Response of cattle persistently infected with bovine virus diarrhoea virus to bovine leukosis virus

Six cattle persistently infected with bovine virus diarrhoea virus (BVDV) and seronegative, and two control, virus negative seropositive cattle were inoculated with lymphocytes infected with bovine leukosis virus (BLV). The two controls produced a normal immune response to BLV, developing antibodies at four and five weeks after inoculation. Two of the six cattle persistently infected with BVDV developed a strong antibody response by six weeks after inoculation with BLV. Four developed a depressed response to BLV, characterised in three by a 'hooking' reaction in the immunodiffusion test which persisted in successive bleedings but was interspersed occasionally by a weak positive reaction. In one of these animals, a series of 'hooking' reactions was followed by a number of negative results. The fourth animal remained serologically negative until 16 weeks after inoculation when a 'hooking' reaction was observed followed by a series of negative results. BLV was isolated from all the cattle persistently infected with BVDV at 42 or 58 weeks after inoculation regardless of whether the serum samples gave negative, 'hooking', weak positive or positive reactions in the immunodiffusion test. BLV was consistently isolated from the nasal secretions of a steer which was BVDV negative but seropositive. The possibility of decreased immune responsiveness to BLV in animals persistently infected with BVDV should be considered when formulating regulations governing the testing of animals for freedom from BLV.     

Serological detection of multiple retroviral infections in cattle: bovine leukemia virus, bovine syncytial virus and bovine visna virus

Individual experimental animals used in our studies on bovine leukemia virus (BLV) are routinely screened for the presence of antibodies to the three bovine lymphotropic retroviruses. We utilized these screening methods to examine frozen sera from eight herds for antibodies to BLV, bovine visna virus (BVV) and bovine syncytial virus (BSV). Serum samples from 235 animals in four dairy and four beef herds were analyzed. Detection methods used included indirect fluorescent antibody tests of virus-infected cell cultures (BLV, BSV, BVV) and agar gel immunodiffusion (BLV). Sera from the BLV-infected animals in the dairy herds showed the highest single (50%, 49/97) and multiple (30%, 29/97) infections compared with 5% (7/138) and less than 1% (1/138), respectively in the beef herds. Single BVV infections were not detected in the dairy herds, but 11% (11/97) of the sera contained antibodies to BVV plus BLV or BSV. Five sera from beef cattle had antibodies only to BVV and four were obtained from one herd. Only one beef serum of the 138 tested demonstrated multiple antibodies (BLV, BVV).     

Detection of bovine virus diarrhea virus in a live bovine herpes virus 1 marker vaccine

In February 1999, 12 Dutch herds were vaccinated with a live bovine herpesvirus 1 vaccine from which bovine virus diarrhea virus (BVDV) could be isolated. All vaccine batches that were on the Dutch market and that had not yet reached the expiry date were tested for BVDV. In total, seven of 82 batches tested were found positive. Batch numbers TX3607, VB3914, VB3915, VB4046, TW3391, and TV3294 were positive for BVDV type 1, and batch number WG4622 was positive for BVDV type 2. This latter batch induced clinical signs of BVDV in an animal experiment with susceptible animals.     

新疆阿克苏地区牛传染性鼻气管炎病毒与牛副流感病毒3型感染的检测

为调查阿克苏地区是否存在牛传染性鼻气管炎病毒(IBRV)与牛副流感病毒3型(BPIV-3)的感染,从阿克苏两个规模化奶牛场采集1月龄以内可疑发病犊牛鼻液样品18份,采用双抗体夹心ELISA方法检测两种病毒的抗原,PCR方法检测牛传染性鼻气管炎病毒gD基因,RT-PCR方法检测牛副流感病毒3型的gM基因。结果表明,ELISA方法检测IBRV和BPIV-3的感染率分别为22.22%和0%;PCR方法检测IBRV的感染率为72.22%;RT-PCR检测BPIV-3的感染率为44.44%;同时患有两种病毒的检出率为22.22%。说明在阿克苏地区存在IBRV与BPIV-3的感染,且存在两种病毒的双重感染。     

