山羊关节炎-脑炎研究进展

山羊关节炎-脑炎(Caprine arthritis encephalitis，CAE)是由反转录病毒科慢病毒属山羊关节炎脑炎病毒(CAEV)引起的山羊的慢性传染病。临床症状以山羊羔脑脊髓炎和成年山羊多发性关节炎、硬结性乳房炎以及间质性肺炎为特征。在未认识该病之前，对其说法不一。1964年Stunzi在瑞士称其为山羊慢性淋巴细胞性多发性关节炎；1969年Starrou在德国发现，称其为山羊肉芽肿性脑脊髓炎；1974年Cark等在美国报道为山羊病毒性白质脑脊髓炎。     

山羊关节炎-脑炎的研究现状

山羊关节炎-脑炎(Caprine Arthritis-Encephalitis,CAE)是由山羊关节炎-脑炎病毒(Caprine Arthritis-Enceephalitis Virus,CAEV)引起的一组临床病症.临床出现以慢性持续性病症为特征的羔羊的急性脑脊髓炎,成年羊的关节炎、乳腺炎、慢性进行性肺炎和脑炎等[1].     

An epidemic of caprine arthritis encephalitis in Japan: isolation of the virus

A disease characterized by arthritis of carpal joints and occasionally by pneumonia was seen among goats on a farm in Nagano prefecture of Japan in the summer of 2002. Serological investigation was done on 30 goats, that is one group on the farm by agar gel immunodiffusion tests using maedi-visna virus as the antigen, and 19 goats were positive. The caprine arthritis encephalitis virus genome was detected in peripheral blood leukocytes from several antibody-positive goats. Two goats among them were necropsied and used for pathological tests and virus isolation. The isolated virus was serially propagated in fetal lamb lung cell cultures. Goats inoculated with the culture fluid became antibody positive. These results suggested that a CAEV-infected goat had been introduced accidentally to the farm and that subclinical infection occurred among the flock.     

The effect of caprine arthritis encephalitis virus infection on production in goats

Three consecutive years of monitoring 248 goats in the same flock, found that the first lactation milk yield was significantly higher in seronegative (578 L) than in seropositive (447 L) animals but this difference disappeared in the subsequent second to fourth lactations. No significant differences were found in the proportions of seronegative and seropositive does in the flock, the percentage of animals culled, the number of offspring, or in the number of cases of udder bacterial infection, irrespective of age.Removal of kids from their dams before suckling and the feeding of pasteurised colostrum resulted in reduced numbers of seropositive animals. Nevertheless, by approximately 24 months of age, 76.9% of these initially seronegative animals were seropositive, a factor that significantly contributed to flock seropositivity. This finding could be attributed to lateral virus transmission from seropositive to seronegative kids because of lack of segregation within the flock.     

Presence of virus particles in neural cells of goats with caprine arthritis encephalitis

The possible neurotropism of ungulate lentivirus was examined in clinical cases. Brain and ganglion tissue samples were examined from six female goats with caprine arthritis encephalitis and from six healthy controls. Ultrastructural examination revealed typical cytoplasmic A type retrovirus particles in the neural tissue of the diseased does. None were seen in the respective controls. Furthermore, no budding or extracellular retrovirus particles were seen in any of the neural tissue samples examined.     

Occurrence of caprine herpesvirus (BHV-6) infection in goat population of the GDR

To clarify the occurrence of the caprine herpesvirus (BHV-6) infection in the goat population in the GDR, 175 sera, collected from the agricultural research station of Karl-Marx-Universit?t at Probstheida were tested for the presence of neutralizing antibodies against BHV-6. BHV-6 antibodies were present in 12% of the sera examined. The titer was low. Cross-neutralization of BHV-6 could not be determined with any other bovine herpesvirus. The goat sera tested were free of neutralizing antibodies against BHV-1 and BHV-3. The indirect immunofluorescence antibody test revealed cross-reactivity only between BHV-6 and BHV-1.     

