An immunoblotting procedure for detection of antibodies against bovine leukemia virus in cattle.

A sensitive protein immunoblotting (Western blot) procedure has been developed for detecting anti-BLV antibodies in cattle sera. The antibodies against most of the major viral proteins could be detected. This procedure does not give any non-specific background staining and there is absence of any erroneous results due to utilisation of purified viral preparations. The procedure has been applied for detection of antibodies to BLV in a set of 74 sera samples and it has been compared with other commonly used serological tests like ELISA and agar gel immunodiffusion test.     

A survey of bovine leukemia virus resistant bovine leukocyte antigen (BoLA)-DRB3*009:02 allele-carrying Japanese Black cattle in two prefectures in Japan

The bovine leukocyte antigen (BoLA) DRB3*009:02 allele is strongly associated with a low/undetectable bovine leukemia virus (BLV) proviral load. Understanding the status of cattle possessing DRB3*009:02 allele is key for BLV control by breeding. We performed a survey of DRB3*009:02-carrying cattle in two prefectures in Japan using a TaqMan assay developed previously. The allele was found in 3.8% (confidence interval (CI): 3.3–4.3) of 6020 Japanese Black female cattle. A prefecture-level difference was found: the allele was observed in 8.6% CI: 7.5–9.9) of 2242 cattle of the birth prefecture B in Kyushu/Okinawa region, and this percentage was significantly higher than those of prefecture C in Kyushu/Okinawa region (1.3% (CI: 0.4–3.4) of 319) and prefecture A in Chugoku region (0.9% (CI: 0.6–1.4) of 2741), respectively. Consideration on the difference in possession of DRB3*009:02 allele is needed to establish the more efficient control strategy of BLV infection in Japanese Black cattle.     

Protection of colostral antibodies against bovine leukemia virus infection in calves on a California dairy.

A three-year prospective study involving 244 calves was undertaken on a California dairy to evaluate the protective role of colostral antibodies against bovine leukemia virus (BLV) infection in calves. Calves were followed from birth to the time they left their individual hutch (TLIH), at about 90 days of age. The probability of being infected at TLIH and the daily risk of infection between birth and TLIH were modelled using the logistic and the Cox models, respectively. Calves with no detectable antibodies during the first week of life were up to 2.00 and 2.75 times more likely to be infected at TLIH compared to calves with low and high concentrations of antibodies during the first week of life, respectively (p = 0.01). When the daily risk was modelled, calves without antibodies at the estimated day of infection were up to 3.4 and 11.6 times more likely to become infected than calves with low and high concentrations of antibodies on that day, respectively (p less than 0.001). Results indicated that calfhood infection may be reduced by about 45% through the feeding of colostrum with BLV antibodies. Further reduction in infection may be possible by feeding calves milk powder, milk replacer, and/or milk from noninfected cows. Results also indicated that quantification of the effect of a time-dependent risk factor, such as colostral antibody concentration, might be affected if treated as a fixed factor.     

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.     

Seroprevalence of antibodies against bovine leukemia virus, bovine viral diarrhea virus, Mycobacterium avium subspecies paratuberculosis, and Neospora caninum in dairy cattle in Saskatchewan

Blood was drawn from 1530 dairy cows in 51 herds. For antibodies against bovine leukemia virus, Mycobacterium avium subspecies paratuberculosis, and Neospora caninum, 37.4%, 2.7%, and 5.6% of cows were test positive, respectively, while 29.2% of herds had unvaccinated animals with > or = 1:64 for bovine viral diarrhea virus.     

Seroepizootiological survey of Japanese encephalitis virus and Getah virus in regional horse race tracks from 1991 to 1997 in Japan.

A sero-epizootiological survey was conducted for Japanese encephalitis virus (JEV) and Getah virus (GeV) at 10 to 20 regional horse race tracks from 1991 to 1997 in Japan. It was observed that geometrical mean (GM) antibody titer to JEV and GeV was 10 to 50 times higher than others at several race courses (RCs) almost every year. Of them, several race horses showing high antibody titer, which were suggested to be infected with the virus, were also observed in this survey. These data suggested that the viruses have spread among race horses almost every year in Japan, although, fortunately, no horse showing clinical illness due to these viruses was observed. The calendar years and the names of the race courses in which the spread of JEV was suggested were Sonoda and Nakatsu RCs in 1991, Nakatsu RC in 1992, Arao RC in 1993, Nagoya RC in 1994, Kaminoyama, Urawa, Saga and Arao RCs in 1995 and Ooi and Saga RCs in 1997. Spread of JEV was not observed in 1996. The calendar year and name of the race courses at which the spread of GeV was suggested were at Ooi, Sonoda and Nakatsu RCs in 1991, Arao RC in 1992, Nakatsu RC in 1994 and 1995, Funabashi RC in 1996, Saga RC in 1997. It was suggested that surveillance of JEV and GeV should be continued in the future in at least the southern to middle parts of Japan. It has also been suggested that it is necessary to promote the wider use of vaccines to persons related to horse racing.     

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.     

Syncytium-induction inhibition test with complement for detection of antibodies against bovine leukemia virus.

A modified syncytium-induction inhibition test which is more sensitive than the immunodiffusion test, was developed using rabbit complement. In this test, fetal lamb kidney cells continuously infected with bovine leukemia virus were used as effector cells, and the CC81 cat cells transformed with murine sarcoma virus, were used as indicator cells. The syncytium-induction inhibition effect of anti-bovine leukemia virus serum was enhanced significantly by the addition of rabbit complement. The syncytium-induction inhibition titers had a statistically significant correlation with the immunodiffusion titers and were four to 64 times higher than immunodiffusion titers. In 12 experimentally infected cattle, the syncytium-induction inhibition test detected the antibodies earlier than the immunodiffusion test and continuously detected them when immunodiffusion antibody changed to negative. In the 81 sera from naturally infected herds, 35 (43.2%) were positive by the immunodiffusion test and 55 (67.9%) by the syncytium-induction inhibition test.     

