High levels of maternally derived antibodies do not significantly interfere with the development of humoral and cell-mediated responses to Porcine circovirus 2 after intradermal vaccination.

BACKGROUND: Vaccination of pigs against PCV2 is usually performed around weaning when animals still have maternally derived antibodies (MDA). The present study aimed to assess the possible interference of MDA in the development of the PCV2-specific immune response after vaccination of commercial weaners. For this purpose, a PRRS-negative 600-sow farrow-to-finish farm was selected. Half of the sows were vaccinated and revaccinated with Porcilis® PCV ID against PCV2 7 and 3 weeks before farrowing. After farrowing, piglets were tested by AlphaLisa to select 72 animals with high and low levels of MDA. Groups were further subdivided and vaccinated intradermally with Porcilis® PCV ID at 21 or 28 days of age. Unvaccinated controls were also included. Animals were followed afterward for 42 days to examine the development of PCV2-specific antibodies and interferon-γ secreting cells (IFN-γ SC). RESULTS: The average titres of antibodies of the groups vaccinated in the presence of low or high MDA levels were similar at 28 and 42 days post-vaccination while in the controls the titres declined throughout the observation period. Results of vaccinating at 21 or 28 days of age were equivalent with regard to antibody development. Regarding the IFN-γ SC, vaccinated animals produced significant frequencies of IFN-γ SC by day 28. Again, no differences were observed between the groups with high or low antibody levels. CONCLUSION: High levels of MDA did not interfere with the development of humoral and cell-mediated responses to Porcine circovirus 2 after intradermal vaccination at 21 or 28 days of age.

Slaughterhouse Visual and Palpation Method for Estimating the Economic Damage of Porcine Proliferative Enteropathy (PPE).

BACKGROUND: Ileitis is a wasting disease of pigs. Clinical symptoms are diarrhea in growing pigs, wasting and reduced performance. Ileitis is ubiquitous in pig producing countries all around the world. It is estimated that the economic losses caused by the disease are USD 4.65 per fattening pig, and American pig farmers lose USD 56.1 million annually. It has become necessary to develop a slaughterhouse ileitis monitoring method that is simple, feasible to perform at modern slaughter lines, leads to immediate results and is cost effective. The practical experiences of applying the method are presented below. METHODS: Our studies were performed on pig herds and slaughterhouses in Central European countries (Hungary, Romania, Poland, Croatia, and Slovakia). Experiences were evaluated based on visual and palpation. The results of our investigations were evaluated by a scoring method. Authors made histological and immunohistochemical examinations of investigated ileums. The hypothetic economic losses due to the disease in each farm were determined by estimating the loss of profit according to Holtkamp's presentation in 2019. RESULTS: The essentials of the method we have developed are: it can be performed during slaughterhouse processing, it does not interfere with or make it impossible to carry out normal technological processes, and the results of the procedure are correlated with the results of other laboratory diagnostic tests for ileitis (histology, immunohistochemistry, herd serology, fecal PCR). It is noteworthy that the results of the method can be used to immediately estimate the impact of Lawsonia intracellularis infection on the performance of the herd from which the slaughter animals come. CONCLUSION: Using the results of the slaughtered pigs' visual and tactile examination at the slaughterhouse, the magnitude of the loss caused by Lawsonia intracellularis infection can be estimated quickly and accurately, and the return on investment of the strategy to be applied can be accurately planned.

Examination on the Occurrence of Coinfections in Diagnostic Transmittals in Cases of Stillbirth, Mummification, Embryonic Death, and Infertility (SMEDI) Syndrome in Germany.

