Duration of maternally derived antibodies of porcine parvovirus in growing pigs and presence of antibodies in gilts and sows vaccinated with three different parvovirus vaccines.

While gilts and sows are regularly vaccinated against the porcine parvovirus (PPV), little is known on the presence of antibodies in vaccinated sows nor the decline of maternally derived antibodies (MDA) in their offspring. On twelve farms serum samples were taken from 180 gilts and sows vaccinated at least twice with one of three different commercial PPV vaccines. On nine farms, additional 270 serum samples were collected from growing pigs of three different age categories. All 450 samples were examined for PPV antibodies (Abs) by ELISA and haemagglutination inhibition (HI) assay. In total, 65% of all gilts vaccinated twice with either vaccine 1 or vaccine 3 were seronegative by HI assay. In each farm, there were at least three animals with high Ab titres (≥ 1:1280) indicating the presence of PPV in all twelve study farms. However, PPV DNA could not be detected in collected faecal samples. While low to moderately high Ab titres (1:10-1:640) were measured in 98% of twelve-weeks-old pigs, ELISA was only positive in 30% of the same pigs. Though, the statement on the duration of MDA may depend on the applied test, we could confirm an exponential decay of MDA. In addition, we could demonstrate that applied serological tools are insufficient for the confirmation of successful vaccination.

Discrepancy Between In-clinic and Haemagglutination-Inhibition Tests in Detecting Maternally-Derived Antibodies Against Canine Parvovirus in Puppies.

Canine parvovirus (CPV) is one of the most common causes of mortality in puppies worldwide. Protection against CPV infection is based on vaccination, but maternally-derived antibodies (MDA) can interfere with vaccination. The aim of this study was to evaluate the applicability of an in-clinic ELISA test to assess the CPV MDA in unvaccinated puppies and CPV antibodies in bitches, comparing the results with the gold standard haemagglutination inhibition (HI) test. Serum samples of 136 unvaccinated puppies were tested, along with sera of 16 vaccinated bitches. Five unvaccinated puppies were retested after vaccination. Both assays showed that the 16 vaccinated bitches had protective antibody levels against CPV. Conversely, significant discrepancies were observed for the MDA titers in unvaccinated puppies. Protective MDA titers were observed in 91.9% puppies using HI and in 40.4% by the in-clinic ELISA test, and only the latter one showed a decrease of MDA titers and percentages of protected puppies after the first weeks of age. Vaccination of five puppies with high HI and low in-clinic ELISA MDA titers resulted in seroconversion. Our results confirm the reliability of the in-clinic ELISA test in determining protective antibodies against CPV in adult dogs. Our findings also suggest that the in-clinic ELISA test kit may also be a useful tool to detect and quantify CPV MDA, thus allowing prediction of the best time to vaccinate puppies and reduction of the rate of vaccination failures due to interference by maternally-derived antibodies.

Developing Farm-Level Post-vaccination Sero-Monitoring Systems for H5N1 Highly Pathogenic Avian Influenza in an Endemically Infected Country.

Whilst the serological responses of poultry following vaccination against highly pathogenic avian influenza H5N1 has been extensively investigated under laboratory conditions, there have been fewer studies conducted in the field. This applies particularly to the endemically infected countries routinely practicing vaccination, where the combination of multiple circulating clades and/or the use of vaccines with different seed strains makes the design and interpretation of field studies especially problematic. To address this for the particular situation of layer hens in the small to medium commercial sector in Indonesia, we developed a sampling regime before and after the vaccination given to point-of-lay pullets, and assessed serological response with a panel of test antigens. This confirmed that high titres were induced in those birds vaccinated with locally produced homologous H5N1 vaccines administered two or more times, but in flocks using imported heterologous H5N2 vaccines median titres were significantly lower, and unlikely to provide protection throughout the production cycle, without additional vaccination. Comparing the HI responses against the panel of antigens enabled the detection of the flock's exposure to different vaccine antigens, and made possible the detection of mislabelled vaccine seed strains. Furthermore, we show that test antigens need not be exactly matched to assess sero-protection in well vaccinated birds. Finally our study suggests that the POL vaccination serves as a useful reference point for following cohorts of layers throughout their production cycle, and thus enabling robust vaccination field effectiveness studies.

Comparison of assays for the detection of West Nile virus antibodies in equine serum after natural infection or vaccination.

West Nile virus (WNV) mainly infects birds, horses and humans. Outcomes of the infection range from mild uncharacteristic signs to fatal neurologic disease. The main objectives of the present study were to measure serum IgG and IgM antibodies in naturally exposed and vaccinated horses and to compare results of haemagglutination inhibition test (HIT), enzyme-linked immunosorbent assay (ELISA) and plaque reduction neutralisation test (PRNT). Altogether 224 animals were tested by HIT for WNV antibodies and 41 horses were simultaneously examined by ELISA and PRNT. After primary screening for WNV antibodies, horses were vaccinated. Samples were taken immediately before and 3-5 weeks after each vaccination. McNemar's chi-squared and percent agreement tests were used to detect concordance between HIT, ELISA and PRNT. Analyses by HIT confirmed the presence of WNV antibodies in 27/105 (26%) naturally exposed horses. Sera from 57/66 (86%) vaccinated animals were positive before the first booster and from 11/11 (100%) before the second booster. HIT was less sensitive for detecting IgG antibodies. We could detect postvaccination IgM in 13 cases with IgM antibody capture ELISA (MAC-ELISA) and in 7 cases with HIT. WNV is endemic in Hungary and regularly causes natural infections. Protective antibodies could not be measured in some of the cases 12 months after primary vaccinations; protection is more reliable after the first yearly booster. Based on our findings it was not possible to differentiate infected from recently vaccinated horses using MAC-ELISA. HIT cannot be used as a substitute for ELISA or PRNT when detecting IgG, but it proved to be a useful tool in this study to gain statistical information about the tendencies within a fixed population of horses.

STUDY ON DISTRIBUTION OF Gm(2)FACTOR IN CHINESE POPULATION LIVING IN BEIJING AND DETECTION FROM BLOODSTAINS / 中国法医学杂志

The investigation on distribution of Gm(2)facotor in 269 Chinese people living in Beijing was carried out using haemagglutination inhibition test and anti-Gm(2)sera from the Biotest Diagnosis of West Germany.Results revealed that Gm(2)factors was positive in 78 cases(29%),while negative in 191 cases(71%).Gm(2)phenotyping were(?)erformed successfully in 230 bloodstains, 14 months old,made of fresh blood selected from 269 samples of known Gm(2) phenotype.Detection of Gm(2)factors was carried out in 11 crime cases.Sus- pects were excluded in 4 cases.