Colostrum from cattle immunized with a vaccine based on iron regulated proteins of Mannheimia haemolytica confers partial protection.

Passive protection afforded by colostrum from cattle vaccinated prepartum with an inactivated combination vaccine against viral pathogens and Mannheimia haemolytica (M. haemolytica) was evaluated against an experimental M. haemolytica challenge. Newborn calves were either fed colostrum from vaccinated dams or control colostrum. At approximately 3 weeks of age 24 calves were experimentally infected with M. haemolytica. Animals of both groups displayed clinical signs of respiratory disease and lung damage. The survival rate was considerably higher in calves which received colostrum from vaccinated cows. Colonies consistent with M. haemolytica were recovered in large numbers from all animals, but the geometric mean recovery was more than ten-times lower in the vaccinate colostrum fed animals. It can be concluded that maternal antibodies partly protected the calves against a severe M. haemolytica challenge.

Investigation of a dual fetal infection model with bovine viral diarrhoea viruses (BVDV)-1 and BVDV-2.

Two studies were performed in pregnant heifers to determine whether inoculation with two bovine viral diarrhoea viruses (BVDV), one BVDV-1 and one BVDV-2, inoculated separately into either nostril, results in fetal infection with both viruses. Dual transplacental infection of the fetus with BVDV-1 and BVDV-2 was observed in one case, but not consistently.

Exposure to pathogens and incidence of respiratory disease in young bulls on their arrival at fattening operations in France.

The incidence of clinical respiratory disease in 698 young beef bulls kept in 68 pens, and their exposure to respiratory pathogens after their arrival at 51 fattening operations in western France were assessed. Antibodies against bovine respiratory syncytial virus (BRSV), bovine herpesvirus type 1 (BHV-1), Mannheimia haemolytica and Mycoplasma bovis were measured by ELISA. The incidence risk of respiratory disease was 18.5 per cent during the first six weeks. Cases occurred in 37 of the 68 pens, and in these pens 30.9 per cent of the bulls were affected. Their exposure to BHV-1 was very limited. When they arrived a high proportion of the bulls were seropositive to M haemolytica and a high proportion seroconverted to BRSV, M haemolytica and M bovis within the first six weeks. The risk of incidence of respiratory disease was lower in the pens in which the bulls had been vaccinated against M haemolytica. Higher proportions of the bulls were affected in pens in which small proportions of the bulls were seropositive to M haemolytica or BRSV on arrival, and in pens in which high proportions of the bulls were exposed to M haemolytica or BRSV during the first six weeks.

Efficacy of a live bovine herpesvirus type 1 marker vaccine under field conditions in three countries.

The performance of a live marker vaccine for bovine herpesvirus type 1 (bhv-1) was studied in the field in three European Union countries with different farming conditions. The progress in the eradication of the virus was followed in a large herd in Germany and one in Italy, and a major serological survey involving 147 farms was conducted in Hungary. Commercial batches of the same vaccine were used in all three studies. The herds were vaccinated according to agreed protocols and the animals' bhv-1 antibody status was determined at local institutes by using commercial glycoprotein B (gB)- and glycoprotein E (gE)-elisas. In all three studies, the seroprevalence of bhv-1 gE decreased progressively. Given the starting conditions and the long duration of the studies, reactivation events and virus circulation would have been more likely to have occurred if the herds had not been vaccinated.

Compatibility of a live infectious bovine rhinotraheitis (IBR) marker vaccine and an inactivated bovine viral diarrhoea virus (BVDV) vaccine.

The target animals and vaccination regimes for vaccines against the bovine rhinotracheitis (IBR) and the bovine viral diarrhoea virus (BVDV) are very similar. Therefore, we have compared different schedules for the combined use of a live IBR marker vaccine and an inactivated BVD vaccine. The neutralizing antibody response against BVDV did not reveal any differences between the group vaccinated only with the BVD vaccine and the groups that were vaccinated simultaneously (together in the same syringe) or concurrently (two separate injections) with the IBR marker vaccine at the first or second dose and the third dose of the BVD vaccine. Likewise, the bovine herpesvirus 1 (BHV-1) neutralizing antibody titres did not exhibit any negative effect by the simultaneous or concurrent use of the two products as compared to the single IBR marker vaccination. These results indicate that the two vaccines can be applied at the same day for the first or second dose of the BVD basic vaccination and then at the booster vaccinations (third dose onwards).

Evaluation of the induction of NS3 specific BVDV antibodies using a commercial inactivated BVDV vaccine in immunization and challenge trials.

In order to evaluate whether cattle vaccinated with an inactivated vaccine against bovine viral diarrhoea virus (BVDV) can be differentiated serologically from BVDV infected animals, two different aspects were investigated. Firstly the antibody response against non-structural proteins (NS) was measured after multiple vaccinations of cattle with a single or double dose of a commercially available inactivated BVDV vaccine. In a second study, the animals were first vaccinated with the product, and then infected with BVDV. The antibody response was determined in four different commercial ELISA systems. It can be concluded, that the inactivated BVD vaccine exhibits properties of a marker vaccine when an appropriate antibody NS3 ELISA is applied: after vaccination NS3-specific antibody levels are low or undetectable, but the vaccination does in the present study not show any interference with the development of antibodies against NS3 after subsequent field virus infection.

