Detection of specific IgM antibodies to infectious bronchitis virus by an antibody-capture ELISA.

The results of a new antibody-capture ELISA (alpha-IgM-IBV ELISA), specific for IgM directed against Infectious Bronchitis Virus (IBV) show that this assay is a useful tool for diagnosing IBV infections. The data include individual results of the alpha-IgM-IBV ELISA in sequential SPF chicken sera after vaccination with H120 and challenge with M41, the specificity is based on results of 499 SPF sera, and the sensitivity on sera from experimentally vaccinated and challenged birds. Also reported are ELISA results on 168 field sera originating from seven broiler flocks (24 samples per flock) collected during the acute phase of an IBV infection.

Failure of foetal protection after vaccination against an experimental infection with bovine virus diarrhea virus.

A protocol is described to measure the protection of the bovine fetus against an experimental bovine virus diarrhea virus (BVDV) infection after vaccination. Two inactivated experimental vaccines were applied twice with a 3 week interval. A mixture of three different Dutch field strains was used as challenge on mainly the 82nd day of gestation to vaccinated and unvaccinated control animals.

A comparative study of serological tests for use in the bovine herpesvirus 1 eradication programme in The Netherlands.

We compared a gB-ELISA, a gE-ELISA and a Danish test system (consisting of a blocking and an indirect ELISA) for their specificity and sensitivity to detect antibodies against BHV1. The Danish test system showed the highest sensitivity and the gE-ELISA the lowest; the gB-ELISA showed an intermediate sensitivity. If the doubtful zone (25-50% blocking) of the gB-ELISA was considered as positive (gB-ELISA+), the sensitivity almost reached that of the Danish test system.

Comparative study on four enzyme-linked immunosorbent assays and a cocultivation assay for the detection of antigens associated with the bovine viral diarrhoea virus in persistently infected cattle.

Four commercially available ELISAs for detection of antigens associated with the bovine viral diarrhoea virus in persistently infected cattle have been compared. The tests are equally specific (100%) and the sensitivity of three ELISAs is comparable with that of a conventional cocultivation assay. Performing ELISA on samples from young animals that received colostrum may yield false negative results because of interference of maternal antibodies in the tests.

Virulence and genotype of a bovine herpesvirus 1 isolate from semen of a subclinically infected bull.

A bovine herpesvirus 1 (BHV-1) isolate from the semen of a subclinically infected bull was administered to cattle by various routes to assess its virulence. Cattle that were artificially inseminated or inoculated intrapreputially did not develop clinical signs, but did transmit the virus to contact cattle. However, the isolate induced severe signs of rhinotracheitis and vulvovaginitis in cattle that were inoculated by the intravaginal, intranasal or intravenous routes, but did not infect the fetus.

[Serological study of the occurrence of L. hardjo in sheep in The Netherlands].

Sheep (3918) from 137 farms in the regions of North-, West- and Mid-Netherlands and Gelderland were serologically investigated for the presence of antibodies against Leptospira hardjo. Antibodies were detected in 3.3% of the sheep.

A subclinical infection of bulls with bovine herpesvirus type 1 at an artificial insemination centre.

A subclinical bovine herpesvirus type 1 (BHV1) infection affected bulls at an artificial insemination centre for at least six months. The virus was detected in semen samples from 43 out of 116 bulls examined; 27 of them shed virus during one consecutive period of up to 10 days and 16 shed the virus intermittently. The virus titres ranged between 10 and 100,000 TCID50/ml.

Immunity to human and bovine respiratory syncytial virus.

Human and bovine respiratory syncytial viruses resemble each other closely. During annual winter outbreaks, they cause similar respiratory tract disease in infants and calves. The disease is most severe in children and calves between 1 and 3 months old, when maternal antibodies against the virus are usually present.

A severe outbreak of respiratory tract disease associated with bovine respiratory syncytial virus probably enhanced by vaccination with modified live vaccine.

A severe outbreak of respiratory tract disease associated with bovine respiratory syncytial virus (BRSV) on a large beef-fattening farm is described. The outbreak started two days after five- to seven-month-old calves were vaccinated with a modified live BRSV vaccine. The disease ran a very severe course among five- to seven-month-old vaccinated calves, but disease was absent in eight-month-old an older non-vaccinated calves.

Development of a neutralising antibody response to an inoculated cytopathic strain of bovine virus diarrhoea virus.

Fourteen clinically healthy cattle that were persistently infected with non-cytopathic bovine virus diarrhoea virus (BVDV) and three BVDV-free cattle were inoculated with one of three cytopathic BVDV strains. Mucosal disease developed in 12 of the viraemic cattle, resulting in a moribund condition 17 to 99 days after inoculation. Two of the viraemic cattle remained clinically healthy until the end of the experiment, 14 months after inoculation.

Priming for local and systemic antibody memory responses to bovine respiratory syncytial virus: effect of amount of virus, virus replication, route of administration and maternal antibodies.

We studied the conditions under which calves can be primed for mucosal and serum antibody memory responses against bovine respiratory syncytial virus (BRSV), and the relationship between such responses and protection against the virus. Calves were primed via the respiratory tract with a low or high amount of live virus, with killed virus, or intramuscularly with live virus. Calves were challenged via the respiratory tract.

Activation of complement by bovine respiratory syncytial virus-infected cells.

Because complement activation is probably involved in the pathogenesis of as well as in recovery from the disease induced by bovine respiratory syncytial virus (BRSV), we studied the activation of complement by BRSV-infected cells in vitro in a homologous system. Binding of C3 on the surface of infected cells was measured in a biotin-streptavidin amplified ELISA, and complement-mediated lysis was measured in a 51Cr release assay. Without antibody, infected cells activated and bound more C3 than uninfected cells.