Seroprevalence of bovine immunodeficiency virus and bovine leukemia virus in draught animals in Cambodia

Since bovine immunodeficiency virus (BIV), known as bovine lentivirus, has been detected in dairy and beef cattle in various countries around the world, a prevalence study of antibodies to BIV and bovine leukemia virus (BLV) was conducted in draught animals in five provinces in Cambodia, where protozoan parasite infections were suspected in some animals. To clarify the status of draught animals including Haryana, Brahman, mixed-breed, local breed cattle and muscle water buffaloes, a total of 544 cattle and 42 buffaloes were tested, and 26.3 and 16.7%, respectively, were found positive for anti-BIV p26 antibodies determined by Western blotting. There were 5.3% positive for anti-BLV antibodies detected by immunodiffusion test among the cattle, but no reactors among buffaloes and no dual infection for both BIV and BLV was determined in this study. Peripheral blood mononuclear cells from BIV-seropositive cattle were found to have BIV-provirus DNA, as detected by polymerase chain reaction and subsequent Southern blot hybridization. This is the first evidence for the presence of BIV and BLV infections in draught animals in tropical countries such as Cambodia. This wide distribution of BIV suggests its association with problems in animal health as reported worldwide, and that a primary BIV infection can predispose death of affected animals by other aggressive pathogens or stresses.     

Studies on bovine Breda virus

Diarrheic feces from 21 calves were examined by electron microscopy and 16 contained particles morphologically similar to those of Breda virus. The particles were spherical or elongated, 60-270 nm in greatest dimension and had surface spikes 9-13 nm long. Convalescent serum from a human patient with Breda virus-associated diarrhea reacted with one of the bovine viruses by immune electron microscopy, suggesting a serological resemblance between human and bovine Breda-like viruses. Immune electron-microscopy and immunofluorescence demonstrated that isolates of bovine Breda virus from the U.S.A. were related to the French virus. One of the viruses had a density in sucrose solution of 1.16, similar to the value for Berne virus.     

Vertical transmission of bovine leukemia virus and bovine immunodeficiency virus in dairy cattle herds.

Vertical transmission of bovine leukemia virus (BLV) and bovine immunodeficiency virus (BIV) was investigated in five dairy cattle herds in Hokkaido, where 36.1 and 17.0% of cattle were BLV and BIV seropositive, respectively, and 9.9% of dams were co-infected with both BIV and BLV. Twenty six cases of offspring born from dams infected with only BLV (17 cases) or with both BIV and BLV (9 cases) were examined for the presence of BLV and BIV before and after colostrum feeding by polymerase chain reaction (PCR) and syncytium assay. After birth, all calves were separated immediately from their dams. The offspring born from BLV-positive dams were BLV-negative before colostrum feeding, suggesting that no transplacental transmission had occurred. Thereafter, these offspring were fed colostrum or milk from their dams, but still remained BLV-negative. The other offspring born from BLV-positive dams were fed with BLV-negative colostrum, or with pasteurized BLV-positive colostrum. All these calves remained negative for BLV infection, suggesting that in utero transmission of BLV is negligible. In the case of offspring born from dams co-infected with BLV and BIV, calves were BIV-positive before colostrum feeding at 1 day after the birth, indicating in utero transmission of BIV. After colostrum feeding from their dams, newborn calves became BLV-positive. In addition, one calf was BLV-positive even before colostrum feeding. These results suggest that BIV can be transmitted to offspring in utero, and that BLV can be transmitted through colostrum or milk if dams are infected with both BIV and BLV.     

Prevalence of antibodies to bovine respiratory syncytial virus, bovine viral diarrhea virus, bovine herpesvirus-1, and bovine parainfluenza-3 virus in sheep and goats in Quebec

Serum samples were collected from 1,075 clinically normal sheep and goats from 77 flocks in 7 agricultural regions of Quebec from June to August 1982. Sheep and goats were tested for antibodies to bovine respiratory syncytial virus, bovine viral diarrhea virus, and bovine herpes-virus-1 by the indirect fluorescent antibody technique and for parainfluenza-3 virus by the hemagglutination inhibition test. The prevalence of antibodies in animals to respiratory syncytial virus was 31%; to bovine viral diarrhea virus, 22.2%; to bovine herpesvirus-1, 10.8%; and to parainfluenza-3 virus, 23.2%. Antibodies prevailed in similar proportions in young (less than 1 year) and adult (greater than 1 year) animals.     