Small ruminant lentiviruses: immunopathogenesis of visna-maedi and caprine arthritis and encephalitis virus

The small ruminant lentiviruses include the prototype for the genus, visna-maedi virus (VMV) as well as caprine arthritis encephalitis virus (CAEV). Infection of sheep or goats with these viruses causes slow, progressive, inflammatory pathology in many tissues, but the most common clinical signs result from pathology in the lung, mammary gland, central nervous system and joints. This review examines replication, immunity to and pathogenesis of these viruses and highlights major differences from and similarities to some of the other lentiviruses.     

Serological evidence of lack of contact with caprine herpesvirus type 1 and bluetongue virus in goat population in Poland

Investigation into herd-level seroprevalence of caprine herpesvirus type 1 (CpHV-1) and bluetongue virus (BTV) was conducted in 2007 in Poland. It involved the entire population of goats covered by a milk recording program in 2007, which included 49 goat herds. The number of goats examined in each herd was determined statistically in order to detect the presence of at least one seropositive animal in a herd with a 95% probability and simple random method of sampling was applied. No antibodies to CpHV-1 or BTV were detected. Further calculations were carried out to determine the herd-level true seroprevalence, taking into account sensitivity and specificity of the test as well as several other factors. It can be concluded that till the middle of 2007 population of Polish goats covered by the milk recording program remained negative with respect to CpHV-1 and BTV.     

Seroprevalence and risk factors of caprine toxoplasmosis in Minas Gerais, Brazil

The objective of this work was to carry out a study on caprine toxoplasmosis in the state of Minas Gerais, Brazil. To determine the prevalence of toxoplasmosis in goats in Minas Gerais, 767 sera from goats were tested by ELISA (enzyme-linked immunosorbent assay) and IFAT (indirect fluorescence antibody test). The prevalence of antibodies to Toxoplasma gondii was 43.0% and 46.0% by ELISA and IFAT, respectively. It was observed that 26.8% of the goats show low-avidity IgG to T. gondii. These results suggest the presence of animals in recent phase of toxoplasmosis in Minas Gerais. The risk factors for toxoplasmosis in goats were: age over 36 months (OR = 1.21; IC 95% 1.02–1.44), use of pen (OR = 1.83; IC 95%1.01–3.31) and pure breed animals (OR = 2.49; IC 95% 1.11–5.59).     

Seroprevalence of Border Disease in Danish sheep and goat herds

A study was conducted in 1994-96 with the aim of assessing the serological prevalence of Border Disease (BD) among sheep and goats in Denmark and to investigate possible relations to herd factors. From each of 1000 herds, 2 blood samples were obtained from animals older than 1 year. The examination for antibodies was performed using a blocking ELISA detecting antibodies to pestivirus. Data from 815 herds were analysed statistically by the maximum likelihood method in a multinomial model. The estimated herd prevalence was 0.083 and the estimated individual prevalence within the positive herds was 0.50. There was no difference between the prevalence in sheep and goat herds. Records for well over half of the herds could be combined with data from the Danish Central Husbandry Register. No association between occurrence of BD and herd size was found. Cattle were registered as contemporarily present on 135 out of 521 herds which was shown to be strongly associated to BD. The estimated herd prevalences of BD among farms with and without contemporary cattle were 0.24 and 0.042, respectively.     

Seroprevalence of caprine arthritis-encephalitis virus in goats in the Cariri region, Paraiba state, Brazil

The seroprevalence of caprine arthritis–encephalitis virus (CAEV) in the Cariri Region of Paraíba State, Brazil, was determined in 60 goat herds using the agar gel immunodiffusion test. The overall seroprevalence was 8.2%, with seropositivity in 21/60 (35%) herds and 13/15 (86.6%) municipalities. Bucks had a significantly higher frequency of infection (28.3%) than does (5.9%), and bucks that originated in other states had a significantly higher frequency of infection (76.5%) than those from Paraíba State (9.3%).     

