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P Nicoletti

Publications and source records attributed to P Nicoletti.

At least 73 records · Page 4Linked to original sources
PubMed1981

Prevalence and persistence of Brucella abortus strain 19 infections and prevalence of other biotypes in vaccinated adult dairy cattle.

The prevalence and persistence of Brucella abortus strain 19 shedding from the udder were studied in adult cattle in infected dairy herds that were vaccinated by 4 methods. Specimens were cultured from 1,736 cows in 55 vaccinated herds. Of the 744 brucella isolates, 98 were strain 19 and were from cattle in 25 of the herds. Shedding was highest among conjunctival vaccinates (1.4%) and higher in those given the standard subcutaneous dose (0.83%) than in those given a reduced subcutaneous dose (0.45%). Isolations were not made from intradermally vaccinated cattle. The persistence of strain 19 shedding was related to the length of time after the initial isolation. Approximately 20% of the shedders that remained in the herds were seropositive 13-18 months later. Cattle were selected for bacteriologic studies largely on positive results of rivanol or complement-fixation tests inasmuch as the card and tube agglutination tests were unreliable. Of the 646 field strain isolates, 95.8% were biotype 1, 2.5% were biotype 2, and 1.7% were biotype 4.

Animals↗
PubMed1981

Indirect hemolysis test in the serodiagnosis of bovine brucellosis.

An indirect hemolysis (IHL) test was compared with 4 other serologic procedures in sensitivity and specificity, using bacteriologic findings from cattle in Brucella-infected herds. The test was more sensitive than the complement-fixation and tube agglutination tests, was similar to the Rivanol test, and was slightly inferior to the card test. It was more specific than the Rivanol, card, and tube agglutination tests, but had less specificity than the complement-fixation test. Results of all procedures were affected in varying degrees by the method of vaccination and time period of sample collections after vaccination. Twenty vaccinated Brucella-free adult cattle were also studied, using the IHL and other tests. Only a few cattle that were previously vaccinated had reactions to the IHL test.

Agglutination Tests↗
PubMed1980

Evaluation of a radial immunodiffusion test with polysaccharide B antigen for diagnosis of bovine brucellosis.

A radial immunodiffusion (RID) test employing a polysaccharide antigen (poly B) was compared with tests currently used in the diagnosis of bovine brucellosis. Over 1,000 sera from vaccinated and infected cattle, all of which had been examined bacteriologically, were used to determine the sensitivity and specificity of the RID, card, Rivanol, and complement fixation tests. The RID test identified 90% of the cattle that were shedding Brucella in their milk. Although the complement fixation test was more sensitive, it was less specific than the RID test in cattle vaccinated as adults with Brucella abortus strain 19. A sensitive screening test, such as the card test, in combination with the RID test could be used in diagnostic laboratories, or even in the field, with little additional expense or technical expertise. An additional advantage is that the RID could be applied to sera from adult cattle as early as 2 months after vaccination, when postvaccinal agglutinins and complement-fixing antibodies may still be present. The indirect hemolytic test was used with some of the sera and was found to be a very sensitive test which could be useful in areas of low incidence but would not be practical for large-scale testing in adult-vaccinated herds.

Animals↗
PubMed1980

Studies on in vitro lymphocyte stimulation assay in cattle naturally infected with Brucella abortus and in cattle vaccinated with strain 19.

Cell-mediated immune responses of cattle in infected herds vaccinated with Brucella abortus, strain 19, and of nonexposed controls were studied by an in vitro lymphocyte stimulation test (LST). Brucella abortus soluble antigen was used as a specific stimulator of lymphocytes. Lymphocyte suspensions were prepared from peripheral blood of cattle by the Ficoll-diatrizoate technique. Cultures were labeled with [3H]thymidine and were assayed for [3H]thymidine incorporation into DNA by liquid scintillation spectrometry. Seroagglutination tests and cultures from Brucella were conducted simultaneously with LST. Brucella abortus soluble antigen induced significantly higher (P less than or equal to 0.005) lymphocyte stimulation responses in lymphocytes from cattle infected with B abortus than in lymphocytes from cattle vaccinated with strain 19 or from nonexposed controls. There was a significant P = agreement in results of LST and seroagglutination tests in infected cattle. Among seropositive-vaccinated cattle and controls, the LST was negative.

