To address the initiation of virus infection in the respiratory tract, we established two culture systems for differentiated bovine airway epithelial cells (BAEC). Filter-grown BAEC differentiated under air-liquid interface (ALI) conditions to generate a pseudo-stratified mucociliary epithelium. Alternatively, precision-cut lung slices (PCLS) from the bovine airways were generated that retained the original composition and distribution of differentiated epithelial cells. With both systems, epithelial cells were readily infected by bovine parainfluenza virus 3 (BPIV3). Ciliated cells were the most prominent cell type affected by BPIV3. Surprisingly, differentiated BAEC were resistant to infection by bovine respiratory syncytial virus (BRSV), when the virus was applied at the same multiplicity of infection that was sufficient for infection by BPIV3. In the case of PCLS, infection by BRSV was observed in cells located in lower cell layers but not in epithelial cells facing the lumen of the airways. The identity of the infected cells could not be determined because of a lack of specific antibodies. Increasing the virus titer 30-fold resulted in infection of the ALI cultures of BAEC, whereas in PCLS the ciliated epithelium was still refractory to infection by BRSV. These results indicate that differentiated BAEC are readily infected by BPIV3 but rather resistant to infection by BRSV. Disease caused by BRSV may require that calves encounter environmental stimuli that render BAEC susceptible to infection.

To evaluate current prevalence rates of 24 viruses and of the bacterium Mycoplasma pulmonis, the authors retrospectively surveyed serological data obtained from laboratory mice and rats housed in more than 100 western European institutions. Serum samples were submitted to the authors' institution for testing between January 2007 and June 2008. The prevalence of an infection was defined as the percentage of tested samples that yielded positive results for a specific agent. In mice, the most commonly detected infectious agents were murine norovirus (prevalence of 31.8%), mouse hepatitis virus (5.5%), mouse rotavirus (1.7%) and parvoviruses (1.0%). In rats, parvoviruses (12.1%) and M. pulmonis (3.6%) were the most prevalent infectious agents. Most rodent parvovirus infections could be attributed to mouse parvovirus in mice and to rat minute virus or to Kilham rat virus in rats. These data suggest the importance of up-to-date animal health monitoring programs and should stimulate the scientific community to further improve the microbiological quality of laboratory rodents.

The intracellular transport of the surface glycoprotein E2 of bovine viral diarrhoea virus was analysed by expressing the cloned gene in the absence of other viral proteins. Immunofluorescence analysis and surface biotinylation indicated that E2 is located in an early compartment of the secretory pathway and not transported to the cell surface. In agreement with this result, E2 was found to contain only high-mannose oligosaccharide side-chains but no N-glycans of the complex type. To define the intracellular localization signal of the E2 protein, chimeric proteins were generated. E2 chimeras containing the MT (membrane anchor plus carboxy-terminal domain) of the G protein of vesicular stomatitis virus (VSV) or of the F protein of bovine respiratory syncytial virus (BRSV) were transported to the cell surface. On the other hand, VSV G protein containing the MT domain of E2 was detected only in the ER, indicating that this domain contains an ER localization signal. A chimeric E2 protein, in which not the membrane anchor but only the carboxy-terminal end was replaced by the corresponding domain of the BRSV F protein, was also localized in the ER. Therefore, it was concluded that the membrane anchor contains the ER localization signal of E2. Interestingly, the ER export signal within the VSV G protein cytoplasmic tail was found to overrule the ER localization signal in the E2 protein membrane anchor.

In this study, we investigated the prevalence of infectious microorganisms (viruses, bacteria, fungi and eukaryotic parasites) in mice from different pet shops in Germany; such animals may compromise the hygienic integrity of laboratory animal vivaria if private pet holders act as unintended vectors of infections carried by them. House mice sold as pets or feed specimens were purchased from different pet shops and tested for a comprehensive panel of unwanted microorganisms. We found a number of microorganisms in these pet shop mice, the most prevalent of which were Helicobacter species (92.9%), mouse parvovirus (89.3%), mouse hepatitis virus (82.7%), Pasteurella pneumotropica (71.4%) and Syphacia species (57.1%). Several microorganisms (e.g. mouse parvovirus, Theiler's murine encephalomyelitis virus, pneumonia virus of mice, Encephalitozoon cuniculi, Clostridium piliforme) had considerably higher prevalences than those reported in similar studies on wild mice from North America, Europe or Australia. Our study shows that direct contact with pet shop mice may constitute a risk for laboratory animal vivaria if hygienic precautions are not taken. However, even relatively simple precautions seem effective enough to hold the risk at bay.

This study analysed the transport behaviour of the glycoprotein E2 of Bovine viral diarrhea virus (BVDV) expressed from recombinant vesicular stomatitis virus (rVSV). E2 protein was found to be retained at an intracellular compartment. A chimeric protein containing the membrane anchor and cytoplasmic tail of the VSV G protein, E2-G(MT), was transported to the cell surface. Only the latter protein was incorporated into rVSV particles in significant amounts. A soluble form of E2 lacking the membrane anchor, E2(MTdel), appeared to be affected in conformational stability. In contrast to both membrane-anchored forms of E2, expression of the soluble form was detectable only by immunofluorescence microscopy but not by Western blotting. These results are in agreement with reports of intracellular retention of the E2 protein due to a retention signal in the membrane anchor. However, in another analysis of E2 expressed from rVSV, E2 protein was reported to be transported to the cell surface and incorporated into VSV particles [Grigera,