Seroprevalence of Leptospira Hardjo in the Irish suckler cattle population

Background

Prior to the present study, the seroprevalence of leptospirosis in Irish suckler herds was unknown. In this study, we describe the herd and animal-level prevalence of Leptospira Hardjo infection in the Irish suckler cattle population. For the purposes of the study, the 26 counties of the Republic of Ireland were divided into 6 regions from which a representative number of herds were selected. A herd was considered eligible for sampling if it was not vaccinating against leptospirosis and if it contained ≥ 9 breeding animals of beef breed ≥ 12 months of age. In total, 288 randomly selected herds were eligible for inclusion in the seroprevalence dataset analysis. Serological testing was carried out using a commercially available monoclonal antibody-capture ELISA, (sensitivity 100%; specificity 86.67%).

Results

Herds were categorised as either “Free from Infection” or “Infected” using the epidemiological software tool, FreeCalc 2.0. Using this classification, 237 herds were “Infected” (82.29%). The South West and South East regions had the highest herd prevalence. The regional effect on herd prevalence was largely mirrored by breeding herd size. A true animal-level prevalence of 41.75% was calculated using the epidemiological software tool, TruePrev. There was a statistically significant regional trend, with true prevalence being highest in the South East (P < 0.05). The median Breeding Herd Size (BHS), when categorised into quartiles, had a statistically significant influence on individual animal true seroprevalence (P < 0.001); true seroprevalence increased with increasing BHS.

Conclusions

Leptospirosis is a widespread endemic disease in the Republic of Ireland. It is possible that economic losses due to leptospirosis in unvaccinated Irish suckler herds may be underestimated.     

Seroprevalence of goat toxoplasmosis on Grand Canary Island (Spain)

Sera drawn from 1052 Canary goats on the island of Grand Canary were tested to determine the prevalence of antibodies to (IgG) Toxoplasma gondii using an indirect ELISA test. The total prevalence was 63.31%. Significant differences were found between the island's four climatic zones. The highest seroprevalence was in animals from low altitude zones with very little rainfall, high temperatures and a predominance of trade winds.     

Leptospiral antibodies in the breeding goat population of Poland

In 2007, a survey was conducted on the prevalence of antibodies to 19 Leptospira serovars in goats in Poland . Sera were collected from adult females of all 49 breeding goat herds in Poland by applying simple random sampling. In total, 736 sera were tested by the microscopic agglutination test. A herd was considered seropositive if at least one goat with a titre of 100 or more was detected. Herd-level seroprevalence of Leptospira was 89.8 per cent and individual-level seroprevalence varied from less than 1.0 to 85.0 per cent among the herds. Antibodies to Leptospira serovars Zanoni, Bratislava, Autumnalis, Australis and Javanica were most frequently detected. Although 40.3 per cent of seropositive goats had high antibody titres (≥ 400), suggesting recent infection, no relationship with abortions or other clinical manifestation of leptospirosis in goats was detected.     

Seroprevalence of canine herpesvirus-1 in Turkish dog population

Canine herpesvirus-1 (CHV-1) is the agent of reproductive and respiratory disorders in adult dogs, and the infection generally results in haemorrhagic disease conditions and neonatal death. In this study, virus neutralisation test that used complement (VNT) as well as in-house ELISA were utilised to investigate the CHV-1 seroprevalence in the Turkish dog population. Among the 560 serum samples, 39.3% of the samples tested by ELISA were CHV-1 positive while 29.4% of the samples tested by VNT were CHV-1 positive. Compared to the individual dogs (39.0%), there was a higher CHV-1 seroprevalence (62.1%) found in the colony dogs (62.1%) (p = 0.0002). However, there was an insignificant difference between male and female dogs. Although the highest antibody prevalence (56.7%) was found in Golden Retrievers, there were no significant variations detected among the dog breeds used in this study. Neutralizing antibody titres were very low (?1:16) in a high portion of the tested animals, confirming the rapid decrease of CHV-1 antibodies after the course of infection. The results of this study show that CHV-1 seroprevalence is moderately high in the Turkish dog population.