Seroprevalence of bovine immunodeficiency-like virus and bovine leukemia virus in a dairy cattle herd.

To determine the prevalence of single vs. dual infection with bovine immunodeficiency virus (BIV) and bovine leukemia virus (BLV), sera (n = 95) from a dairy cattle herd were analyzed for anti-BIV and anti-BLV antibodies by an enzyme linked immunosorbent assay. Twenty-one percent (20/95) of samples were BIV-seropositive, while 52% (49/95) of the same samples were BLV-seropositive. A significantly greater percentage of BIV-seronegative samples were BLV-seropositive, 57% (43/75), than were BIV-seropositive samples, 30% (6/20). There was no significant correlation between data ranked from least to greatest amount of anti-viral antibody. Five cattle had persistent lymphocytosis (PL); all five were BLV-seropositive and two were BIV-positive. The mean anti-BLV titer was significantly greater in PL cattle, as compared at non-PL cattle, whereas there was no significant difference between the mean anti-BIV titer in PL cattle, as compared with non-PL cattle. These results provide additional information on the seroprevalence of naturally occurring BIV infection, and indicate that BIV can exist independent of other common infectious agents, such as BLV. Further, the results suggest that infection with BIV is not associated with an increased rate of infection with other infectious agents such as BLV.     

Survival of infectious bovine rhinotracheitis virus in stored bovine semen

No loss in the titre of infectious bovine rhinotracheitis virus was found during storage in semen at –196°C for 1 year.     

Persistent bovine virus diarrhoea virus infection in a bull

Investigation of a sight defect in a pedigree bull, born as a result of artificial insemination and ovum transplantation, led to the finding that the animal was persistently infected with bovine virus diarrhoea virus. Virus was cultured from blood and from nasal and ocular swabs and was present in semen in high titre. At necropsy, virus was cultured from a wide range of tissues. The pathological findings are described and discussed as are the potential hazards of such infections.     

Outbreak of bovine virus diarrhea on Dutch dairy farms induced by a bovine herpesvirus 1 marker vaccine contaminated with bovine virus diarrhea virus type 2

On 23 February 1999, the Dutch Animal Health Service advised all Dutch veterinary practices to postpone vaccination against bovine herpesvirus 1 (BHV1) immediately. The day before severe disease problems were diagnosed on four dairy farms after vaccination with the same batch of BHV1 marker vaccine. Using monoclonal antibodies, bovine virus diarrhoea virus (BVDV) type 2 was found in the vaccine batch. This paper describes an outbreak of BVDV type 2 infection caused by the use of a batch of modified live BHV1 marker vaccine contaminated with BDVD. Sources of information used were reports of farm visits, minutes of meetings, laboratory results, and oral communications from the people involved. The first symptoms of disease were observed on average six days after vaccination. Morbidity was high on 11 of the 12 farms. On five farms more than 70% of the animals became ill, while on one farm no symptoms could be detected. During the first week after vaccination, feed intake and milk production decreased. During the second week, some animals became clinically diseased having nasal discharge, fever, and diarrhoea. At the end of the second week and at the start of the third week, the number of diseased animals increased rapidly, the symptoms became more severe, and some animals died. Mortality varied among herds. Necropsy most often revealed erosions and ulcers of the mucosa of the digestive tract. In addition, degeneration of the liver, hyperaemia of the abomasum, and swollen mesenterial lymph nodes and swollen spleen were found. On 11 of the 12 farms all animals were culled between 32 and 68 days after vaccination after an agreement was reached with the manufacturer of the vaccine. This was the third outbreak of BVD in cattle after administration of a contaminated vaccine in the Netherlands. The possibilities to prevent contamination of a vaccine as a consequence of infection of fetal calf serum with BVDV are discussed. Improvement of controls to prevent contamination before and during vaccine production, and improvement of the monitoring of side-effects is necessary.