This study investigated Mycoplasma hyopneumoniae colonisation and lung lesions at slaughter in pigs from vaccinated (V) and non-vaccinated (NV) sows, in two herds (A and B). In each herd, two sow batches were V against M. hyopneumoniae with a commercial bacterin at six and three weeks before farrowing and two sow batches remained NV. From each sow batch, laryngeal swabs were collected from the litters of five primiparous sows at weaning and seven days post-weaning. All samples were tested for M. hyopneumoniae by nested PCR. In total, 488 piglets were sampled. At slaughter, the extent of Mycoplasma-like pneumonia lesions (lung lesion score (LLS)) was assessed. The colonisation rates with M. hyopneumoniae at weaning and seven days post-weaning were (V-A=14.2, NV-A=20.0 (P=0.225); V-B=0.9, NV-B=0.8 (P=0.948)) and (V-A=0.8, NV-A=7.0 (P=0.039); V-B=1.8, NV-B=2.5 (P=0.738)), respectively. The average LLS (in per cent) was V-A=15.5, NV-A=26.4 (P=0.021); V-B=9.7, NV-B=8.4 (P=0.541). In conclusion, in herd A, with a substantially higher level of piglet colonisation at weaning than herd B, offspring from V sows had a significantly lower colonisation rate seven days post-weaning and a significantly lower LLS at slaughter compared with the offspring of the NV sows. This implies that sow vaccination might be useful for control of M. hyopneumoniae infections, although significant results may not be achieved at all times (such as in herd B).

Porcine reproductive and respiratory syndrome virus (PRRSV) is a major pathogen of swine. Due to genetic variation between the European and the US genotype as well as within both genotypes detection of PRRSV is a diagnostic challenge. This paper reports on a ring test to compare different established reverse transcriptase polymerase chain reaction methods applied routinely in 16 different laboratories in Germany. Three different sets of samples were sent to the laboratories which were to be analysed as follows: (i) basis package: detection of PRRS (yes/no); (ii) differentiation package I: differentiation of EU and US genotypes; and (iii) differentiation package II: differentiation of EU field isolates and EU vaccine strain. A total of 80% of the samples of the basic package were analysed correctly, the analysis of the differentiation package I revealed 61.82% correctly tested samples and the two laboratories that analysed the differentiation package II showed only one correct result. The ring test showed that the majority of incorrect diagnoses were false-negative results.

With three clones of Spironucleus muris (S. muris)--established from a mouse, hamster, and rat--homologous and heterologous host species were experimentally infected. Each host was susceptible to the clone originating from the homologous donor. In addition, both mice and hamsters were susceptible to the reciprocal heterologous clones. In contrast, infections of the rat with both heterologous clones were very poor, i.e. quantitatively low and ephemeral. It was not possible to infect hamsters and mice, not even athymic, with S. muris from the rat. This suggests a strain heterogeneity within the genus S. muris. In general, the genetic background of the host influenced the infection, the sex of the host did not.

Summary Five groups of weaner pigs were intranasally inoculated with constant doses of bovine viral diarrhoea virus (BVDV) strain OSLOSS/2482. Four weeks post primary inoculation (p. p. i.) the animals were intranasally challenged with decreasing doses of hog cholera virus (HCV) strain Alfort/ 187. Clinical signs were not observed apart from a short febrile period (2 days, > 40 °C) in one animal. Another animal died intercurrently without showing any pathological signs. Virus isolation from leucocyte samples taken regularly during one week post challenge detected HC viraemia in most animals that had received HCV doses > 100 TCID50 per animal. Using monoclonal antibody (mab) analysis all isolates obtained were proven to be HCV. Serological investigations using the virus neutralization test (VNT) yielded HC neutralizing antibodies in all groups with higher titres in those animals having received HCV doses > 100 TCID50. However, HCV specific neutralizing antibodies never exceeded the BVDV antibody titre. A complex trapping blocking (CTB) ELISA applying a HCV specific mab detected HCV specific antibodies in animals that had gone through HC viraemia while discriminating BVDV specific antibodies.

Summary: Objective: Three experiments (EXP) were conducted to investigate if air contaminated with PRRS virus (Ingelvac PRRS MLV vaccine containing the North American strain) can be sucked into ultrasound machines and then expelled back into an infected (EXP-1) or a clean environment (EXP-3) through the action of ventilation fans, and if covering the machines prevents exhaust expulsion of the virus (EXP-2). Materials and methods: The experimental apparatus basically comprised of a plastic chamber, an ultrasound unit HS 1201, a device that allowed for virus aerosolization and a pipe system that allowed the air to return into the chamber (EXP-1) or to be expelled into the atmosphere (EXP-3), or was blocked by using a rubber membrane (EXP-2). In EXP-1, different virus concentrations were tested (i. e. 104, 105 and 106 TCID50, each concentration in three replicates and two runs). In EXP-2, the highest concentration, i. e. 106 TCID50 was used (three replicates and two runs). EXP-3 immediately followed EXP-2 without introduction of new virus (two runs). Virus exhaust expulsion was monitored by swabbing the pipe system with the swabs being subjected to RT-nPCR and culture. Results: In EXP-1, 106 TCID50 PRRSV, but none of the other concentrations, gave constantly virus-positive results by RT-nPCR. In EXP-2, covering completely prevented virus exhaust expulsion. In EXP-3, two out of eight swabs were positive by RT-nPCR. Cell culture of positive swabs was negative. Conclusion: The study suggests exhaust expulsion of PRRSV through ultrasound machines equipped with a ventilator fan into an infected and a clean environment, but failed to demonstrate infectivity of the expelled virus. Preventing exhaust air expulsion by complete covering prevents the expulsion of the virus.