Serological survey concerning the IBR, CHV2, BVD, PI3, BRS and rinderpest viruses in small ruminants in Zaire

More than 400 small ruminant sera from Za?re were screened for antibodies to IBR, CHV2, BVD, bovine and ovine PI3, BRS and rinderpest viruses. Sera from local animals were negative for BVD, PI3 and rinderpest viruses: 8% of sera were positive for IBR virus, all with higher titers to CHV2; 31% of sera were positive to BRS virus.     

A Controlled Field Study Using Live Virus Vaccines and an Antiserum in a Preconditioning Program

Thirty-five vaccinates and 29 control beef calves from five farms were studied. Vaccinates in group 1 received a modified live virus vaccine against infectious bovine rhinotracheitis (IBR) and bovine virus diarrhea (BVD) 30 days after shipment; vaccinates in groups 2, 3 and 4 received live virus vaccines agains IBR and bovine parainfluenza 3 (PI3) seven to 17 days before shipment. Half of group 5 were given bovine origin antiserum containing antibodies against IBR, BVD and PI3. Three weeks later, the animals that had received serum were given a live modified vaccine containing IBR, BVD and PI3. In group 1, WBC counts were lower in the vaccinates than in the controls for two weeks after vaccination. WBC counts in groups 3 and 4 were higher in vaccinates than in controls after addition to the feedlot. Seroconversions to BVD virus occured in all groups. Clinical disease apparently due to BVD affected one vaccinated calf in group 2 and eight calves in group 5. Combined weight gains were significantly higher in three groups of calves vaccinated before shipment compared to unvaccinated control animals after addition to the feedlot. Vaccination with IBR and PI3 live virus vaccines should be given at least 17 days before shipment to feedlots containing infected cattle. Antiserum containing antibodies against the three viruses showed no apparent advantage in preventing clinical respiratory disease over control calves not receiving the serum.     

Viral aetiologies for bovine respiratory disease

Extract

Bovine respiratory disease (BRD) is a major health problem of cattle all over the world. Financial losses arise from the loss in production, cost of treatment and mortality. Incidence varies with seasons, the highest occurring in autumn and winter. Virus infections such as infectious bovine rhinotracheitis (IBR), parainfluenza 3 (P13) and bovine respiratory syncytial (BRS) viruses have all been incriminated as causes for BRD. It has been suggested that bovine viral diarrhoea (BVD) virus may also contribute to BRD because of its immunosuppressive effects, thus increasing the susceptibility of the host to other respiratory pathogens.     

A study of some infectious causes of reproductive disorders in cattle owned by resource-poor farmers in Gauteng Province, South Africa

Two hundred and thirty-nine cattle from Gauteng Province in South Africa were tested for various pathogens causing reproductive diseases includingbovine viral diarrhoea/mucosal disease (BVD/MD) virus, infectious bovine rhinotracheitis/infectious pustular vulvovaginitis (IBR/IPV) virus, Neospora caninum and Brucella abortus usingvarious tests. For BVD/MD virus, 49.37% tested positive, 74.47% for IBR/IPV virus, 8.96% for Neospora caninum and 3.8% for Brucella abortus. The result for Brucella abortus is higher than the national average, possibly due to the small sample size. A high seroprevalence of antibodies to both BVD/MD virus and IBR/IPV virus was evident. These 2 viruses should be considered, in addition to Brucella abortus, when trying to establish causes of abortion in cattle. The clinical significance of Neospora caninum as a cause of abortion in Gauteng needs further investigation. One hundred and forty-three bulls were tested for Campylobacter fetus and Trichomonas fetus, and a low prevalence of 1.4% and 2.1% respectively was found in this study. The clinical implications of these findings are discussed.     

The role of Mycoplasma bovis in bovine respiratory disease outbreaks in veal calf feedlots

To assess the prevalence and relative importance of Mycoplasma bovis among the pathological agents implicated in bovine respiratory disease (BRD), we surveyed 135 veal calves from nine feedlots in eastern France during naturally occurring outbreaks of respiratory disease. Occurrence of respiratory pathogens, M. bovis, bovine viral diarrhoea (BVD) virus, bovine respiratory syncytial (BRS) virus and parainfluenza-3 (PI3) virus was investigated by seroconversion and isolation of bacteria and viruses from broncho-alveolar fluids. M. bovis and pathogenic respiratory bacteria were isolated in eight of the nine feedlots, and from 106 and 32, respectively, of the 135 tested animals. Seroconversion to PI3 virus occurred in four lots. BVD and BRS viruses were detected in eight and one lot, respectively. M. bovis was the most frequently isolated aetiologic agent in these BRD outbreaks, spreading early and widely throughout the affected units (60-100% rate of isolation and seroconversion). These results stress the importance of M. bovis in the BRD complex.     

