Non-specific seroreactions against Brucella abortus in ruminants in New Zealand and the presence of Yersinia enterocolitica 0:9

The level of non-specific reactions found in the brucellosis serology of ruminants in New Zealand was very low until July 1992. This changed when, in an export consignment of 1071 deer, 35% reacted in the Brucella abortus tube agglutination test with titres varying from 50 to 200 IU. The reactors were also positive in the Rose-Bengal agglutination test and most of them reacted in the complement fixation test with titres varying from 10 to 80 IU. Yersinia enterocolitica 0:9 was later isolated from one deer of this consignment. It was the first isolate of this serotype recovered in New Zealand from an animal. Shortly after, false reactors occurred more frequently than before in sera from Brucella abortus accredited free cattle herds. As the involvement of Yersinia enterocolitica 0:9 was suspected in these cases, faecal samples from reactors and in-contact animals were cultured for this organism. Yersinia enterocolitica 0:9 was isolated from nine of 19 herds showing one or more false Brucella abortus seroreactions. Prior to 1990, Yersinia enterocolitica serotype 0:9 had not been isolated in New Zealand, despite the recovery of a number of other bio- or serotypes of the organism from humans and animals. From 1990 onward, serotype 0:9 began to be isolated from human faecal samples with increasing frequency. Since the first isolations from deer and cattle in 1992, it has now also been recovered from a cat and an alpaca and from cattle without any association with false positive Brucella abortus reactions. All serotype 0:9 isolates were of biotype 2.     

Detection of carriers of foot-and-mouth disease virus among vaccinated cattle

To investigate and optimise detection of carriers, we vaccinated 15 calves with an inactivated vaccine based on foot-and-mouth disease virus (FMDV) A Turkey strain and challenged them and two further non-vaccinated calves with the homologous virus four weeks later. To determine transmission to a sensitive animal, we put a sentinel calf among the infected cattle from 60 days post-infection until the end of the experiment at 609 days post-infection. Samples were tested for the presence of FMDV, viral genome, specific IgA antibodies, antibodies against FMDV non-structural (NS) proteins or neutralising antibodies. Virus and viral genome was intermittently isolated from probang samples and the number of isolations decreased over time. During the first 100 days significantly more samples were positive by RT-PCR than by virus isolation (VI), whereas, late after infection more samples were positive by virus isolation. All the inoculated cattle developed high titres of neutralising antibodies that remained high during the entire experiment. An IgA antibody response was intermittently detected in the oropharyngeal fluid of 14 of the 17 calves, while all of them developed detectable levels of antibodies to NS proteins of FMDV in serum, which declined slowly beyond 34 days post-infection. Nevertheless, at 609 days after inoculation, 10 cattle (60%) were still positive by NS ELISA. Of the 17 cattle in our experiment, 16 became carriers. Despite frequent reallocation between a different pair of infected cattle no transmission to the sentinel calf occurred. It remained negative in all assays during the entire experiment. The results of this experiment show that the NS ELISA is currently the most sensitive method to detect carriers in a vaccinated cattle population.     

Single dilution ELISA for detection of serum antibody to foot-and-mouth disease virus in cattle

A single dilution blocking ELISA was developed and evaluated for measuring serum antibody to foot-and-mouth disease virus (FMDV). Basic parameters of the assay were established and a positive-negative threshold determined from testing 176 specific antibody negative sera from Australian cattle. Sera collected from immunised animals in Thailand were tested by ELISA and virus-neutralisation (VN) tests and the results compared. A positive correlation between ELISA and VN titres was recorded for each of the 3 FMDV serotypes endemic in Thailand, with the overall correlation coefficient being r = 0.8990. A positive correlation for each of the serotypes was also found between ELISA titre and the degree of blocking (percentage inhibition) of each test serum at a dilution of 1:16, with the overall correlation being r = 0.8704. This simplified ELISA was sensitive, specific and gave reproducible results, and had the potential to test quickly and efficiently a considerable number of sera.     

