Use of an anti-GnRF vaccine to suppress estrus in crossbred Iberian female pigs.

Antibodies against GnRF elicited by vaccination with Improvac are expected to have the same effects on the gonads of female pigs as those observed in males and thus suppress estrus. The objective of this study was to evaluate whether a 3- or a 4-dose regimen of Improvac was effective in inducing and maintaining suppression of estrus in intact Iberian female pigs through 14 months of age. Sixty 18-week-old gilts were randomly assigned to one of the following three treatment groups: control (PBS injected), V3 (3-dose Improvac regimen), and V4 (4-dose Improvac regimen). Animals were tested for the presence of standing estrus in the presence of a boar three times per week until study completion at 60 weeks of age. Blood samples were regularly collected to determine the serum levels of anti-GnRF antibodies and progesterone. The weight and size of the uterus and the weight and activity of the ovaries were assessed at the time of euthanasia. For both treatment groups V3 and V4, a large reduction in the incidence of standing estrus was observed when compared to the control group (P < 0.0001). No significant differences between the V3 and V4 groups were observed. Both V3 and V4 groups had higher serum anti-GnRF antibody levels than the control group from 28 days after the first vaccination until the end of the study. In addition, both V3 and V4 groups had lower levels of progesterone than the control group from Day 112 until the end of the study (P < 0.0001 in all cases). Mean ovary weights at study end in treatment groups V3 and V4 were significantly lower (P < 0.0001) than those for the control group and not significantly different between the V3 and V4 groups. An onset of immunity of 2 weeks after the second vaccination and a long-lasting immunity of at least 20 weeks after the third vaccination were observed. In summary, both the 3-and 4-dose Improvac regimens were efficacious in reducing the incidence of standing estrus, serum progesterone levels, and the development of the uterus and ovaries.

Efficacy and safety of an attenuated live QX-like infectious bronchitis virus strain as a vaccine for chickens.

The attenuation of infectious bronchitis (IB) QX-like virus strain L1148 is described. The virus was passaged multiple times in embryonated specific pathogen free (SPF) chicken eggs, and at different passage levels samples were tested for safety for the respiratory tract and kidneys in 1-day-old SPF chickens. There was a clear decrease in pathogenicity for the respiratory tract and kidneys when the virus had undergone a large number of passages. Passage level 80 was investigated for safety for the reproductive tract in 1-day-old and 7-day-old SPF chickens. In 1-day-old chickens, 12.5% of the vaccinated birds had macroscopic lesions. No lesions were observed if the chickens had been vaccinated at 7 days of age. Passage level 80 was investigated for its ability to spread from vaccinated to non-vaccinated chickens and for dissemination in the body. The virus was able to spread from vaccinated chickens to groups of non-vaccinated chickens, and in the vaccinated birds the virus was found frequently in oro-pharyngeal and cloacal swabs. A fragment of the hypervariable region of the S1 protein of passage level 80 was sequenced and revealed nucleotide changes resulting in two amino acid substitutions. Passage level 80 was given additional passages to levels 82 and 85. Both passage levels were tested for efficacy in SPF chickens and passage level 85 was tested for efficacy in commercial chickens with maternally derived antibodies (MDA) against a challenge with QX-like strain IB D388. In both SPF chickens and chickens with MDA, the vaccines based on strain IB L1148 were efficacious against challenge.

A study on the severity and relevance of porcine circovirus type 2 infections in Dutch fattening pigs with respiratory diseases.

This study was set up to get more insights in the severity and relevance of porcine circovirus type 2 (PCV2) infections in Dutch fattening farms in an endemic PCV2-situation with no clinical signs of post-weaning multisystemic wasting syndrome (PMWS). In part A of the study, in total 29 commercial fattening farms with varying percentages of pneumonia and pleurisy at slaughter were examined. Blood samples were collected at random by cross-sectional sampling; 10 in the age of 10-12 weeks, 10 at the age of 16 weeks and 10 blood samples at the end of the finishing period (20-22 weeks of age). Serum samples were examined for the presence of PCV2 IgM and IgG antibodies and for antibodies against other porcine lung pathogens. In part B, 8 "high" and 8 "low" herds were selected. The 8 "high" herds were defined as herds having high percentages of lung lesions (pneumonia) at slaughter, and the 8 "low" herds had low percentages of pneumonia at slaughter. For both the "high" and "low" herds, 3 pigs showing signs of respiratory distress were selected for necropsy (n=48). Lung tissue samples were examined post-mortem for macroscopic and histopathological lesions, and for the presence of bacteria and viruses. The results of part A showed that, pigs at 16 weeks of age with IgM antibodies against PCV2 had a lower probability of having pleuritis at slaughter (OR 0.34, P<0.000). Pigs in the age category of 20-22 weeks, and with IgM antibodies against PCV2, also had a lower probability of having pneumonia at slaughter (OR 0.29, P=0.032). In part B lobus apicalis pneumonia, PCV2 in macroscopically unaffected lungs, Pasteurella multocida, Mycoplasma hyopneumoniae, and swine influenza viruses were all found significantly more often in "high" than in "low" pigs at autopsy. High PCV2 DNA loads (>10(4) PCV2 DNA copies/mg) were found in lungs of 14 (58%) "high", and in 7 (29%) of the "low" pigs (P=0.13). In 11 of the 19 affected lungs from "high" pigs, high PCV2 DNA loads were found in combination with one or more other lung pathogens, while this was found only in 5 of the 17 affected lungs from "low" pigs (P=0.02). This study confirms the hypothesis that PCV2 plays a role in pneumonia and pleurisy in 10-24 weeks old fattening pigs, not only in herds with a high prevalence of PMWS, but also in herds with no clinical signs of PMWS.

Assessment of respiratory herd health in weaner pigs by measuring cellular composition of bronchoalveolar lavage fluid.

Cell differentiation of bronchoalveolar lavage fluid (BALF) was compared among 11 herds having a history of recurrent respiratory disease in weaner pigs and nine herds lacking such a history. In every herd, 20 pigs aged 8-10 weeks were lavaged. The two groups differed significantly on median percentage of macrophages, neutrophils and lymphocytes, but not on white blood cell count of the BALF. Logistic regression showed the percentage of samples per herd exceeding the reference value for neutrophils of 0-8% to be the most promising parameter to assess the health status in weaner pigs.

Quantification of percutaneous absorption of metronidazole and levamisole in the fire-bellied toad (Bombina orientalis).

Spot-on application has proved to be an effective way to reach therapeutic doses of metronidazole and levamisole in fire-bellied toads. The percutaneous absorption of metronidazole and levamisole was quantified, using an aqueous solution of 1.008 mg/ml of metronidazole and an aqueous solution of 3.767 mg/ml of levamisole. High Performance Liquid Chromatography (HPLC) analysis of the percutaneous absorption revealed that of the amount applied, 75% of metronidazole and 90% of levamisole was absorbed. This resulted during 3 days of application in dosages of 23 mg/kg BW of metronidazole and 94 mg/kg BW of levamisole. Of the absorbed substances, 48% of metronidazole and 9% of levamisole were excreted in urine and faeces as unmetabolised substances.