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1.
Corynebacterium pseudotuberculosis is the cause of caseous lymphadenitis (CLA) in small ruminants, a chronic granulomatous disease that provokes significant zootechnics losses to ovine and goat breeders in northern Brazil. The present work was conducted to analyse aspects of humoral and cellular immune responses after experimental infection. Eight goats were infected intradermally with a single dose of virulent C. pseudotuberculosis strain and specific IgG, interferon-gamma (IFN-gamma) production as well as IgG avidity and antigens pattern recognition dynamics against an excreted-secreted antigen were recorded during 20 weeks. At the end of the follow-up, animals were slaughtered and necropsied. Although no animals showed apparent clinical signs of infection at the end of the trial, IFN-gamma response, even more so than the humoral response, differentiated animals into two groups of high or medium/low response. The time-course of IFN-gamma production presented a short-lived primary response on day 5 after infection of animals of both groups, and a strong and long lasting secondary response starting on day 16 after infection in the high response group. The indirect ELISA used was able to detect a positive antibody titre between 6 and 11 days after infection in the two groups. IgG avidity index oscillated initially between 15 and 45%, and showed approximately 5% units increment during the 20 follow-up weeks. With only one individual exception, the qualitative antigens pattern recognition showed on day 11 after infection remained constant through the experiment. IgG avidity is highly correlated with IgG production, but could not be related with specific immunodominant bands. Both humoral and cellular responses kinetics presented a similar pattern of activation/deactivation but necropsy results suggested that the IFN-gamma test would be a very specific marker of CLA status.  相似文献   

2.
Canine brucellosis is a reportable zoonotic disease that can lead to canine reproductive losses and human infection through contact with infected urine or other genitourinary secretions. Although many locations require testing and euthanasia of positive dogs, current diagnosis is limited by the time required for seroconversion, for example, presence of B. canis‐specific antibodies. The goal of this study was to determine the diagnostic ability of Brucella canis‐specific quantitative polymerase chain reaction (qPCR) assay to detect B. canis in field samples prior to serological positivity for faster diagnosis and prevention of transmission within kennels or in households. Two kennels, one of which was located in the owner's home, were sampled following observation of suggestive clinical signs and positive serology of at least one dog. Specimens obtained were comparatively analysed via serology and qPCR analysis. 107 dogs were analysed for B. canis infection via qPCR: 105 via whole‐blood samples, 65 via vaginal swab, six via urine and seven via genitourinary tract tissue taken at necropsy. Forty‐five dogs were found to be infected with canine brucellosis via qPCR, of which 22 (48.89%) were seropositive. A statistically significant number (P = 0.0228) of qPCR‐positive dogs, 5/25 (20.00%), seroconverted within a 30‐day interval after initial serologic testing. As compared to serology, qPCR analysis of DNA from vaginal swabs had a sensitivity of 92.31% and specificity of 51.92%, and qPCR analysis of DNA from whole‐blood samples had a sensitivity of 16.67% and specificity of 100%. B. canis outer membrane protein 25 DNA qPCR from non‐invasive vaginal swab and urine samples provided early detection of B. canis infection in dogs prior to detection of antibodies. This assay provides a critical tool to decrease zoonotic spread of canine brucellosis, its associated clinical presentation(s), and emotional and economic repercussions.  相似文献   

3.
Recently a commercial enzyme-linked immunosorbent assay (ELISA) kit for detecting antibody against H1N1 swine influenza virus (SIV) has been made available to diagnosticians and veterinary practitioners. Because the hemagglutination inhibition (HI) test has been considered the standard test for SIV serology, diagnostic performance of the new ELISA was evaluated using positive (n = 60) and negative (n = 188) serum samples from young pigs with known status of SIV infection and compared with that of the HI test. Both ELISA and HI test identified all negative animals correctly. None of the serum samples (n = 64) from pigs inoculated with H3N2 SIV was positive by ELISA for SIV antibody. The H1N1 SIV antibody detectable by ELISA appears to develop more slowly in comparison with antibody detectable by HI test. Although antibody was detected by HI test in all inoculated animals (n = 20) by day 7 postinoculation (PI), antibody was detected by ELISA in 0%, 75%, and 100% of the inoculated animals on days 7, 14, and 28 PI, respectively. Discrepancy in test results between the 2 serologic tests appeared to be because of differences in antibody isotypes detected by each test. Enzyme-linked immunosorbent assay mainly detected IgG antibody, whereas the HI test detects IgM antibody very efficiently as well as IgG antibody. Collectively, the commercial ELISA is highly specific for antibody to H1N1 SIV but may not identify positive animals at the early stage of infection as effectively as the HI test, particularly when SIV is introduced to a na?ve swine population.  相似文献   

