Outbreaks of severe respiratory disease caused by bovine respiratory syncytial virus (BRSV) were recorded in dairy herds throughout Sweden in 1988 and subsequently. The virus was demonstrated in nasopharyngeal swab material from animals in the acute stage of the disease by culture, the polymerase chain reaction (PCR) and by immunofluorescence. Serological data from the herds investigated showed that the cows had seroconverted to BRSV rather than to bovine coronavirus, bovine viral diarrhoea virus or parainfluenza-3 virus. It was predominantly dairy herds in isolated areas that contracted a severe primary BRSV infection, often after the purchase of new animals. A nationwide survey for BRSV antibodies in bulk milk samples showed the highest prevalence, of 84 to 89 per cent, in the southernmost regions of Sweden and the lowest prevalence, of 41 to 51 per cent, in the north of the country. The prevalence of BRSV was highest in areas with the highest populations of cattle.

Two nested PCR assays were developed for the detection of bovine respiratory syncytial virus (BRSV). Primers were selected from the gene encoding the F fusion protein (PCR-F) and the gene encoding the G attachment protein (PCR-G). Biotinylated oligonucleotide probes, termed F and G, were selected for the hybridization of the respective PCR products. The sensitivities of the PCR-F and PCR-G assays were similar, both detecting 0.1 tissue culture infective dose of the virus. The PCR-F assay amplified all bovine strains and one human strain (RS32) tested. No cross-reactions were observed with nine heterologous respiratory viruses. PCR-F products of bovine and human RSV strains were discriminated by using endonuclease restriction enzyme Scal, which specifically cleaved products of BRSV. Oligonucleotide probe F was also specific for products of BRSV. The PCR-G assay detected all bovine strains and none of the human strains tested. A faint electrophoretic band was also observed with products of Sendai virus. However, probe G did not hybridize with this product, only with products of BRSV. Nasal swabs collected from cattle with no symptoms and cattle in the acute stage of respiratory disease were analyzed for BRSV by the immunofluorescence (IF) method and by the PCR-F and PCR-G assays. The virus was detected by the PCR assays in 31 of 35 (890%) samples tested. Only 23 samples (66%) were positive by the IF method, and these samples were also positive by both the PCR-F and PCR-G assays. The 31 samples detected as positive by PCR originated from cattle presenting clinical signs of acute respiratory disease; the four PCR-negative samples originated from clinically asymptomatic neighboring cattle. All sampled animals subsequently seroconverted and became reactive to BRSV. Thus, the detection of BRSV by PCR correlated with clinical observations and was considerably more sensitive (66 versus 89%) than IF. These results indicate that both nested PCR assays provide rapid and sensitive means for the detection of BRSV infection in cattle. Considering its higher specificity, the PCR-F assay can be recommended as the method of choice in the analysis of clinical specimens of BRSV.

Abstract. Within the framework of the active surveillance for transmissible spongiform encephalopathies in sheep in Sweden, 4 cases of the atypical form of scrapie, Nor98, were identified during 2003. Nor98 is a recently recognized and poorly understood variant of scrapie, first described in Norway. The cases were positive by the rapid test (enzyme-linked immunosorbent assay). Immunohistochemical staining showed diffuse thingranular staining of the cerebellar cortex. Western immunoblotting analysis of specimens of brain stem and cerebellum showed a light band of approximately 12 kDa. Typical scrapie was ruled out based on the confirmatory testing. The affected ewes were from 4 different flocks. They were between 7 and 9 years old. Two were of the ARQ/ARQ genotype, 1 ARR/ARQ, and 1 ARR/AHQ. Two ewes had shown ataxia, and the other 2 had no clinical signs. Whole-flock slaughter was applied, and testing of the flock mates did not reveal additional cases. Nor98 differs from typical scrapie in its epidemiology, frequency of genotypes of sheep affected, clinical signs, microscopic lesions, distribution of scrapie prion protein in the brain, and characteristics of the immunostaining and immunoblotting profiles.

After 27 years with no detected cases, an outbreak of anthrax occurred in a beef cattle herd in the south of Sweden. The outbreak was unusual as it occurred in winter, in animals not exposed to meat-and-bone meal, in a non-endemic country.The affected herd consisted of 90 animals, including calves and young stock. The animals were kept in a barn on deep straw bedding and fed only roughage. Seven animals died during 10 days, with no typical previous clinical signs except fever. The carcasses were reportedly normal in appearance, particularly as regards rigor mortis, bleeding and coagulation of the blood. Subsequently, three more animals died and anthrax was suspected at necropsy and confirmed by culture and PCR on blood samples.The isolated strain was susceptible to tetracycline, ciprofloxacin and ampicillin. Subtyping by MLVA showed the strain to cluster with isolates in the A lineage of Bacillus anthracis.Environmental samples from the holding were all negative except for two soil samples taken from a spot where infected carcasses had been kept until they were picked up for transport.The most likely source of the infection was concluded to be contaminated roughage, although this could not be substantiated by laboratory analysis. The suspected feed was mixed with soil and dust and originated from fields where flooding occurred the previous year, followed by a dry summer with a very low water level in the river allowing for the harvesting on soil usually not exposed. In the early 1900s, animal carcasses are said to have been dumped in this river during anthrax outbreaks and it is most likely that some anthrax spores could remain in the area.The case indicates that untypical cases in non-endemic areas may be missed to a larger extent than previously thought. Field tests allowing a preliminary risk assessment of animal carcasses would be helpful for increased sensitivity of detection and prevention of further exposure to the causative agent.

SUMMARYISCOM is an efficient mucosal delivery system for RSV envelope proteins as measured by antibody responses in respiratory tract secretions and in sera of mice following two intranasal (i.n.) administrations. Intranasally administered RSV ISCOMs induced high levels of IgA antibodies both in the upper respiratory tract and in the lungs. In the lungs, a prominent and long-lasting IgA response was recorded, which still persisted 22 weeks after the second i.n. immunization when the experiment ended. Subcutaneous (s.c.) immunization only induced low IgA titres in the upper respiratory tract and no measurable response to RSV was found in the lungs. Differences were also noticed in serum between the i.n. and s.c. modes of immunization. ISCOMs given intranasally induced earlier, higher and longer lasting IgM and IgG1 serum anti-RSV antibody responses than those induced by the s.c. mode of administration. A low serum IgE response was only detectable at 2 weeks after i.n. immunization with ISCOMs and after s.c. immunization with an inactivated virus, but no IgE response was detectable after s.c. injection of ISCOMs. The serum IgA response was more pronounced following s.c. injection of inactivated virus than after i.n. application of ISCOMs, and a clear-cut booster effect was obtained with a second immunization. Virtually no serum IgA response was detected after the s.c. administration of ISCOMs. In conclusion, the high immune responses induced by RSV ISCOMs in the respiratory tract and serum after i.n. administration indicate prominent mucosal delivery and adjuvant properties of the ISCOMs, warranting further studies.