Non-specific seroreactions against Brucella abortus in ruminants in New Zealand and the presence of Yersinia enterocolitica 0:9

The level of non-specific reactions found in the brucellosis serology of ruminants in New Zealand was very low until July 1992. This changed when, in an export consignment of 1071 deer, 35% reacted in the Brucella abortus tube agglutination test with titres varying from 50 to 200 IU. The reactors were also positive in the Rose-Bengal agglutination test and most of them reacted in the complement fixation test with titres varying from 10 to 80 IU. Yersinia enterocolitica 0:9 was later isolated from one deer of this consignment. It was the first isolate of this serotype recovered in New Zealand from an animal. Shortly after, false reactors occurred more frequently than before in sera from Brucella abortus accredited free cattle herds. As the involvement of Yersinia enterocolitica 0:9 was suspected in these cases, faecal samples from reactors and in-contact animals were cultured for this organism. Yersinia enterocolitica 0:9 was isolated from nine of 19 herds showing one or more false Brucella abortus seroreactions.

Prior to 1990, Yersinia enterocolitica serotype 0:9 had not been isolated in New Zealand, despite the recovery of a number of other bio— or serotypes of the organism from humans and animals. From 1990 onward, serotype 0:9 began to be isolated from human faecal samples with increasing frequency. Since the first isolations from deer and cattle in 1992, it has now also been recovered from a cat and an alpaca and from cattle without any association with false positive Brucella abortus reactions. All serotype 0:9 isolates were of biotype 2.     

Saponin Adjuvants. IV. Evaluation of The Adjuvant Quil a in the Vaccination of Cattle Against Foot-And-Mouth Disease

The saponin adjuvant Quil A has been investigated in the vaccination of cattle against foot-and-mouth disease. Using a Frenkel type vaccine a dose-response relationship has been established between Quil A and neutralizing antibody titres. Ten ml of vaccine was combined with 0, 50, 200, 800, and 3200 µg of Quil A. The combinations were each injected into 4 animals. The local reaction on the site of injection produced by injection of the vaccine alone and in combination with different doses of Quil A has been estimated. On this basis a therapeutical dose at 1 mg of Quil A has been estimated to combine maximum adjuvant effect with a minimum of adverse reactions. This dose has been tested in the vaccination of cattle with FMD vaccines derived from BHK suspension cell virus of type O and A respectively. The vaccines were tested in 10 ml and 5 ml doses with or without Quil A, and each in 4 animals. It is concluded that Quil A is a valuable adjuvant for use in the induction of neutralizing antibodies against foot-and-mouth disease in cattle.     

Assessment using ELISA of the herd immunity levels induced in cattle by foot-and-mouth disease oil vaccines

The development of a liquid-phase blocking sandwich ELISA (LPBE) to measure antibodies (Ab) produced in cattle with the O, A and C foot-and-mouth disease virus (FMDV) types of commercial vaccines used in Argentina is described. The test was specific: 99% of naïve cattle sera (n = 130) gave titres below log₁₀ = 1.2, and none had a titre above log₁₀ = 1.5. Comparative studies with serum neutralization test (SNT) using sera from cattle which received one or more vaccine doses is reported. The overall rank correlation coefficient (Spearman's , r_s) between SNT and LPBE were highly significant (r_s > 0.67, P < 0.0001) for all vaccine strains. LBPE Ab titres on sera collected 90 days post vaccination were compared with results of cattle protection tests by applying a logistic regression. The minimum Ab titres at which 85% and 75% of the cattle were protected for each FMDV type were determined in order to interpret field Ab data in terms of protection. Application of this method allows large scale serological examinations to monitor antibody levels in vaccinated animals as an indirect indicator of the FMD control program status in the field. Its use in the evaluation of commercial batches of FMD vaccine is discussed.     

Serological studies on bovine besnoitiosis in Israel

Sera from 1,700 beef and dairy cattle in Israel were tested for besnoitiosis by indirect immunofluorescence. Over 90% of dairy animals were negative whereas about 50% of beef cattle were positive. Among beef bulls the percentage of positive reactors increased with age but in beef cows the pattern was less clear; 36% of young imported bulls negative upon arrival developed antibody titres after one season on the range. Cross-tests with Toxoplasma gondii antiserum and antigen indicated that the results of the survey for besnoitiosis were unlikely to have been influenced by Toxoplasma antibodies.     

