Vaccination of pregnant sows against transmissible gastroenteritis with two attenuated virus strains and different inoculation routes.

Two attenuated transmissible gastro-enteritis (T.G.E.) virus strains were used for vaccination experiments in sows. Four different experiments were carried out (see Table 1). In each experiment, 9 sows were vaccinated during pregnancy and 3 sows served as controls. They were kept together in one farrowing house. The sows were due to farrow at about the same time. The sows and their litters were challenged shortly after farrowing by exposing 3 piglets of 2 controls litters to virulent TGE virus. The following vaccination schedules were used (see Table 1): twice intramuscularly with TGE-vac (a commercially available TGE-vaccine), one oral administration followed by an intramuscular vaccination with an attenuated TGE Purdue (Pu) strain, twice orally with Pu strain in enteric coated capsules, and one direct intra intestinal administration followed by 2 intramuscular vaccinations or 3 intramuscular vaccinations with the Pu strain. All sows, except most of those treated with enteric coated capsules, seroconverted demonstrably (Table 2). The geometric mean seroneutralization (SN) titer log 2 varied from 4.1 to 7.5 after the first vaccination and from 7.6 to 10 after the second vaccination. None of the vaccination schedules resulted in an effective lactogenic immunity. The morbidity in the piglets was 100% within 3 to 5 days after challenge. The mortality rate varied from 44 to 80% in litters from vaccinated sows and from 71 to 100% in litters from control sows (see Table 3). Clinical signs were observed in 33.3% of the control sows and in 36% of the vaccinated sows. No correlation was found between the titer of SN antibodies in the sera of the piglets and their survival rate (Table 4). A rapid decrease in antibody concentration was observed, during the first week of lactation in milk samples collected from 4 orally and intramuscularly vaccinated sows (Table 5).

Indirect fluorescence antibody studies of porcine cytomegalo virus infections in the Netherlands.

Sera from 683 pigs of 41 swine herds with clinical atrophic rhinitis (AR), from 477 pigs of 37 herds with no AR history, from 267 breeding sows and breeding boars for slaughtering, from 22 boars at an artificial insemination centre, and from 103 SPF pigs were tested for the presence of antibodies to porcine cytomegalo virus (PCMV). The herds examined were spread all over the Netherlands. For the presence of antibodies to PCMV the indirect fluorescence antibody test was used. To obtain the antigen, the PCMV had been grown in pig lung macrophage cultures in Petri dishes for 10--12 days. These macrophages were dropped into the wells of slides. The serum dilution 1:20 of all the 103 sera from SPF pigs were negative, but 93 per cent of the other sera were positive. No marked differences were found between swine herds with clinical atrophic rhinitis and herds with no AR history. The FA titres in both types of herds seem to be at a comparable level.

Indirect fluorescence antibody studies of porcine cytomegalo virus infections in the Netherlands.

Summary Sera from 683 pigs of 41 swine herds with clinical atrophic rhinitis (A R), from 477 pigs of 37 herds with no A R history, from 267 breeding sows and breeding boars for slaughtering, from 22 boars at an artifical insemination centre, and from 103 SPF pigs were tested for the presence of antibodies to porcine cytomegalo virus (PCMV). The herds examined were spread all over the Netherlands. For the presence of antibodies to PCM V the indirect fluorescence antibody test was used. To obtain the antigen, the PCMV had been grown in pig lung macrophage cultures in Petri dishes for 10-12 days. These macrophages were dropped into the wells of slides. The serum dilution 1:20 of all the 103 sera from SPF pigs were negative, but 93 per cent of the other sera were positive. No marked differences were found between swine herds with clinical atrophic rhinitis and herds with no A R history. The FA titres in both types of herds seem to be at a comparable level.

Vaccination of pregnant sows against transmissible gastroenteritis with two attenuated virus strains and different inoculation routes.

Summary Two attenuated transmissible gastro-enteritis (T. G. E.) virus strains were used for vaccination experiments in sows. Four different experiments were carried out (see Table 1). In each experiment, 9 sows were vaccinated during pregnancy and 3 sows served as controls. They were kept together in one farrowing house. The sows were due to farrow at about the same time. The sows and their litters were challenged shortly after farrowing by exposing 3 piglets of 2 control litters to virulent TGE virus. The following vaccination schedules were used (see Table 1): twice intramuscularly with TGE-vac (a commercially available TGE-vaccine), one oral administration followed by an intramuscular vaccination with an attenuated TGE Purdue (Pu) strain, twice orally with Pu strain in enteric coated capsules, and one direct intra intestinal administration followed by 2 intramuscular vaccinations or 3 intramuscular vaccinations with the Pu strain. All sows, except most of those treated with enteric coated capsules, seroconverted demonstrably (Table 2). The geometric mean seroneutralization (SN) titer log 2 varied from 4.1 to 7.5 after the first vaccination and from 7.6 to 10 after the second vaccination. None of the vaccination schedules resulted in an effective lactogenic immunity. The morbidity in the piglets was 100% within 3 to 5 days after challenge. The mortality rate varied from 44 to 80% in litters from vaccinated sows and from 71 to 100% in litters from control sows (see Table 3). Clinical signs were observed in 33,3% of the control sows and in 36% of the vaccinated sows. No correlation was found between the titer of SN antibodies in the sera of the piglets and their survival rate (Table 4). A rapid decrease in antibody concentration was observed, during the first week of lactation in milk samples collected from 4 orally and intramuscularly vaccinated sows (Table 5).