Frequency of persistent bovine viral diarrhea virus infection in selected cattle herds

Sera and blood buffy coat samples were obtained from 3,157 cattle in 66 selected herds. Antibodies to bovine viral diarrhea (BVD) virus were detected in 89% of the serum samples by immunoprecipitation or virus-neutralization tests. Cytopathic or noncytopathic BVD viruses were isolated from blood buffy coat samples from 60 cattle in 6 herds. A second blood buffy coat sample was obtained from 54 of the 60 cattle 2 months after the initial sampling, and BVD virus was isolated again from each cow. The 54 cattle were considered persistently infected with BVD virus. The frequency of persistent infection was 1.7%.     

Enzyme linked immunosorbent assay used to monitor serum antibodies to bovine respiratory disease viruses

An enzyme linked immunosorbent assay (ELISA) was applied to the detection of serum antibodies against infectious bovine rhinotracheitis (IBR), parainfluenza-3 (PI3), adenovirus type 3 (adeno 3) and bovine respiratory syncytial (BRS) viruses. Paired serum samples from calves vaccinated with live attenuated virus vaccines were tested. The ELISA compared favorably with the virus neutralization test for detecting serologic responses to IBR, BRS, and adeno 3 viruses or with the hemagglutination inhibition test for PI3 virus. The simplicity, sensitivity and rapidity of the ELISA test makes it a useful tool for immunological studies with respiratory viruses.     

Prevalence of serum antibodies to bovine herpesvirus-1 and bovine viral diarrhea virus in beef cattle in Uruguay

Our objective was to determine the prevalence of serum antibodies to bovine herpesvirus-1 (BHV-1) and bovine viral diarrhea (BVD) virus in beef cattle in Uruguay. A random sample of 230 herds selected with probability proportional to population size based on the number of cattle was chosen from a list frame of all registered livestock farms as of June 1999. Sera from up to 10 heifers, cows and bulls (up to 30 sera total per herd) were collected on selected farms between March 2000 and March 2001 and evaluated by means of enzyme-linked immunosorbent assays (ELISAs). Overall, 6358 serum samples were evaluated. We also collected data on previous diagnosis of BHV-1 or BVD infections and on the use of vaccines against these agents.

The estimated prevalence of exposure to BHV-1 and BVD at the herd level for the Uruguayan beef population was 99% and 100%, respectively. Approximately 37% of beef cattle in Uruguay have been exposed to BHV-1 and 69% to BVD virus. Only 3% of beef herds in Uruguay regularly (typically, annually) use vaccines against either of these agents.     

Demonstration and quantitation of immunoglobulins in bovine serum, follicular fluid, and uterine and vaginal secretions with reference to bovine viral diarrhea and infectious bovine rhinotracheitis.

Immunoglobulin concentrations (IgG, IgM, and IgA) in bovine serum, follicular fluid, and uterine and vaginal secretions were determined. The specificities of IgG, IgM, and IgA for virus-neutralizing antibody against bovine viral diarrhea (BVD) and infectious bovine rhinotracheitis (IBR) viruses were also examined. High concentrations of IgG were present in both serum and follicular fluid. The IgG, IgM, and IgA concentrations were low in uterine and vaginal secretions. There was more IgG in the uterus during estrus than at any other time. Virus-neutralizing antibodies against BVD and IBR in serum of cows were mainly the IgG class. There was positive correlation between serum and follicular fluid virus-neutralizing antibody titers fro BVD and IBR. These antibodies may provide some protection for recently ovulated ova.     

Investigation of causative agents of bovine respiratory tract disease in a beef cow-calf herd with an early weaning program.

Serum samples were collected from early weaned fall calves shortly after the onset of respiratory tract disease. Antibody titers to infectious bovine rhinotracheitis (IBR) virus, parainfluenza type 3 (PI-3) virus, bovine viral diarrhea (BVD) virus, bovine adenovirus type 3 (BAV-3), and bovine respiratory syncytial virus (BRSV) were determined on paired (acute and convalescent) serums. Seroconversion rate (a fourfold or greater rise in antibody titer) for IBR virus was 4.3%, PI-3 virus--16.3%, BVD virus--9.6%, and BAV-3--2.2%. Seroconversion for BRSV was 45.4%. An increased rate of seroconversion for IBR, PI-3, and BVD viruses and BAV-3 was observed in the presence of BRSV seroconversion. These results suggest that BRSV may facilitate infection by other viruses. Results of virus isolation procedures from these calves were negative.     

