inoculated with gut-origin TGEV were tested. The ELISA appeared to be more sensitive than the NT, since ELISA was more responsive to low-level antibody and ELISA titers exceeded NT titers.     

Antigenic comparison of Lelystad virus and swine infertility and respiratory syndrome (SIRS) virus.

This study reports the antigenic relatedness of isolates of Lelystad virus collected in the Netherlands, Germany, and the United States. The binding of antibodies directed against these isolates was tested in a set of field sera collected during outbreaks of porcine epidemic abortion and respiratory syndrome in Europe and outbreaks of swine infertility and respiratory syndrome (SIRS) in North America. Two sets of sera from pigs experimentally infected with Lelystad virus or SIRS virus were also tested. Although all 7 isolates reacted with anti-Lelystad virus sera, antigenic variation was considerable. The 4 European isolates resembled each other closely, but differed from the American isolates, and the 3 American isolates differed antigenically from each other. To reliably diagnose Lelystad virus infection, a common antigen must first be identified.     

Immunofluorescence of spirochetes with serum from swine recovered from swine dysentery using an indirect fluorescent antibody test.

Using an indirect fluorescent antibody test, immunofluorescence of large spirochetes was observed with serum from swine that had recovered from swine dysentery. The spirochetes were obtained from scrapings of the colonic mucosa on the first day of diarrhea which was the time when the spirochete population was observed to be the highest. Of 29 exposed nonmedicated swine which developed and recovered from a diarrhea characteristic of swine dysentery 27 had antispirochete serum titers which ranged from 1:2 to 1:16. None of the 50 nonexposes swine developed a titer. Of 19 swine with a serum titer and reexposed with infective swine dysentery inoculum, 18 did not develop a diarrhea and were presumed to be immune. Considering these findings it is possible that this test could be used to detect antispirochete antibody in unknown swine serum.     

The indirect fluorescent antibody test for bovine anaplasmosis

Summary

An indirect fluorescent antibody test was used succesfully for the serodiagnosis of experimental Anaplasma infections in cattle. Specific antibodies were detected three to ten days after anaplasma bodies werd found in the blood, and persistedat least 15 weeks post‐infection.

An American and an African stock of A. marginale were used to prepare antigens, and gave comparable results when tested on sera positive to either of these stocks, as well as to an A. centrale‐like stock from Korea.

There were no cross‐reactions with several Theileria, Babesia, Trypanosoma and Eperythrozoon species.     

猪繁殖与呼吸综合征病毒重组N蛋白间接ELISA方法的建立

用纯化的猪繁殖与呼吸综合征病毒(PRRSV)重组核衣壳(N)蛋白作为包被抗原,建立了PRRSV抗体检测的间接ELISA方法,并优化确定了ELISA最佳工作条件:重组抗原包被浓度为13.3 μg/mL,37℃1h或4℃过夜;5％脱脂乳37℃封闭2h;血清1:40稀释,37℃作用90 min;酶标二抗1∶4000稀释,37...     

The fluorescent antibody and indirect fluorescent antibody assays for diagnosing stunting syndrome of turkeys

The fluorescent antibody (FA) assay was developed for detecting the stunting syndrome agent (SSA) from intestinal tissue. Similarly, the indirect fluorescent antibody (IFA) assay was developed for detecting serum antibodies to SSA. Convalescent antiserum from turkeys orally immunized with SSA was found to be the primary antibody of choice for the FA assay. Intestinal jejunal samples from poults inoculated 3-4 days postinoculation (DPI) was found to be the best antigen source for the IFA assay. SSA was detected from the intestinal tracts of experimentally inoculated birds at 2 DPI with highest level of reactivity at 3 DPI by the FA assay. After 4 DPI the level of SSA infectivity of the intestines waned to low levels. Serum antibody was detected from experimentally inoculated birds as early as 7 DPI with all birds tested seroconverting by 12 DPI. These assays should prove useful for future studies concerning stunting syndrome.     

重组N蛋白间接ELISA检测猪繁殖与呼吸综合征病毒抗体

用纯化的猪繁殖与呼吸综合征病毒重组N蛋白作为包被抗原，建立了检测猪繁殖与呼吸综合征病毒抗体的间接ELISA方法，并确定了ELISA最佳工作条件：抗原包被浓度为0．27μg/ml，37C1h加4C过夜，血清(1：40)和酶标免抗猪IgG(1：400)分别在37℃温育30min，底物溶液37℃显色15min。经重复性试验、交叉试验、阻断试验等试验结果表明该方法重复性好、特异性强、灵敏度高；与美国IDEXX试剂盒相比较，特异性和敏感性分别为97．6％和92．1％，无显著性差异。用已建立的方法检测临床血清样本187份，总阳性率为30．5％。