A complex-trapping-blocking (CTB) ELISA, using monoclonal antibodies and detecting specifically antibodies directed against foot-and-mouth disease types A, O and C. II. Application

The complex-trapping-blocking (CTB) enzyme-linked immunosorbent assay (ELISA) was evaluated to detect antibodies directed against foot-and-mouth disease virus (FMDV) strains A10 Holland, O1 BFS, and C1 Detmold. Log10 serum titres of uninfected, unvaccinated cattle (n = 100) were less than 1.80 in the CTB-ELISA. Sera from cattle vaccinated with either monovalent or trivalent vaccines were tested in both the CTB-ELISA and the serum neutralisation test (SNT); titres in both tests correlated positively (P less than 0.001). Titres of sera from cattle, sheep, and pigs vaccinated twice with FMDV A10 Holland also correlated positively in both tests. In another experiment, cattle vaccinated with FMDV strain C1 Detmold were intradermolingually challenged 3 weeks after primary vaccination; at the same time two controls were challenged. At 8 days after challenge, serum titres of the controls were distinctly higher in the CTB-ELISA than in the SNT, whereas serum titres of the vaccinated cattle were equally high in both tests. In potency tests for monovalent vaccines against FMDV strains A10 Holland, O1 BFS or C1 Detmold, serum titres correlated strongly in both tests with protection against the homologous FMDV strain. We concluded that the CTB-ELISA is not only sensitive, but easier to perform and more rapid and reproducible than the SNT. The CTB-ELISA may be useful in evaluating the immune response in cattle during FMD vaccine potency tests.     

Relationship between the anti-FMD virus antibody reaction as measured by different assays, and protection in vivo against challenge infection.

The antibody response of cattle after vaccination against foot-and-mouth disease (FMD) virus was monitored using the serum neutralization test (SNT), the sandwich ELISA, liquid-phase ELISA, sandwich competition ELISA, liquid-phase competition ELISA, and the liquid-phase sandwich competition (blocking) ELISA. The competition ELISAs (in particular the "blocking" ELISA) were the most effective at detecting reactivity in these cattle sera. However, 95% of negative sera also competed in the most sensitive ELISA (the "blocking" ELISA) to titres of 1:32 (4% of the sera competed to a titre of 1:128). Comparisons between the different ELISAs, and between these ELISAs and the SNT, demonstrated that the tests were not measuring exactly the same reaction of antibody with FMD virus. With respect to the capacity of animals to resist FMD virus challenge, neither the SNT nor the competition ELISAs were consistently able to identify such animals. The anti-FMD virus antibody titres obtained could be classified into three zones; the "white zone" wherein antibody titres were high and donor animals likely to be protected; the "black zone" wherein antibody titres were low and donor animals likely to be susceptible to infection; the "grey zone" wherein the antibody titres were intermediary and no interpretation could be made with respect to protection. Assays such as ELISA and SNT cannot and do not measure immunological protection; they are a measure of antibody responses and nothing more, and should be interpreted in terms of the "three zone" phenomenon.     

Immunization of cattle against Aujeszky's disease with inactivated adjuvant vaccine

The experiments with sheep and young cattle were carried out to test the immunizing efficacy of inactivated adjuvant vaccine against Aujeszky's disease. The vaccine application at doses of 1 ml and 2 ml to lambs at the age of eight to ten months caused the neutralizing antibody production with a significant rise of titres after revaccination. A survival of infection induced with a dose of 10(5.5) TKID50 of virulent virus was recorded in 62.5% of once vaccinated animals and in 87.5% of twice vaccinated animals. When applying different doses of vaccines (from 1 to 10 ml) to young cattle, the antibody reaction level was directly dependent on the inoculum quantity. The double inoculation of animals with vaccines of 2 ml and 5 ml caused the neutralizing antibody production at titres of 1:35, or 1:46. The animals, immunized with the live or inactivated IBR-vaccine possessing high antibody titres against IBR-virus, reacted upon the vaccination with inactivated Aujeszky's vaccine anamnestically, by early production of antibodies in high titres. Metaphylactic vaccination (2 ml of vaccine) of cattle in herds with an acute course days, however earlier during five days from the revaccination when it was carried out in seven days following the first vaccination.     