4.
Background: The performance of Giardia diagnostic tests that detect either cysts or fecal antigens has not been thoroughly examined. Hypothesis/Objectives: We examined the concordance and agreement among 4 Giardia diagnostic tests (2 cyst and 2 coproantigen detection methods) in a colony of dogs chronically and subclinically infected with Giardia. Animals: Twenty dogs with chronic, subclinical Giardia infection. Methods: Giardia diagnostic tests were performed repeatedly on each dog over 120 days. Fecal cyst detection methods (ZnSO4 flotation and fluorescent antibody [FAB] coproscopy) were performed 3 times per week. Coproantigen methods (Giardia SNAP test and quantitative ELISA) were performed weekly. Results were analyzed and compared among methods. Results: When compared with FAB coproscopy, all of the in‐house diagnostic tests had excellent positive predictive values (PPVs, 95–99%) at the study prevalence (89%). At lower prevalence rates, ZnSO4, SNAP, and ELISA tests all had good negative predictive values (NPVs), but poor PPVs. There was poor to good agreement among tests by κ analysis. Conclusion and Clinical Relevance: Our findings show that most commonly used in‐house Giardia diagnostic tests have poor agreement with the gold standard method (FAB coproscopy). The in‐house tests have good NPVs, but poor PPVs, at prevalence rates common in most clinical settings.  相似文献   

5.
An experimental reproduction of CBPP was implemented and the animals were surveyed for serology during 4 months. The ELISA/IgG test detects the antibodies few days after the CF test but is more precise for detection on the longer term. The early antibody detection can be done with the ELISA/IgM test. Circulating antigen (galactan) has been detected in a cow that died of an acute form of CBPP. Excretion of mycoplasmas starts 1 to 2 weeks before the seroconversion: the ELISA/IgG test remains positive during the excretion phase and even longer.  相似文献   

6.
The dot-ELISA reaction was used to study the dynamics of IgG titers in cattle naturally infected with Fasciola hepatica after anthelmintic treatment and during reinfection. Excretion/secretion products (ES) of the parasite were used as antigens for the dot-ELISA. IgG antibodies were no longer detectable by dot-ELISA, 4-6 months after nine animals received the first of three weekly doses of triclabendazole (15 mg kg(-1)) and were then maintained on a pasture free of F. hepatica metacercariae. Six fluke-free cattle began shedding F. hepatica eggs 3-6 months after grazing a pasture contaminated with metacercariae of the parasite. A detectable increase in dot-ELISA IgG antibody levels was observed 2-4 weeks after natural reinfection by grazing a similar pasture contaminated with F. hepatica metacercariae. The usefulness of the dot-ELISA system to diagnose chronic infection by serology is complicated by previous treatment against the parasite. It is concluded that the ES antigens can be useful to detect early infection of cattle with F. hepatica in a dot-ELISA system  相似文献   

7.
Cyst-forming coccidia may cause significant losses in livestock, primarily due to abortion, loss of young animals and neuromuscular diseases. Rather recently, Neospora caninum has been recognized as one of the major protozoal abortion-inducing parasites in cattle. The present study addressed the performance of different diagnostic tools (in vitro-cultivation; histology; immunohistochemistry; serology; PCR) suitable for the direct or indirect detection of N. caninum. By PCR, Neospora-DNA was detected in 24 brains (29%) from 83 bovine abortion, many of these brains were simultaneously characterized by histopathological findings typical for a protozoal, cerebral parasitosis. The diagnostic methods were furthermore assessed using samples of different tissues and body fluids from three experimentally Neospora-infected pregnant cows and their foetuses. The diaplacental passage of N. caninum to the foetus was successful in two of the three cases. In these two cases, PCR was positive for different foetal organs and, additionally, for the abomasal and amniotic fluid. The successfully infected cows developed anti-Neospora serum antibodies between 10 and 17 days post infection, foetuses remained serologically negative in all cases. The results obtained in the present study demonstrated the usefulness of PCR, complemented by serology, for the specific diagnosis of bovine neosporosis. Such tests may prove suitable to perform epidemiological investigations. Taken together, our data indicated that prenatal neosporosis may be an important cause of infectious bovine abortion in Switzerland.  相似文献   