The recent prevalence of bovine leukemia virus (BLV) infection among Japanese cattle

A seroepidemiological survey of bovine leukemia virus (BLV) infection was conducted in Japan in 2007 using an enzyme-linked immunosorbent assay (ELISA) and an agar gel immunodiffusion (AGID) test. A total of 5420 cattle (dairy, 3966; breeding beef, 797; fattening beef, 657) from 209 farms in seven prefectures in Japan were tested. The overall prevalence of BLV infection was 28.6%. The prevalence of BLV infection in dairy cattle (34.7%) was higher than for both fattening beef cattle (7.9%) and breeding beef cattle (16.3%). Age-specific prevalence showed that BLV prevalence increased with age in all types of cattle and was notably different between dairy and beef cattle under 1 year of age. Among 207 farms, 141 herds (68.1%) had one or more positive animals. The proportion of these positive farms was significantly higher among dairy farms (79.1%) than among beef breeding farms (39.5%) and beef fattening farms (51.9%) (P < 0.001). Dairy farms (40.5%) also showed a significantly higher within-herd prevalence than beef breeding (27.4%) and fattening (14.9%) farms (P = 0.001). This study indicated that BLV is more widely spread in dairy cattle than in beef breeding cattle in Japan. Given the prevalence of BLV infection in dairy and beef cattle was 8- and 1.7-fold higher, respectively, than rates previously found in 1980–1982, BLV appears to be spreading particularly among the dairy cattle population during the last two decades. Further investigation is required to determine the risk factors necessary to control BLV infection that take into account the different farming practices that exist between dairy and beef sectors.     

Seroprevalences of antibodies against bovine leukemia virus, bovine viral diarrhea virus, Mycobacterium avium subspecies paratuberculosis, and Neospora caninum in beef and dairy cattle in Manitoba

Of 1204 dairy cows and 1425 beef cows sampled, 60.8% and 10.3% were seropositive for Bovine leukemia virus, 4.5% and 1.7% were seropositive for Mycobacterium avium subspecies paratuberculosis, and 8.3% and 9.1% were seropositive for Neospora caninum, respectively, while 28.1% of dairy herds had unvaccinated animals with titres > or = 1:64 for Bovine viral diarrhea virus.     

A survey of new zealand cattle sera for antibodies to infectious bovine rhinotracheitis virus

Abstract

Extract

Infectious bovine rhinotracheitis (IBR) virus has been associated with respiratory infection (Webster and Manktelow, 1959 Webster, R. C. and Manktelow, B. W. 1959. Some; observations on bovine rhinotracheitis in New Zealand. N.Z. vet. J., 7: 143–148. [Taylor &; Francis Online] , [Google Scholar]) and genital infections (Manktelow and Hansen, 1961 Manketlow, B. W. and Hansen, N. F. 1961. The isolation of a cytopathic agent resembling the virus of infectious bovine rhinotracheitis from an outbreak of pustular vulvovaginitis in cattle. N.Z. vet. J., 9: 136–140.  [Google Scholar]) in New Zealand. The possible role of IBR virus in abortion has been reviewed by Durham (1974 Durham, P. J. K. 1974. Infectious bovine rhinotracheitis virusand its role in bovine abortion. N.Z. vet. J., 22: 175–179. [Taylor &; Francis Online] , [Google Scholar]).     

A survey of antibodies to arthropod-borne viruses in Japanese cattle

Sera collected from the southern parts of Japan were subjected to serological tests for antibodies to 24 arthropod-borne or suspected arthropod-borne viruses. A high incidence (82%) of hemagglutination-inhibiting (HI) antibodies was found with Japanese encephalitis (JE) virus. HI antibodies to other Flaviviruses, Murray Valley encephalitis, Apoi, Kunjin, Stratford and Kokobera, were also found in some of the sera, but seemed to be due to cross reaction with JE virus. High neutralizing (NT) antibody incidences were obtained with Akabane (60%) and Aino (30%) viruses known to be endemic in Japan. NT antibodies were also found for Bunyaviruses, Batai and Wongla; Reoviridae viruses, D'Aguilar, Warrego, and Mitchell River; and Kowanyama and Belmont viruses. Complement fixing antibodies were found for Reoviridae viruses bluetongue type 1 and Ibaraki; Picornavirus Nodamura and Rhabdovirus bovine ephemeral fever. No antibodies were detected with Reoviridae viruses Corriparta and Eubenangee; Bunyavirus Trubanaman; and Alfavirus Chikungunya.     

Rectal palpation and transmission of bovine leukemia virus in dairy cattle.

To determine whether rectal palpation, using common obstetrical sleeves, serves as a mode of transmission of bovine leukemia virus in dairy cattle, field studies were conducted at 2 dairies. At a commercial dairy, significant difference was not observed in rate of seroconversion in heifers and cows in which the same sleeve or new sleeves were used for palpations. At a university dairy, where cattle were used to teach dairy husbandry and veterinary procedures, significantly (P less than 0.02) greater rate of seroconversion was observed in heifers and cows palpated with unwashed common sleeves than that observed in heifers and cows palpated with sleeves washed between use. Although rectal transmission of bovine leukemia virus under field conditions was documented, it was related to frequency of palpation and age of cattle.