Analysis by ELISA and Western blotting of antibody reactivities in cattle infected with Mycobacterium paratuberculosis after absorption of serum with M phlei

Preabsorption of cattle serum with Mycobacterium phlei was of value in eliminating falsely positive reactions in an enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies against M paratuberculosis. Specific antibody titres from 16 animals naturally infected with M paratuberculosis were unaffected by absorption. Analysis by Western blotting indicated that a different set of antigens of M paratuberculosis were recognised by serum from falsely positive reactors compared with that from animals with established infection. After experimental infection the time required for seroconversion in the ELISA in nine calves lay between 10 and 28 months, although one animal had not seroconverted after 30 months when the experiment ended. All animals shed M paratuberculosis in their faeces before seroconversion.     

Duration of protective immunity and antibody responses in cattle immunised against alcelaphine herpesvirus-1-induced malignant catarrhal fever

ABSTRACT: Protection of cattle from alcelaphine herpesvirus-1 (AlHV-1)-induced malignant catarrhal fever (MCF) has been described previously, using an attenuated virus vaccine in an unlicensed adjuvant. The vaccine was hypothesised to induce a protective barrier of virus-neutralising antibody in the oro-nasal region, supported by the observation of high titre neutralising antibodies in nasal secretions of protected animals. Here we describe further analysis of this vaccine strategy, studying the effectiveness of the vaccine formulated with a licensed adjuvant; the duration of immunity induced; and the virus-specific antibody responses in plasma and nasal secretions. The results presented here show that the attenuated AlHV-1 vaccine in a licensed adjuvant protected cattle from fatal intranasal challenge with pathogenic AlHV-1 at three or six months. In addition, animals protected from MCF had significantly higher initial anti-viral antibody titres than animals that succumbed to disease; and these antibody titres remained relatively stable after challenge, while titres in vaccinated animals with MCF increased significantly prior to the onset of clinical disease. These data support the view that a mucosal barrier of neutralising antibody blocks infection of vaccinated animals and suggests that the magnitude of the initial response may correlate with long-term protection. Interestingly, the high titre virus-neutralising antibody responses seen in animals that succumbed to MCF after vaccination were not protective.     

Foot-and-mouth disease in British deer: transmission of virus to cattle, sheep and deer.

After exposure for two hours to cattle with foot-and-mouth disease, each of the five species of deer found in the British countryside became infected. Clinical disease was typical and severe in the roe and muntjac deer, with some animals dying, less severe in the sika deer and usually subclinical in the fallow and red deer. Each species transmitted disease to its own species and to cattle and sheep. The amounts of virus present in the blood, and in oesophageal/pharyngeal samples and excreted as an aerosol during the course of the infection in the deer were similar to those recorded for the sheep and cattle in the same experiment. The fallow and sika deer commonly carried virus in the pharynx beyond 28 days after exposure; some red deer also became carriers. In epidemics of foot-and-mouth disease in the UK, it is likely that deer would have such intimate contact with farm animals as occurred in this study. The natural behavior of free-living deer in the UK suggests that, although the five species are susceptible to foot-and-mouth disease, they are unlikely to be an important factor in the maintenance and transmission of the virus during an epidemic of foot-and-mouth disease in domestic livestock.     