Pathogenesis of naturally acquired bovine respiratory syncytial virus infection in calves: evidence for the involvement of complement and mast cell mediators.

Indicators of immune-mediated disease were studied in calves with severe natural bovine respiratory syncytial virus infection. Although antigen and antibody were detected concurrently in most calves, immune complexes were not detected by use of immunofluorescence, ELISA, and binding of the 1q component of complement. Complement component C3, however, was observed by immunofluorescence in the cranioventral, virus-infected portion of the lungs of 19 of 25 calves.

Characterization of the F41 fimbrial antigen of enterotoxigenic Escherichia coli by using monoclonal antibodies.

We produced monoclonal antibodies (MAbs) from 23 different murine hybridoma cell lines against the F41 fimbrial antigen of bovine and porcine enterotoxigenic Escherichia coli. Cell lines were created by fusing myeloma cells and spleen cells of mice that were immunized with either purified F41 or with Formalin-killed whole cells. The specificity of the MAbs to the F41 antigen was proven by enzyme-linked immunosorbent assays (ELISAs) and radioimmunoprecipitation tests.

Analysis of the antibody response to bovine respiratory syncytial virus proteins in calves.

The antibody response in calves to natural infections with bovine respiratory syncytial virus (BRSV) was analysed by radioimmunoprecipitation assays. Antibodies to virus proteins of Mr 200K (L), 87K (G), 46K (F1), 41K (N), 35K (P), 28K and 24K (F2), 27K (M), 22K and less than 14K could be identified. Recovery of 6- to 7-month-old calves from severe BRSV-associated disease was accompanied by the development of an antibody response to the virus, which was directed mainly o the F and N proteins.

An enzyme-linked immunosorbent assay for detection of antibodies to porcine parvovirus.

An enzyme-linked immunosorbent assay (ELISA) was developed for detection of antibodies to porcine parvovirus (PPV). Antisera to PPV were raised in pigs, for which PPV grown on PK15 cells was used for primary intranasal inoculations, and PPV cultured on autologous kidney cells for booster immunisations. A competition ELISA was developed, based on the principle of a double antibody sandwich assay, using immunoglobulin fractions prepared from these sera.

Epidemiological study of bovine respiratory syncytial virus infections in calves: influence of maternal antibodies on the outcome of disease.

A prospective epidemiological survey on bovine respiratory syncytial virus (BRSV) infections in calves was carried out on 21 dairy farms during one BRSV epidemic season. Special attention was paid to the role of maternal antibodies. On 15 farms the spread of the virus was demonstrated during the investigation period and on eight farms this was accompanied by an outbreak of acute respiratory disease.

Isotype-specific ELISAs for the detection of antibodies to bovine respiratory syncytial virus.

Isotype-specific ELISAs for the detection of antibodies to bovine respiratory syncytial virus (BRSV) are described. BRSV-specific IgG1 and IgG2 were determined in indirect double antibody sandwich assays. For IgA and IgM antibody capture assays were used.

Immunoglobulin M-specific enzyme-linked immunosorbent assay for serodiagnosis of bovine respiratory syncytial virus infections.

An antibody-capture enzyme-linked immunosorbent assay (ELISA) for detection of immunoglobulin (Ig) M antibodies to bovine respiratory syncytial virus (BRSV) in cattle was developed. Monoclonal antibody to bovine IgM was used as the catching antibody. The IgM-ELISA was used, as well as a BRSV-specific IgG ELISA to determine the kinetics of IgM and IgG antibody responses to BRSV infections in cattle.

Local and systemic antibody response to bovine respiratory syncytial virus infection and reinfection in calves with and without maternal antibodies.

Enzyme-linked immunosorbent assays for the detection of immunoglobulin M (IgM), IgA, IgG1, and IgG2 antibodies against bovine respiratory syncytial virus (BRSV) were used to measure antibody responses of calves after experimental or natural infection with BRSV. Serially collected sera, lung lavage samples, nasal and eye secretions, and feces were tested for the presence of these antibodies. Lung lavage fluids and nasal secretions were further examined for the presence of virus.

Comparison of a newly developed enzyme-linked immunosorbent assay with complement fixation and neutralisation tests for serology of bovine respiratory syncytial virus infections.

An indirect double antibody sandwich enzyme-linked immunosorbent assay (ELISA) was developed for the detection and titration of serum antibodies to bovine respiratory syncytial virus (BRSV). The ELISA was compared with a complement fixation (CF) test and a test for virus neutralising antibody in serum (virus neutralisation [VN] test). Testing sera collected in dairy herds revealed the closest correlation between the results of the ELISA and the CF test with respect to BRSV antibody titres.

Gel electrophoretic analysis of polypeptides from nucleocapsids of Marek's disease virus strains and herpesvirus of turkey.

The polypeptides of nucleocapsids of Marek's disease virus (MDV) strains with different biological properties and of antigenically related herpesvirus of turkey (HVT) strains were analysed by one- and two-dimensional (1D and 2D, respectively) gel electrophoresis. Based on small differences in migration behaviour (size and charge) of a number of corresponding nucleocapsid polypeptides, the virus strains could be differentiated into three groups. The polypeptide pattern of group I, comprising the virulent MDV-strain K and the attenuated strains, HPRS-16/att and CVI988 37th passage, was composed of four major polypeptides (i.