[Vaccination using an inactivated vaccine on a pig-breeding farm infected with the virus causing Aujeszky's disease (author's transl)]. / Vaccinatie met een geïnactiveerd vaccin op een met het virus van de ziekte van Aujeszky besmet varkensfokbedrijf.

When Aujeszky's disease was detected on a large pig-breeding farm, all normal sows and boars were vaccinated with an ethyl-ethylene-imine (EEI) vaccine produced in the Bundesforschungsanstalt für Viruskrankheiten der Tiere (Federal Research Institute for Viruses Diseases in Animals) in Tübbingen, Western Germany. The vaccine contained DEAE dextran as an adjuvant. The vaccine was inoculated twice by intramuscular route at a three weeks' interval, 5 ml. being inoculated at one time. Hyperimmune serum was inoculated in young pigs. In addition, hygienic procedures were adopted, consisting in disinfection and isolation. The disease was successfully controlled within eight weeks. Sows which developed Aujeszky's disease showed hardly any symptoms suggesting lesions of the central nervous system. Pulmonary lesions were the outstanding clinical feature. The semen quality of the affected male swine had markedly deteriorated. This was resorted to normal, however, within from five to ten weeks. The incidence of abortion and piglet mortality were low. In view of the results of virological and serological studies, it was concluded that the persistence of this strain of virus (causing Aujeszky's disease) was very slight.

[An atypical form of Aujezky's disease after vaccination (author's transl]. / Een atypische vorm van de ziekte van Aujeszky bij de hond na vaccinatie

Four atypical case of Aujezky's disease in dogs are described. Two weeks before the outbreak of the disease, the dogs had been vaccinated with a live tissue culture vaccin, based on the Bartha strain. By culturevirus (cytopathogenic effect) the Bartha vaccin was identified and a vaccination reaction was proved. Vaccination with this must be discouraged.

A comparative study of the neutralisation test and the indirect fluorescent antibody technique for the detection of antibodies to the virus of Aujeszky in pig sera.

A microneutralisation test and an indirect fluorescent antibody technique for the detection of antibodies to Aujeszky-virus in pig sera are described. All the sera were tested with both techniques and the results were compared. Serum dilutions of less than 1:32 which produced a positive reaction in the indirect FAT were considered nonspecific. Bij contrast, all neutralising antibody titers of less than 1:8 gave nonspecific reactions in the indirect FAT.

Studies on a virus isolated from the brain of a parakeet (Neophema sp).

Haemagglutinating viruses were isolated from Australian parakeets and from aviary birds of the order Passeriformes. In all cases the affected birds showed symptoms of disease of the nervous system. One of the isolates, 449, has the physico-chemical and biological properties of the paramyxoviruses. Comparative serological and animal-experimental investigations suggested that this isolate could be a deviating strain of Newcastle disease virus.

[Meningo-encephalitis in mink caused by NCD virus (author's transl)]. / Meningo-encephalitis bij de nerts (mustela vison), veroorzaakt door het psuedovogelpest-virus

In 1970-1972 a great number of mink died of a meningo-encephalitis in the Netherlands. The results of the detailed microbiological and histopathological examination pointed to infection by NCD virus as the cause of the mortality. During the isolation of the NCD virus in embryonated hen eggs the haemagglutinating properties were extremely weak and incomplete; the normal haemagglutination of the NCD virus was not found until the mink isolates had been passed through chickens. Transmission experiments revealed that the pathogenicity of the NCD virus was relatively low in mink after i.c. and i.m. infection, very young mink being the most susceptible. The mink were doubtlessly infected with the NCD virus bij feeding with offal of infected poultry. There was in fact quite a high incidence of Newcastle disease on Dutch chicken farms in 1970-1972.

Bovine adenoviruses. A review of vaccination experiments.

The adenoviruses are one of the virus groups involved in the respiratory disease complex in young cattle and are one of the causes of great economic losses. A statement of the identified bovine adenoviruses and their pathogenicity in cattle is given. The number of eight bovine serotypes is expected to increase as research continues and unidentified strains are compared with recognized types. The vaccination trials which have been done until now with bovine adenovirus vaccines have been limited to the examination of the internal humoral response. The ability to resist challenge with homologous or heterologous virus has never been investigated. The cell-mediated immunity has not been studied at all and the secretory local immunity to a very limited degree. Inactivated bovine adenovirus vaccines have been shown to stimulate the antibody production in young calves. On the whole, oil adjuvant vaccines are most effective both in respect of initial antibody response and in duration of demonstrable antibodies. The disadvantages of live bovine adenovirus vaccines are discussed.