A possible role of capybaras (Hydrochoerus hydrochoeris hydrochoeris) in foot-and-mouth disease (FMD) endemicity

The susceptibility of capybaras exposed to foot-and-mouth disease (FMD) virus by the intramuscular route and the rodents' close coexistence with cattle in FMD endemic ecosystems suggested that the species might play an important role in the virus' survival in the field.In the present study 2 capybaras and 2 cattle were exposed by contact to a capybara inoculated intramuscularly with FMD virus. Both pairs of exposed animals were then used as a contact source with another 2 cattle and 2 capybaras, respectively. All the animals became infected prior to the appearance of clinical lesions in the respective donor animals and developed generalized FMD clinical lesions. Specific neutralizing antibodies and antibodies to virus-infection-associated antigen (VIA) were also developed.Virus was isolated from feces and from throat swabs of 1 of the capybaras up to 17, but not at 23 days post-contact. Virus was isolated from the remaining animals up to 7–14 days post-contact.The results indicate that these rodents might transmit virus over long distances due to their migratory movements, but probably do not act as natural virus reservoirs.     

Endurance of immunity against foot-and-mouth disease in cattle after three consecutive annual vaccinations

Protection against foot-and-mouth disease (FMD) and ability to transmit FMD virus to susceptible contact animals were studied in cattle vaccinated three times in annual field campaigns with the Dutch trivalent vaccine. Eighty vaccinated cattle and 16 susceptible controls were intranasally exposed to an aerosol containing a homologous FMD challenge virus (O1 BFS, A10 Holland or C1 Detmold) or a heterologous virus (A5 Modena or C1 Modena). The day after exposure, vaccinated cattle were stabled individually with an FMD-susceptible contact. All cattle challenged with an homologous virus strain at one year (20 head), at two years (10 head) and at three years (30 head) after the last vaccination were protected against the development of clinical signs of disease; one, zero and five cattle of these groups, respectively, transmitted virus to their contacts. In each group, approximately two out of three exposed cattle had virus-positive oropharyngeal fluid samples and seroconverted. The amount of virus recovered from probang samples increased with the time since the last vaccination. Mean antibody titres of cattle that had not been vaccinated for three consecutive years did not change significantly over the last two-year period. All 10 cattle challenged with the vaccine strain-related C1 Modena virus were protected against clinical disease, whereas three out of 10 challenged with the heterologous A5 Modena strain virus one year after the last vaccination contracted FMD and transmitted the virus. Five others (four in the C1 group and one in the A5 group) spread the virus to their contacts.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prevalence of seroreagents to FMDV in the cattle population in Poland: results of 9-year monitoring studies

The aim of this study was to evaluate the occurrence of antibodies to foot-and-mouth disease virus (FMDV) in sera of cattle in Poland. The examinations were performed using the virus neutralization (VN) test and ELISA methods: liquid-phase blocking ELISA (LPBE) and 3ABC-ELISA. During 1993-2001, about 681,000 samples of sera collected from animals held on the territory of Poland were tested. Of about 600,000 sera taken from animals exported to the European Union, 963 samples (0.16%) were found to be positive to FMDV types A, O and/or C. During 1996-2001 out of 85,000 sera tested as part of the national serological surveillance program for FMD, the FMDV antibodies were recorded in 51 (0.06%) samples. Persistence of FMD antibodies was observed in sera of cattle from the region around Zduńska Wola, which had been vaccinated annually during 1985-1985 with trivalent FMD vaccine. The results of the serological studies of 550 animals from this region indicates the presence of FMDV antibodies in sera of 240 (44%) cattle. A half-life of maternal antibodies in sera of calves born to seropositive dams was estimated; the highest level of FMDV antibodies was detected in sera taken from new-born calves aged 5-10 days. The level of FMDV antibodies in beestings of dams was highest during the first 10 hours after parturition; after 24 hours a significant decrease (3-5 times) was found and in two weeks post parturition FMDV antibodies were undetectable in the milk. It was established that all LPBE/VN positive sera of cattle exported from Poland, from the vaccination zone around Zduńska Wola as well as those tested as part of the national serological surveillance program for FMD, were taken exclusively from vaccinated animals or calves born to vaccinated dams.     