8.
Goats housed in microbiologically secure facilities were experimentally endobronchially infected with Mycoplasma capricolum subsp. capripneumoniae (Mccp), causal agent of contagious caprine pleuropneumonia (CCPP). The animals were monitored over an 8-week period post-infection (p.i.). Elevated temperatures were observed 2-7 days p.i., reaching a maximum of 41.5 degrees C in one animal (1884). By 8 weeks p.i. the infection was successfully cleared, with no Mccp being recovered from the lungs, serum or nasal passages. Mccp was not isolated from serum throughout the experiment, either directly by culture or indirectly via polymerase chain reaction (PCR). Humoral immune responses against Mccp capsular polysaccharide (CPS) were generally poor when measured by ELISA. CPS antigen was present in the serum of all infected animals early in the infection (day 14 p.i.), although in one animal (1855) CPS antigen persisted throughout. This was the only animal to exhibit a serious cough (day 5-19 p.i.). Successful diagnosis of CCPP was achieved using two different types of latex agglutination test (CPS antibody and CPS antigen detection test), immunoblotting and a blocking ELISA, although the latter lacked sensitivity until later in the infection (35-40 days p.i.). Only a single animal (1855) was detected positive using the current complement fixation test (CFT). Strong immune responses to protein antigens were detected by IgG and IgM immunoblotting from the first time point at day 14 p.i. IgM immunodominant bands of 220, 85, 62 and 40kDa were observed in the 3 infected animals and from CFT-positive CCPP field sera. Band intensity gradually diminished throughout the experiment. IgG immunodominant bands of 108, 70, 62, 44, 40 and 23kDa were shared between experimentally-infected and field sera, with band intensity either remaining unchanged or increasing from day 14 p.i. These bands were not present using pre-infection sera. Of the diagnostic tests used, only the CPS antibody detection latex agglutination test and IgG immunoblotting gave positive diagnoses throughout the entire period post-infection (days 14-53 p.i.).  相似文献   

9.
Abomasal cannulation followed by serial collection of biopsies was used to study the kinetics of appearance of IgA-, IgG1-, IgG2- and IgM-containing cells in the abomasum of sheep following infection with Haemonchus contortus. Very few immunoglobulin-containing cells (ICC) were found in the abomasum of sheep before infection. Following H. contortus infection, there were increased numbers of ICC in the submucosa of the abomasum. Seven days after infection, the numbers of IgA-, IgG1- and IgM-containing cells were six times greater than for uninfected control animals. The numbers of ICC continued to rise as the infection progressed, and the peak response was observed between 21 and 28 days after infection. IgA-containing cells (68-84%) were the most frequent cell types at all the observation times, followed by IgG1 and IgM. IgG2-containing cells were minimal throughout the experiment. As there were no significant changes in the numbers of ICC in the abomasum of uninfected controls it is concluded that H. contortus stimulated a local immune response in the abomasum of parasitized sheep.  相似文献   

10.
Over the last few years, several cases of feline leishmaniasis (FL) with cutaneous and visceral forms have been reported around the world. Nonetheless, the real susceptibility of cats to infection with Leishmania spp. and the outcome of leishmaniasis in these animals are poorly understood. Experimental studies on feline models will contribute to the knowledge of natural FL. Thus, in order to determine the susceptibility of domestic cats (Felis catus) to experimental infection with Leishmania braziliensis, 13 stray cats were infected with 10(7) promastigotes by the intradermal route in the ear and nose simultaneously and followed up for 72 weeks. Soon after infection, the earliest indication of a lesion was a papule on the ear at 2 weeks post-infection (w.p.i.). The emergence of satellite papules around the primary lesion was observed about 4 w.p.i. Two weeks later these papules coalesced and formed a huge and irregular nodule. Thereafter, there was lesion dissemination to the external and marginal surface of the ipsilateral ear, and later to the contralateral ear. At 10 w.p.i., some nodules became ulcerated. Nose lesions presented a similar evolution. At both sites, the largest lesion sizes occurred at 10 w.p.i. and started to decrease 15 days later. Ear and nose nodules healed at 32 and 40 w.p.i., respectively. Specific L. braziliensis IgG antibody titers (optical density> or = 0.01 as positive result) were detected as early as 2 w.p.i. (0.09 +/- 0.02) in only three animals (23%), and all cats had positive titers at 20 w.p.i. (0.34 +/- 0.06). Only three animals (38%) continued to show positive serology at 72 w.p.i. (0.08 +/- 0.02). Up to that time, none of the cats had lesion recurrence. In a feline model of cutaneous leishmaniasis, it seems that there is no correlation between active lesions and positive serology. The implications of these data are discussed.  相似文献   