Animals↗
PubMed1979

Cell-mediated immune responses in cattle adult-vaccinated with Brucella abortus strain 19 and in cattle infected with Brucella abortus field strain.

Cell-mediated immune responses in cattle adult-vaccinated with Brucella abortus strain 19, cattle infected with B abortus field strain, and nonexposed cattle were studied by an in vitro lumphocyte-stimulation test (LST). Lymphocytes were prepared from peripheral bovine blood by the Ficoll-diatrizoate technique, and results were assayed for [3H]thymidine incorporation into DNA by liquid scintillation spectrometry. Serotests and bacteriologic isolation attempts were conducted simultaneously with LST. Lymphocytes from cattle infected with field strains had significantly (P = 0.01) higher specific lymphocyte-stimulation inexposed controls. The LST, the serum standard-tube agglutination test (STT), the Rivanol (RIV) test, and the complement-fixation (CF) test correctly classified cattle from which field strains and strain 19 of B abortus were isolated. The LST was negative in cattle vaccinated with B abortus strain 19 (nonshedding), but the three serotests had many false-positive reactions. The CF test had the least false-positive reaction, followed by the RIV test, and the STT was the least specific. Well before the three serotests became positive, the LST was positive in samples from some cattle during the incubation period of the infection. There was little or no correlation between cell-mediated immune responses (as measured by LST) and serum antibody responses (as measured by STT, RIV test, and CF test) in vaccinated but culture-negative cattle and in some nonvaccinated cattle during the incubation period.

Agglutination Tests↗
PubMed1978

Brucellosis in feral swine in Florida.

Serums from 95 feral swine trapped in Glades County, Florida, were tested for brucella antibodies, using the standard tube, card, rivanol, and complement-fixation tests. Fifty (53%) of the animals were seropositive to at least 1 test. The standard tube test detected 98% of the serums positive to any of the 4 procedures. The prevalence of brucella antibodies was significantly lower (P less than 0.0005) in feral swine less than 6 months old than in those greater than or equal to 6 months old. The prevalences by sex were similar. Necropsies were performed on 9 of the feral swine. Brucella suis, biotype 1, was recovered from all 9, with lymph nodes being the tissues most commonly infected. Only the standard tube test detected brucella antibodies in all 9 culture-positive animals.

Animals↗
PubMed1978

Whole-blood lymphocyte stimulation assay for measurement of cell-mediated immune responses in bovine brucellosis.

A study was conducted to develop an in vitro whole-blood lymphocyte stimulation assay for measurement of cell-mediated immune response in bovine brucellosis. A soluble antigen (BASA) prepared from killed cells of Brucella abortus 1119-3 was used. Cattle infected with B. abortus field strains, B. abortus 19 calfhood- and adult-vaccinated cattle, and nonexposed cattle were tested. Blood was diluted 10-fold in RPMI-1640 medium (without added serum) and cultured with BASA (at a concentration of 2.2 microgram per culture) at varying times of incubation. Results were assayed for [3H]thymidine incorporation into deoxyribonucleic acid. A 6-day period was found to be optimal for incubating blood cultures to achieve maximum specific lymphocyte stimulation. Serological tests and bacteriological isolation attempts were conducted simultaneously with lymphocyte stimulation tests, and there was a significant correlation between cell-mediated immune response and bacteriological findings. There was a significant correlation between cell-mediated immune response and the level of serum antibodies on a group basis, but there was little correlation between the two systems on individual infected animals. Among vaccinated animals there was little or no correlation between cell-mediated immune and humoral responses. The whole-blood assay was found to be simple, fast, sensitive, and reproducible.

Animals↗
PubMed1976

Problems in the diagnosis of bovine brucellosis.

In any disease eradication program, it is the unusual animal which assumes the greatest importance. There are no easy formulae for the diagnosis of brucellosis and many problems remain to be solved. A large variety of diagnostic methods has been studied and each has advantages and limitations. Simple agglutination tests will surely remain the basis for examinations of large numbers of sera and they should often be used only for screening. Selected supplemental tests are often necessary to confirm preliminary test findings. Any diagnostic procedure should not fail to correctly identify infected cattle and interpretations of results should not lead to excessive overcondemnation. Serologic methods must always be evaluated through bacteriologic attempts. There is no substitute for expertise to constantly study disease patterns in individual cattle and herds.

Age Factors↗