Serologic examination of aborted ovine and bovine fetal fluids for the diagnosis of border disease, bluetongue, bovine viral diarrhea, and leptospiral infections

Fetal serum from most of 994 bovine and 553 ovine aborted fetuses was tested serologically for antibodies to border disease (BD), bovine viral diarrhea (BVD), and bluetongue (BT) viruses, and to Leptospira sp., and the results were compared with the results of isolation procedures, fluorescent antibody tests (FAT), and histologic examinations of the same fetuses. Antibodies to BT virus were not found in any of the 994 bovine and 553 ovine fetuses. Antibody titers to BVD virus were present in 39 of 966 bovine fetuses tested, and BVD virus was detected in 4 of the 39. Four of 74 fetuses in which the BVD virus was detected by FAT or isolation had titers to BVD virus. Microagglutination (MAT) titers to 1 or more of 5 serovars of leptospires were present in 52 of 773 bovine fetal sera tested. Leptospires were not detected by FAT in any bovine fetuses that had leptospiral antibody titers. Leptospires were detected by FAT in 15 aborted calves, and none of these had MAT titers. Antibody titers to BD virus were present in 80 of 486 fetal lamb sera tested, and the virus was detected by FAT or isolation in 3 of the 80 fetuses. Border disease virus was detected in 14 of 486 fetal lambs tested. Twelve of the 14 were tested serologically and 3 had titers to BD virus. Leptospiral antibody titers were present in 27 of 326 ovine fetal sera tested. Leptospires were not detected in any of the 326 ovine fetuses tested by FAT.     

Maternal immunity to infectious bovine rhinotracheitis and bovine viral diarrhea viruses: duration and effect on vaccination in young calves.

The immune response to modified live-virus bovine viral diarrhea (BVD) vaccine and infectious bovine rhinotracheitis (IBR) vaccine was examined in calves that had received passive maternal antibodies to these viruses. Blood serum samples from vaccinated and control (nonvaccinated) calves were examined for more than 1 year to determine the rate of decline of passive anti-BVD and anti-IBR antibodies and the effect that vaccination had on these antibody titers. The control calves lost their antibodies to BVD and IBR viruses at the rate of one half their remaining antibody titer every 21 days. Calves serologically responded to BVD vaccine at a time when maternal antibody titers remained between 1:96 and 1:20. However, animals did not seroconvert to the IBR vaccine until maternal antibodies had decreased and become undetectable. Evidence is presented to show that although passive immunity will inhibit IBR vaccination, priming for a secondary response will occur so that on subsequent vaccination, at a time when maternal antibodies have disappeared, the animals will respond anamnestically to IBR vaccination.     

In vitro interferon production by bovine tissues: induction with infectious bovine rhinotracheitis virus.

The interferon-inducing ability of infectious bovine rhinotracheitis (IBR) virus was determined in tissue cultures of bovine origin inoculated with untreated and ultraviolet (UV) irradiated IBR viruses. Interferon was assayed by the plaque-reduction method in bovine fetal kidney (BFK) cell cultures, using vesicular stomatitis virus as challenge virus. Highest interferon concentrations were produced by cultures of bovine fetal (BF) spleen cells and aveolar macrophage cultures derived from adult cattle. Moderate interferon concentrations were produced by peripheral blood leukocyte (PBL) suspension cultures from adult cattle with serum-neutralizing antibodies against IBR virus. Cultures of PBL from 1 cow without detectable serum-neutralizing antibodies against IBR virus did not produce detectable interferon in response to IBR virus. Cultures of PBL from cattle with or without detectable serum-neutralizing antibodies against IBR virus produced interferon when stimulated with phytohemagglutinin (PHA). Low levles of viral inhibitors were detected infrequently in monolayer cultures of BFK and BF nasal mucosa inoculated with UV-irradiated IBR virus and in BF tracheal organ cultures inoculated with untreated IBR virus. Interferon was not detected in fluids collected from IBR virus-exposed monolayer cultures of primary and secondary BF lung, secondary BF tracheal mucosa, secondary BF liver, secondary BF adrenal, and PBL in the 4th and 7th passages. The antiviral inhibitors from BF spleen, bovine alveolar macrophage, and PBL cultures induced with IBR virus, as well as inhibitors from PBL cultures induced with PHA, had the usual properties of interferon.     

Active and Passive Immunity to Bovine Viral Respiratory Diseases in Beef Calves After Shipment

Fifteen steers were vaccinated after shipment with a modified live virus vaccine containing infectious bovine rhinotracheitis (IBR), bovine virus diarrhea (BVD), and bovine myxovirus parainfluenza-3 (PI3), and 16 unvaccinated steers were kept as controls. Geometric mean titers one month after vaccination were highest to BVD, followed by PI3 and IBR. Weight gains were higher during 30 days after vaccination in the controls. One case of acute respiratory disease developed in one vaccinated calf. Revaccination 79 days after the first dose increased antibody to PI3 and BVD virus but not IBR. In a second trial, no clinical respiratory disease developed after shipment of 13 heifers that received an antibacterial-antiviral antiserum or in the 12 controls. Weight gains 30 days after shipment were identical in both groups.     