11.
Molecular analysis, serology and immunophenotyping for T lymphocytes and their subsets, B lymphocytes and monocytes were performed on dogs naturally infected with Leishmania infantum. Animals were categorised as asymptomatic dogs I (AD-I), with negative serology and positive molecular results, and asymptomatic dogs II (AD-II), with positive serology and positive molecular results, and these were compared to symptomatic dogs (SD) and control dogs (CD). AD-I exhibited immunophenotypic features similar to those of CD, including isotype profiles and concentrations of monocytes. Similar biomarkers were found in AD-II and SD, such as, higher levels of immunoglobulins IgG, IgG2, IgM and IgA and higher concentrations of eosinophils. High frequencies of T lymphocytes and CD4(+) T cells were observed in both AD-I and AD-II compared to SD, whereas CD8(+) T cells were higher only in AD-II compared with SD. Analysis of B lymphocytes revealed an increased frequency of this cell type only in AD-II animals compared with SD. Asymptomatic dogs appear to have a dichotomous infection spectrum that can influence the humoral and cellular immunological status during canine visceral leishmaniasis.  相似文献   

12.
Hilar lymphadenopathy is a common radiographic finding in coccidioides infections. Serologic studies are used most often for the diagnosis of coccidioidomycosis in endemic areas, with IgG titers ≥1:8 considered positive for infection and lower IgG titers of <1:8 considered indicative of exposure and not necessarily related to organism presence. The objective of this study was to determine the relationship of hilar lymphadenopathy to coccidioidomycosis titers for dogs in an endemic area. A positive association between these parameters would allow treatment to be initiated before obtaining titer results. Thoracic radiographs of 131 dogs from an endemic area were reviewed for evidence of hilar lymphadenopathy. These results were compared with serology results. There was a significant association between hilar lymphadenopathy and a positive serology result (P<0.001). With hilar lymphadenopathy as a predictor of a positive titer result, sensitivity was 28.0%, specificity was 91.5%, the positive predictive value was 43.8%; and the negative predictive value was 84.4%. There was no association between the titer result and gender, age, or weight. The radiographic finding of hilar lymphadenopathy appears to be a useful indicator of coccidioidomycosis infection in an endemic population of dogs supporting the treatment of patients for coccidioidomycosis when hilar lymphadenopathy is present and before obtaining serology results.  相似文献   

13.
Experimentally infected sheep have been previously developed as an animal model of trypanosomosis. We used this model to test the efficacy of megazol on eleven Trypanosoma brucei brucei-infected sheep. When parasites were found in blood on day 11 post-infection, megazol was orally administered at a single dose of 40 or 80mg/kg. After a transient aparasitaemic period, all animals except two relapsed starting at day 2 post-treatment, which were considerated as cured on day 150 post-treatment and showed no relapse after a follow-up period of 270 days. In order to understand the high failure of megazol treatment to cure animals, a kinetic study was carried out. Plasma concentrations of megazol determined, by reverse-phase high-performance liquid chromatography at 8h post-treatment in these animals, were lowered, suggesting slow megazol absorption, except in cured animals. However, megazol plasma profiles in uninfected sheep after a single oral dose of megazol showed a fast megazol lowered absorption associated with a short plasma half-life of drug. Inter-individual variation of megazol pharmacokinetic properties was also observed. These findings suggested that the high failure rates of megazol treatment were related to poor drug availability after oral administration in sheep. In conclusion, megazol could cure sheep with T. b. brucei infection but oral administration was not an effective route.  相似文献   