Incidence of BVDV1 and BVDV2 infections in cattle submitted for necropsy in Northern Germany.

The incidence of bovine viral diarrhoea virus (BVDV) 1 and 2 infections was determined in calves, young cattle and older cattle with signs of mucosal disease (MD) submitted for necropsy to three laboratories in Northern Germany between June 2000 and May 2001. At necropsy, tonsils, retropharyngeal lymph nodes, mesenteric lymph nodes, ileal Peyer's patch and spleen were collected and examined by immunohistochemistry and virus isolation. From 311 animals examined, 30 (9.6%) were positive for BVDV. All viral isolates were typed by polymerase chain reaction after reverse transcription using species-specific primers and determined to be BVDV1. Based on the distribution of lesions and viral antigen, animals with MD, persistent infection (PI) and acute, transient infection could be distinguished. Twelve of the positive animals had characteristic signs of MD: severe diarrhoea, erosive to ulcerative lesions throughout the digestive tract and severe depletion of all lymphoid tissues. Viral antigen was present in all tissues and cell types, but particularly in depleted lymphoid follicles and altered epithelium. In seven calves, viral antigen was detectable in all tissues and cell types, but lesions were mild or missing. This is typical for PI. The remaining 11 calves most likely represent animals with acute, transient infection. Distribution of antigen was more variable, predominantly restricted to lymphoid follicles and often not seen in all tissues examined. Clinical findings were combined bronchopneumonia and enteritis. The detection of BVDV1 in young calves with pneumonia and enteritis emphasizes the importance of BVDV1 and not only BVDV2 for severe respiratory and enteric diseases of calves.

Bovine viral diarrhea virus with deletions in the 5'-nontranslated region: reduction of replication in calves and induction of protective immunity.

Bovine viral diarrhea virus (BVDV) with deletions in the 5'-nontranslated region (5'-NTR) were tested for their suitability as live BVD vaccines. Firstly, the genetic stability of the mutants was established by culturing over 15 passages in bovine cells. Secondly, two deletion mutants and the parent strain CP7-5A were characterised with respect to in vivo replication competence, attenuation and induction of protective immunity against BVDV. Naïve calves (n = 5 per group) were inoculated with mutants d2-31 and d5-57 or CP7-5A and 5 weeks later, a challenge with the BVDV type 1 strain New York was performed. The mutants were found to be genetically and phenotypically stable. Moreover, the results indicate that the mutants were attenuated with regard to effects including pyrexia and drop in leucocyte counts. Infection with the mutants induced moderate to high titers of BVDV neutralizing antibodies and completely prevented viremia after challenge infection with a heterologous BVDV strain. Taken together, the 5'-NTR deletion mutants combine a good safety profile with good efficacy and are therefore well suited as candidate live vaccines.

Bovine viral diarrhoea virus antigen in foetal calf serum batches and consequences of such contamination for vaccine production.

A protocol to test foetal calf serum (FCS) for contamination with bovine viral diarrhoea virus (BVDV) is described. Following this protocol, which combines cell culture methods and detection of pestivirus RNA, seven batches of FCS were tested. Infectious BVDV was detected in four of those batches. One of the remaining batches contained a relatively high number of non-infectious BVDV particles. A sample of this batch was formulated with aluminium hydroxide and aluminium phosphate as adjuvant into an experimental vaccine preparation. This product was injected twice into BVDV seronegative cattle with a 4 week interval. Blood samples taken 4 weeks after the second application were negative for BVDV specific antibodies. Our data stress that detection of BVDV RNA is not sufficient for a complete risk assessment on FCS. Discrimination between infectious and non-infectious BVDV is essential. This can only be achieved by cell culture methods.

Leukopenia and thrombocytopenia in pigs after infection with bovine viral diarrhoea virus-2 (BVDV-2).

The aim of this study was to investigate whether bovine viral diarrhoea virus-2 (BVDV-2) is pathogenic for pigs, which organs become infected and whether or to which extent the virus is excreted into the environment. Ten pigs were observed for clinical reactions after infection with a BVDV-2 strain, that has been shown to be pathogenic in calves under experimental conditions. Samples were taken to monitor thrombocyte and leukocyte counts as well as antibody development. Post mortem examinations were performed at 7, 11 and 27 days after infection. Tissue samples were collected for virus isolation, histological and immunohistological examination. All ten pigs became infected and BVDV could be re-isolated from the lymphocytes, the plasma and different lymphatic organs. The infection passed clinically inapparent, apart from a slight increase in body temperature in some animals. Some animals developed a slight leukopenia and/or thrombocytopenia. There were no macroscopic or histological lesions observed that could specifically be related to the inoculation of BVDV-2. With respect to all parameters studied, the infection and the consequences thereof were clearly less pronounced in pigs as compared to cattle, the natural host. Our results indicate, that pigs infected with BVDV-2 might develop antibodies that cross-react in tests for antibodies against classical swine fever virus.