宁夏固原市肉牛口蹄疫和布鲁氏菌病血清抗体检测与分析

[目的] 为了调查宁夏固原市肉牛口蹄疫和布鲁氏菌病的流行情况,[方法]通过采集74份不同月龄肉牛血清样本,采用酶联免疫吸附试验(ELISA)对2种疫病抗体进行检测和分析。[结果],抗体阳性率由高到低分别为A型口蹄疫(48.65%)、O型口蹄疫(43.24%)、布鲁氏菌病(12.16%)。混合抗体阳性率中主要以O型和A型口蹄疫混合抗体阳性率最高(58.54%)。O型口蹄疫在西吉县的阳性检出率最高(88.24%),彭阳县最低(6.67%);A型口蹄疫在西吉县阳性检出率最高(82.35%),彭阳县最低(26.67%);布鲁氏菌病在原州区阳性检出率最高(15.00%),泾源县和彭阳县未检出。从不同年龄来看,3种疫病均在＞12月龄的肉牛中阳性率最高,分别为O型口蹄疫69.23%、A型口蹄疫76.92%、布鲁氏菌病15.38%。[结论] 固原市各个县区肉牛养殖地区均出现2种病原感染的情况,以O型和A型口蹄疫混合感染为主。在肉母牛养殖过程中,应加强对以上病原的检疫并采取相应的防控措施。     

Comparison of the immunizing effectiveness of subunit vaccine and inactivated viral oil vaccine against infectious rhinotracheitis of cattle

Trials were conducted on rabbits and cattle to compare the immunizing effectiveness of the subunit vaccine against infectious bovine rhinotracheitis (IBR), representing antigens separated by the solubilization of the IBR virus-infected cells by means of Triton X-100 with oil adjuvant, with the inactivated oil IBR vaccine. The rabbits inoculated and re-vaccinated with both vaccines in an interval of three weeks produced neutralizing antibodies in medium titres, the values of these antibodies were balanced in both groups. Cattle immunized with the subunit vaccine reacted to the inoculation and re-vaccination by producing serum antibodies of higher titres, as compared with the cattle inoculated with the virus vaccine; secretory antibodies were detected only after re-vaccination and had balanced values in both test groups. After intranasal infection with the virulent virus performed after 14 days from re-vaccination, the calves inoculated with the subunit and virus vaccines were protected against clinical disease whereas the non-inoculated control calves fell ill with symptoms characteristic of IBR. The immunized animals of both experimental groups had a smaller amount of virus p.i. in nasal secretions and for a shorter time than the control non-inoculated calves. The intensity of multiplication and persistence of infectious virus excretion were the same in both experimental groups.     

Prevalence of leptospira species among farmed and domestic animals in Greece

A total of 1527 serum samples from pigs, goats, sheep, cattle and dogs in Greece were examined by the microscopic agglutination test and 11-8 per cent of them had antibodies against one or more Leptospira serovars at titres of 1/100 or more. The predominant serovar affecting farm animal species was Bratislava, and Copenhageni was common among dogs and the second most important serovar when all animals were considered together. Another prevalent serovar was Australis, but antibodies to Pomona were detected only in goats and cattle.     

Comparable sensitivity and specificity in three commercially available ELISAs to differentiate between cattle infected with or vaccinated against foot-and-mouth disease virus

Three commercially available ELISAs for the detection of antibodies to the non-structural proteins of foot-and-mouth disease virus (FMDV) were evaluated, using sera from uninfected, vaccinated, infected, inoculated, first vaccinated and subsequently infected, and first vaccinated and subsequently inoculated cattle. We compared antibody kinetics to non-structural proteins, sensitivity, and specificity. One of the ELISAs had a higher sensitivity and much lower specificity than the other two, therefore we established standardised cutoff values for the compared assays using receiver operated characteristic (ROC) curves. Using the standardised cutoff values, all three ELISAs produced comparable results with respect to sensitivity and specificity. Antibody development to non-structural proteins after infection and after vaccination/infection was not significantly different. Development of antibodies, however, both neutralising and directed to non-structural proteins, was significantly delayed after intranasal inoculation as compared to intradermolingual infection. Based on results of sera obtained after vaccination and experimental infection all three assays can be used for testing sera collected between 4 weeks and 6 months after infection. More information is needed on the prevalence of positive reactors in a situation where emergency vaccination has been used and FMD transmission was still observed.