Bovine viral diarrhoea virus infection in cattle,sheep and goats in northern Tanzania

Virological and serological investigations were carried out in cattle, sheep and goats raised in the northern part of Tanzania in order to explore the possibility of bovine viral diarrhoea (BVD) virus cycling within these animal species. Two noncytopathogenic BVD virus isolates (A4/5/Tan86 and A4/10/Tan86) were obtained from sera sampled from inapparently infected indigenous (zebu) cattle originating from Kiteto district in Arusha region. No BVD virus was isolated from any of the sheep or goat sera. Seroepidemiological investigations revealed widespread prevalence of neutralising antibodies to BVD virus not only in cattle but also in sheep and goats. The seropositive rates are discussed in relation to previous observations in Tanzania and other parts of the world and to the livestock husbandry practices in northern Tanzania.     

A preliminary serological survey of viral antibodies in Peruvian sheep

This study reports the sero-prevalence of viral infections in sheep in Peru. Serum samples were collected from 34 mature healthy rams located in 3 different geographic regions of the country (north, central and south). The sera were tested for antibodies to the following viruses: respiratory syncytial virus (RSV); parainfluenza 3 (PI-3) virus; bovine viral diarrhea/border disease (BVD/BD) virus; bovine herpesvirus 1 (BHV-1); bluetongue (BT) virus; ovine progressive pneumoniae (OPP) virus; bovine leukosis virus (BLV). The serological studies showed that 47% were positive for RSV; 82% for PI-3; 3% for BVD/BD virus; 49% for BT virus; 13% for OPP virus. Antibodies were not detected to bovine herpesvirus 1 or to bovine leukosis virus.     

A bovine respiratory virus vaccination trial

A respiratory virus vaccination trial was carried out in a commercial calf-rearing unit with a history of virus pneumonia. The effects of vaccination on the incidence of virus respiratory disease and growth rate were assessed. Forty-four bought-in calves were allocated to groups and treated as follows: A, unvaccinated controls; B, intranasal temperature-sensitive infectious bovine rhinotracheitis (IBR) vaccine at three and 10 weeks; C, intranasal temperature-sensitive combined IBR and parainfluenza-3 (PI3) vaccine at three and 10 weeks; D, intranasal temperature-sensitive combined IBR and PI3 vaccine at three and 10 weeks plus live attenuated bovine respiratory syncytial (BRS) virus vaccine intramuscularly at seven, 10 and 16 weeks. Two outbreaks of virus pneumonia occurred, one at three to four months of age associated with BRS virus and the other at four to five months of age with PI3 virus. During these outbreaks the incidence of pneumonia was lower and the number of days of elevated temperature and the number of treatments were significantly less in groups vaccinated against the associated virus. Despite these findings there were no significant differences between the growth rates of the groups either during the outbreaks of virus pneumonia or during the 10 month period to slaughter.     

Specificity of neutralizing and precipitating antibodies induced in healthy calves by monovalent modified-live bovine viral diarrhea virus vaccines

Serum was obtained at weekly intervals after vaccination of 6 healthy calves with either of 2 commercially available monovalent modified-live bovine viral diarrhea (BVD) virus vaccines. Detectable neutralizing antibodies to each of 10 cytopathic and 10 noncytopathic isolates of BVD virus were produced by 1 or more of the calves by 14 days after vaccination, but no calf produced detectable neutralizing antibodies to all 20 BVD viruses. At that time, precipitating antibodies against viral-induced polypeptides of approximately 115,000; 80,000; 56,000; 48,000; 39,000; and 25,000 daltons were detected in sera from some calves. Also at that time, specificity of the antibodies for polypeptides of certain viruses was detected. At 21 days after vaccination, each calf produced neutralizing antibodies to all 20 BVD viruses. At that time, precipitating antibodies to each of the aforementioned viral induced polypeptides were detected in serum from each calf. Precipitating antibodies to viral induced polypeptides of 61,000 and 37,000 daltons were detected in samples of sera obtained from some calves at 42 days after vaccination.     

Isolation of cytopathic and noncytopathic bovine viral diarrhea virus from the spleen of cattle acutely and chronically affected with bovine viral diarrhea

Both cytopathic and noncytopathic bovine viral diarrhea virus (BVDV) were isolated from 16 of 17 bovine spleens representing 11 herds that had experienced acute BVD and from 12 of 21 bovine spleens from 1 herd affected with chronic BVD. It was concluded that isolation of cytopathic and noncytopathic BVDV from the same spleen probably indicates that an animal with a persistent, noncytopathic BVDV infection was superinfected with a cytopathic BVDV. The prevalence (greater than 70%) of 2 viruses in the spleen of cattle with acute or chronic BVD suggested that persistent infection with noncytopathic BVDV may be an important factor in the pathogenesis of BVD.