14.
In this study 595 lactating cows originating from 31 carinthian farms were investigated in accordance of liver fluke infection using individual and tank milk as well as individual blood and faecal samples. Two commercial ELISAs were used to test the milk and blood serum, and the results were compared with coproscopy and a commercial copro-antigen ELISA. Receiver operating characteristics (ROC) and two-graph operating characteristics (TG ROC) of tank milk results were conducted based on the individual milk to determine the minimum reliable in-herd antibody prevalence for the predominant condition in the investigation area. In 17.8% of the examined individuals located in 64.5% of the farms eggs were detected by coproscopy. The copro-antigen ELISA delivered 13.4% positive individuals from 54.8% of the farms. The milk ELISAs showed 42.7% (Euroclone) and 44.2% (Pourquier) positive cows on 90.3% of the farms. The blood samples were positive in 43% (Euroclone) and 45.2% (Pourquier) of the individuals from 90.3% to 96.8% of the herds, respectively. Based on the milk and the blood an average in-herd prevalence of 30-45% can be assumed. The serum and milk samples delivered correlating results with kappa values between 0.94 and 0.97, whereas the coproscopy and copro-antigen ELISA did not correlate well with the ELISA results. The two different ELISA tests highly correlated on individual and on herd level. Both showed a reliable minimum in-herd prevalence of ～20%, meaning that one fifth of the individuals in a herd have to be positive to obtain a positive bulk tank milk result. In the investigated area a higher in-herd prevalence is expected, therefore the tank milk is useful as a monitoring tool and can be used as a basis for intervention strategies.  相似文献   

15.
Equine clinical larval cyathostominosis is caused by simultaneous mass emergence of previously inhibited larvae from the mucosa of the colon. Clinical signs include diarrhoea, colic, weight loss and malaise, and in up to 50% of cases, the disease results in death. Cyathostominae spend a large part of their life cycle as larval stages in the intestinal mucosa. Definitive diagnosis is difficult due to the lack of diagnostic methods for pre-patent infection. In the present study, the enzyme-linked immunosorbent assay (ELISA) was used to investigate isotype responses to larval cyathostominae somatic antigen. Measurement of anti-larval IgG(T) responses appeared to have the most immunodiagnostic potential. An increase in IgG(T) response was detected to crude larval antigen by 5 weeks post-infection (PI) in individual infected ponies. Subsequently, IgG(T) responses to larval and adult somatic extracts were examined by Western blotting using sera from experimentally-infected horses and helminth-naive animals (n=6). Two antigen complexes, designated A and B, in larval somatic antigen were recognised specifically by the infected animals by 7 weeks PI. Sera taken from 23 endemically-infected animals, whose cyathostominae burdens had been enumerated, were also used to identify putative diagnostic antigens. Eighteen horses had positive mucosal worm burdens (range 723-3,595,725) and all but two of these animals had serum IgG(T) antibody specific to either complex. Moreover, IgG(T) responses specific to antigen complexes A and B were absent in all five parasite negative horses that were tested. Serum IgG(T) responses to either of the two complexes were identified in five clinical cases tested. IgG(T) responses to adult antigen somatic extracts were more heterogeneous, with no clear pattern between experimentally-infected ponies and helminth-free controls. The results indicate that increases in serum IgG(T) to mucosal larvae occur in the pre-patent period and that two antigenic complexes within somatic preparations of these stages have immunodiagnostic potential.  相似文献   

16.
The dynamics of the humoral immune response of calves were analysed after primary infection and re-infection with the intestinal nematode Cooperia punctata. 12 male 5 month-old Holstein-Friesian calves were randomly divided into two groups A and B. At the beginning of the experiment Group A animals were each infected experimentally with a single oral dose of 130,000 infective third stage larvae (L3) of C. punctata. The animals of Group B were kept as non-infected controls. The two calves from Group A with the highest infections died of cooperiosis at 32 and 44 days after infection (DAI), respectively. On DAI 100 the calves were treated with the recommended dose of oxfendazole. On DAI 180 the remaining four calves of Group A and three animals of Group B (B1) were infected with 260,000 L3 of C. punctata, while the other three calves of Group B (B2) served as non-infected controls. Monitoring of the humoral immune response predominantly demonstrated an IgG1 response against both adult and L3 antigen of C. punctata. Moreover, re-infections increased the levels of these immunoglobulins. IgA levels were less increased than IgG1 and no significant increase was observed in IgG2 and IgM levels. Immunoblotting analysis showed that total IgG present in the serum of the primary infected animals mainly reacted against adult proteins of 12-14 and 17-20 kDa and against L3 proteins of 33 and 43 kDa. After re-infection total IgG reacted with the same adult proteins but also with an adult 29 kDa protein.  相似文献   