Serum-free produced Bovine Herpesvirus type 1 and Bovine Parainfluenza type 3 virus vaccines are efficacious and safe.

The studies described in this report were performed to determine, whether it is possible to produce live virus vaccines without serum or fractions thereof used during any cell or virus passage, thus completely serum-free. Two viruses were included in the experiments: Bovine Herpesvirus 1 (BHV-1) and Bovine Parainfluenza type 3 virus (PI3). Both viruses were found to grow to satisfactory titers, and to be stable after freeze-drying and subsequent storage at temperatures of +4 degrees C and -20 degrees C for at least one year. Moreover, a vaccine containing serum free produced BHV-1 was tested in a vaccination-challenge experiment. For comparison, a vaccine batch with BHV-1 grown in serum-containing cell culture medium was included in the study. Both vaccine preparations performed equally well and both met the strict requirements as laid down in the European Phamacopeia. Moreover, in two separate experiments the safety of serum-free produced BHV-1 and PI3 after overdose and repeated administration even in very young calves and even after four administrations has been demonstrated. This report is the first, which to our knowledge demonstrates the safety and efficacy of serum-free produced live vaccines in the target animal as well as the stability of these products.

An inactivated bovine virus diarrhoea virus (BVDV) type 1 vaccine affords clinical protection against BVDV type 2.

This study was designed to answer to two distinct questions. Firstly, is it possible to reproduce clinical signs of acute bovine virus diarrhoea virus (BVDV) type 2 infection including signs of haemorrhagic disease under experimental conditions in cattle at 20 weeks of age? Secondly, what is the extent of the protection afforded by vaccination with an inactivated BVDV type 1 vaccine against BVDV type 2 infection? Calves were vaccinated at 12 and 16 weeks of age with a commercially available inactivated BVDV type 1 vaccine (Bovilis BVD). At 20 weeks they were challenge infected with BVDV type 2 virus together with unvaccinated control calves. The unvaccinated animals developed typical signs of respiratory disease, diarrhoea with erosions and haemorrhages along the whole length gastro-intestinal tract, and depletion of lymphocytes in lymphatic organs. These signs were either absent or markedly less severe in the vaccinated animals. The beneficial effects of vaccination were most striking in the haematological parameters thrombocytopenia and leukopenia. It can be concluded that vaccination with Bovilis BVD affords cross-protection against clinical effects of a challenge-infection with heterologous type 2 BVDV.

Early immunity induced by a glycoprotein E-negative vaccine for infectious bovine rhinotracheitis.

Four groups of calves were vaccinated with a glycoprotein E-negative vaccine for infectious bovine rhinotracheitis. Two groups of calves were vaccinated intramuscularly and challenged with a wild-type virus 14 and seven days after being vaccinated. The other two groups were vaccinated intranasally and similarly challenged after four and three days; an unvaccinated control group was also challenged. All four vaccination schedules reduced the incidence of clinical signs and the excretion of wild-type virus, and these reductions occurred as early as three days after the intranasal vaccination even in the absence of neutralising antibodies. Because of its marker characteristics, vaccination with this vaccine would not interfere with the detection of infected cattle during an outbreak, and it should therefore provide a useful tool for emergency vaccination campaigns.

Intestinal manifestations of experimental SIV-infection in rhesus monkeys (Macaca mulatta): a histological and ultrastructural study.

Intestinal lesions were studied in 32 rhesus monkeys experimentally infected with different strains of simian immunodeficiency virus SIVmac (251/32H, 251/32H-SPL and 251/MPBL) by light microscopy, transmission and scanning electron microscopy. A spectrum of primary and secondary manifestations of SIV-infection were detected. Primary changes included 'SIV-enteropathy' in 12 monkeys and virus-induced syncytial giant cell formation (GCF) of the intestine in two animals. A primary virus-induced enteropathy occurred both as only histologically visible 'SIV-enteropathy' and as 'AIDS-enteropathy' accompanied by clinical signs of enteritis. Secondary opportunistic infections (Balantidium coli, Cryptosporidium, Trichuris, Trichomonas, Spironucleus, Mycobacteria and Cytomegalovirus) were identified in 27 animals and three monkeys developed malignant lymphomas involving the intestinal tract. Compared to intestinal lesions in HIV-infected patients, differences were found concerning the incidence of GCF and the range of opportunistic infections, with cryptosporidium, cytomegalovirus and mycobacteria occurring in both SIV-infected macaques and AIDS patients. The present observations revealed that SIV-infected rhesus monkeys provide an excellent model both for studies on the pathogenesis of HIV-enteropathy and opportunistic infections and for the development of therapies against cryptosporidial, cytomegalovirus and mycobacteria infection. Comparison of three SIV-strains revealed differences in primary and secondary lesions observed: SIVmac251/MPBL was correlated with severe primary SIV-induced pathologic changes and SIVmac251-SPL-infected animals showed a higher incidence of malignant lymphomas.