The stillbirth, mummification, embryonic death, and infertility (SMEDI) syndrome is most commonly associated with porcine parvovirus 1 (PPV1) infections. Little is known about the occurrence of coinfections with SMEDI-associated pathogens and the associations among these pathogens. In our study, we included 40 SMEDI-affected litters from 18 different farms. In total, 158 out of 358 available fetuses from diagnostic transmittals were selected by systematic random sampling and examined for PCV2, PCV3, PPV1, and Leptospira spp. by q-PCR. Results from diagnostic materials showed the following results: in eleven farms, PCV2 was present; in nine farms, PPV1 was present; in five farms, PCV3 was present; and in two farms, Leptospira spp. was present. The detection of Leptospira spp. was significantly associated with a PCV2 coinfection (OR: 26.3; p < 0.001). PCV3 positivity resulted in a reduced probability of detecting PCV2 in the corresponding fetus (OR: 0.078; p = 0.008). Fetal maceration was associated with Leptospira spp. detection (OR: 8.6; p = 0.003), whereas mummification (p = 0.047), reduced crown-rump length (p < 0.001), and bodyweight (p = 0.001) of fetuses were significantly associated with PPV1 and PCV2 coinfection and thus, presumably, a shorter time to death after infection, indicating an enhanced negative effect on the development of fetuses with PCV2 + PPV1 coinfection.

Explorative Field Study on the Use of Oral Fluids for the Surveillance of Actinobacillus pleuropneumoniae Infections in Fattening Farms by an Apx-Real-Time PCR.

Oral fluids (OFs) represent a cost effective and reliable tool for surveillance purposes, mostly regarding viruses. In the present study, we evaluated the suitability of OFs for surveillance purposes concerning Actinobacillus (A.) pleuropneumoniae infections in fattening pigs under field conditions. OFs were examined with an Apx-toxin real-time PCR that detects the genes encoding for Apx I-, Apx III-, and Apx IV-toxin. For this purpose, we conducted a pen-wise collection of OFs over one fattening period from fattening pigs of two farms (farm A and B) with a known history of A. pleuropneumoniae infection. Lung lesions were determined at slaughter to estimate the extend of pulmonary lesions and pleural affection. Apx III- and Apx IV-toxin DNA were present in the OFs of both farms whereas Apx I-toxin DNA was present on farm A only. We were able to detect Apx I-, Apx III-, and Apx IV-toxin DNA in different patterns directly after introduction of the new pigs in the farms and over the entire study period. In summary, or results indicate the suitability of OFS for the early detection and surveillance of A. pleuropneumoniae in fattening farms.

Correlation of Lawsonia intracellularis positivity in quantitative PCR and herd factors in European pig herds.

BACKGROUND: Lawsonia intracellularis is causing diarrhea, poor growth and sudden death in pigs. It can be found in most pig populations leading to large economic losses worldwide. Many potential risk factors for the occurrence of disease or seropositivity have been described. The current study therefore focused on herd characteristics in European countries associated with direct detection of the pathogen determined by quantitative polymerase chain reaction. RESULTS: A median number of less than 30 nursery pigs per pen was correlated to less positive nursery pigs (p < 0.01) and generally less samples positive per herd (p < 0.05) as well as a lower median of genome equivalents determined per herd (p < 0.05). Routine use of zinc oxide at/ around weaning, which was mentioned by 41.0% of all farmers, was correlated to higher number of positive nursery pigs (p < 0.01) as well as higher median genome equivalents determined per herd (p < 0.05). Slatted flooring of more than 78.0% of the surface in nursery units was correlated to lower number of positive animals (p < 0.05) and a lower median of genome equivalents per herd (p < 0.05). A weight of more than 7.8 kg at weaning was correlated to a higher number of positive growing pigs (p < 0.05) as well as general higher number of positive samples/ herd (p < 0.01). CONCLUSIONS: Weaning and subsequent accommodation of nursery pigs seem to be of particular importance in prevention of infection with Lawsonia intracellularis and the spread of the pathogen within the herd.

Serologic response and safety to vaccination against avian influenza using inactivated H5N2 vaccine in zoo birds.