17.
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18.
Data combining sequential bacteriology and serology from a longitudinal study of a dairy herd were used to demonstrate the limitations of serology as a diagnostic method in cross-sectional sampling of bovine populations. Whole-herd point serological prevalences showed considerable variation over a two-year sampling period (38.8 to 76.2 per cent), and this was mainly due to varying age-specific prevalence. Owing to the rapid decline in titres and the varying persistence of infection, point serological prevalences failed to approximate to cumulative infection rates (either past or present) at different times of the year. A higher estimate of the number of susceptible animals in the herd than is the case results in inaccurate information on true incidence rates and can confuse assessments of the susceptibility of different age groups, especially if only small numbers are sampled. A sampling exercise demonstrated that a 10-cow sample usually provided little useful information other than establishing the presence or absence of hardjo in the herd. Increasing the sample size markedly improved epidemiological information, investigations of clinical disease, assessments of vaccination needs and public health tracebacks. Preferably 10 sera from each of the yearling, first calver, second calver and older age groups should be tested. Serology was an inadequate indicator of infection in individual animals. Group geometric mean titres taken from a mean serological response curve were shown to have limited application in the interpretation of field data, unless infection had occurred in the previous two months.  相似文献   

19.
Two serological tests (indirect immunofluorescence and enzyme-linked immunosorbent assay) were developed for the detection of fetal antibody to Chlamydia psittaci. Fetal blood and thoracic fluid from 126 field cases of suspected ovine chlamydial abortion were examined using both tests. Placenta and fetal tissues (lung, liver, and kidney) from the same animals were also examined by the following conventional diagnostic methods: isolation in McCoy cells, detection of chlamydial lipopolysaccharide (LPS), modified Ziehl-Nielsen staining, and direct fluorescent antibody staining of chlamydia in frozen cryostat sections. Seventy cases were positive by fetal serology, and of these, 68 were also positive by isolation and/or LPS detection. The remaining 56 cases had negative fetal serology, and of these, 39 were positive by isolation and/or LPS detection. Results indicate that fetal serology, although less sensitive than either isolation in McCoy cells or detection of chlamydial LPS antigen, may be of particular use when placenta is not available.  相似文献   

20.
A Q fever epidemic occurred in 2013 in a small military residential area in Cayenne, French Guiana. A retrospective cohort study was conducted to identify Q fever risk factors. Confirmed acute Q fever case was defined as positive serology (IgM ≥ 50 and phase II IgG ≥ 200) and/or positive qPCR on serum or blood. In addition, wild mammals were captured at the study site and tested by serology and real-time PCR performed on blood, vaginal swabs and ticks. The attack rate was 20 percent (11/54). All the cases were symptomatic with fever >38.5 °C and community-acquired pneumonia for four cases. Log binomial multivariate models identified two independent risk factors associated with Q fever: to clean the house (RRa = 7.5 CI95% [1.03–55.3]) and to carry a three-toed sloth in arms (RRa = 2.6 CI95% [1.1–5.8]). Eighteen marsupial individuals were captured, all PCRs were negative but 17% (3/18) had a positive serology. Another study conducted after the epidemic found only one (1/4) three-tooth sloth (Bradypus tridactylus) with feces highly infectious for C. burnetii MST17. The same strain C. burnetii genotype 17 has been laboratory- confirmed in this mammal and in human cases. These results support the implication of three-toed-sloth in this epidemic. Human contamination mainly occurs through inhalation of infectious aerosols as suggested by high relative risk associated with house cleaning activities and pulmonary forms of the disease, and through direct contact with three- toed-sloth. Positive serological results among marsupials confirm wildlife exposure and suggest a more complex sylvatic transmission cycle among wild mammals.  相似文献   

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