Due to the spread of the H5N1 highly pathogenic strain of avian influenza virus across Europe, a preventive vaccination occurred in early 2006 among 135 French zoologic institutions. Approximately 25,000 birds were vaccinated with a H5N2 inactivated vaccine. Among them, 4,369 birds were monitored by members of Association Francophone des Vétérinaires de Parc Zoologique regarding safety issues of the vaccination protocol. A total of 1,686 blood samples were collected before the first injection (n = 255), at the time of booster (n = 463), 60 day after the booster (n = 514), and 180 day (n = 229) and 330 day (n = 217) after the initial injection. Thus, sera of 126 species representing 15 different avian orders were tested using the hemagglutinin inhibition assay to evaluate seroconversion and the long-term serologic profile of selected anti-H5 antibody. Safety was considered satisfactory in all orders, and there were no deleterious effects on large-volume injection/body weight ratio. After the second injection, 71% of the birds developed a titer > or =32, with a mean titer of 558. Titers then decreased in all birds, with 42% of the remaining birds having a titer > or =32 at day 180 and only 26% at day 330. Results demonstrated that a booster 42 days after initial vaccination was mandatory to raise the titer above 32, considered to be the protective level in poultry, and to increase the number of seroconverted birds. Differences in the serologic responses among the orders and species of birds were detected and could be linked with the variation of vaccine dose injected per body weight or with species-specific immune response. The protocol for additional campaigns will be adjusted for some bird orders through the increase of injected dose or a half yearly booster to sustain better titers over the year. Vaccination is a useful tool, together with biosecurity, that should always be used as a primary method of preventing and controlling avian influenza outbreaks.

Prevalence of Lawsonia intracellularis in pig herds in different European countries.

BACKGROUND: Lawsonia intracellularis causes large economic losses in the pig industry worldwide. Pigs suffer from reduced daily weight gain, poor feed conversion ratio and increased mortality. The number of affected animals and herds in Europe remains unknown. This study will provide an overview of the prevalence of Lawsonia intracellularis in herds with a history of diarrhoea in different European countries and thereby identify country specific differences. RESULTS: Out of the 144 herds sampled in Germany, Denmark, Spain, the Netherlands and the United Kingdom, 90.3% (79.2-100.0%) contained at least one positive faecal sample on quantitative polymerase chain reaction (qPCR). Of the 6450 nursery, growing and finishing pigs of the previously mentioned herds, 26.2% (15.9-41.5%) of the animals were tested positive in faecal samples. Enzyme linked immunosorbent assay (ELISA) results of 60 herds were 91.7% (70-100%) positive. The percentage of positive samples in these 1791 blood samples was 31.6% (20.3-51.0%). Herd prevalence did not differ significantly by qPCR or ELISA. Significant differences between the countries were found regarding: Within-herd prevalence- qPCR: Samples from Denmark were more often positive than samples of Spain or the United Kingdom. Within-herd prevalence- ELISA: Samples from Denmark were more often positive than samples from Spain and the Netherlands. Affected age category- qPCR: Nursery pigs in Denmark were more often positive and shed more genome equivalents than nursery pigs in the other countries. Concentration of detected genome equivalents- qPCR: The concentration of genome equivalents from Lawsonia intracellularis in herds in Denmark was higher compared to all other countries. CONCLUSION: A widespread of Lawsonia intracellularis in the six European countries was confirmed, whereby a large part of the positive animals only excreted small amounts of genome equivalents. Country specific differences were found with Denmark in particular diagnosing more Lawsonia intracellularis then the other countries. Herd data collected in this study needs to be analysed to get more information about possible reasons for the differences found between the countries.

The consistency approach for the quality control of vaccines.

Current lot release testing of conventional vaccines emphasizes quality control of the final product and is characterized by its extensive use of laboratory animals. This report, which is based on the outcome of an ECVAM (European Centre for Validation of Alternative Methods, Institute for Health and Consumer Protection, European Commission Joint Research Centre, Ispra, Italy) workshop, discusses the concept of consistency testing as an alternative approach for lot release testing. The consistency approach for the routine release of vaccines is based upon the principle that the quality of vaccines is a consequence of a quality system and of consistent production of lots with similar characteristics to those lots that have been shown to be safe and effective in humans or the target species. The report indicates why and under which circumstances this approach can be applied, the role of the different stakeholders, and the need for international harmonization. It also gives recommendations for its implementation.