Publications

The aim of this study was to assess the seroprevalence, viremia, genotype distribution, and demographic history of hepatitis C virus (HCV) in the Republic of the Congo. Testing was carried out on sera samples collected in 2005 from 807 Bantus belonging to the Kongo, Teke, and Ngala subgroups and 80 Pygmies. Positive HCV serology was found in 50 (5.6%) individuals including 31 (60%) who were viremic. Seroprevalence increased with age with a cutoff at 50 years: 2.8% 50. Twenty-one strains belonged to four described subtypes, that is, 4c in eight cases, 4h in two, 4k in three, and 4r in eight. Ten strains could not be assigned to any known subtype and may represent six new variants, that is, subtype 4 in five cases and subtype 2 in one. Evolutionary analysis of subtype 4c and 4r sequences indicated a period of enhanced transmission in the mid-twentieth century probably due to iatrogenic causes. This study underlines the high genetic diversity of strains in the Republic of the Congo with nine subtypes 4 and one subtype 2.

Recently, a new member of the Bluetongue virus (BTV) serogroup named Toggenburg Orbivirus (TOV) in goats from Switzerland has been described. The epidemiology and host range of TOV are currently unknown. Since TOV causes cross-reactions in laboratory tests used for BTV diagnosis, this study was carried out in order to determine the spatial and temporal spread of TOV. Therefore, serum samples from a national survey in goats, collected during winter and spring 2008 in Switzerland, were serologically examined. Additionally, cattle and sheep from holdings with seropositive goats were tested for the presence of viral RNA and antibodies against BTV and TOV. All goat samples analysed within routine diagnostics at the Institute of Virology and Immunoprophylaxis from 2008 to 2009 were also tested for the presence of TOV. Finally, goat sera collected 1998 in the Canton of Ticino (TI) were analysed. Although the TOV index cases had been identified in flocks north of the Alps, no additional TOV-positive herds were found by serological testing in this region. In contrast, south of the Alps, i.e. in the Canton of Ticino (TI), an apparent seroprevalence of 49% in goats was found at animal and 60% at herd level. In the eastern and western part of the Swiss Alps 15.2% and 10% of tested goats were serologically positive, respectively. A within-herd prevalence of up to 100% was found in some of the positive flocks. The positive flocks in TI were mainly found in three of the five districts, but seropositive animals were identified in each district. Certain selected seropositive flocks were investigated virologically. By RT-qPCR and genome sequencing, the presence of TOV could be confirmed in all investigated seropositive flocks. By testing the goats within routine diagnostics. TOV genome was detected in one goat showing BT-like clinical symptoms from the central Alps and in three healthy animals imported from Germany. Although 3.8% of the sheep from flocks with TOV-positive goats or in contact with these animals showed a positive antibody reaction, TOV-specific RNA was not found in any of the tested sheep and also not in cattle from flocks with TOV-positive goats.

Porcine circovirus type 2 (PCV2) is the essential etiological agent of postweaning multisystemic wasting syndrome (PMWS), a worldwide distributed pig disease. The involvement of the immune system in the pathogenesis of PMWS is considered crucial. Previous studies have shown a cytokine profile suggesting T immunosuppression and indicating that interleukin 10 (IL-10) may play an important role during PCV2 infection. Nine 11- to 12-week-old conventional pigs were obtained from commercial farms located in North-Eastern Spain with historical records of PMWS. Spleen from four healthy and five PMWS-affected animals were collected at the necropsy. Viral load was determined in serum by means of standard PCR and real-time quantitative PCR. Phenotype and distribution of different immune cells involved in IL-10 secretion in the spleen of studied pigs were analysed using immunofluorescent assays. The CD163(+), CD4(+), and CD8(+) cell subpopulations produced IL-10 in the spleen and IL-10(+) cell numbers were higher in PMWS animals compared with their healthy counterparts. Furthermore. IL-10 producing cells were not infected by PCV2 and were mainly localized in the periarteriolar lymphoid sheaths. This is the first immunophenotyping study on IL-10 producing cells in cases of PMWS, further extending the studies on the role of IL-10 in disease pathogenesis.

Enterohaemorrhagic Escherichia coli (EHEC) comprise a group of animal and zoonotic pathogens of worldwide importance. Our previous research established that intestinal colonization of calves by EHEC serotypes O5?:?H– and O111?:?H– requires EHEC factor for adherence (Efa-1), also known as lymphostatin (LifA). Towards an understanding of the mode of action of Efa-1/LifA, chromosomal in-frame deletions of predicted glycosyltransferase (DXD) and cysteine protease (CHD) motifs were created in a ?stx1 derivative of EHEC O26?:?H–. The magnitude and duration of faecal excretion of EHEC O26?:?H– were significantly reduced by null mutation of efa-1/lifA, but were not impaired by ?DXD or ?CHD mutations, in contrast to observations made with truncated Efa-1/LifA mutants of Citrobacter rodentium in mice. Although C. rodentium Efa-1/LifA influences the induction of colonic hyperplasia in mice, EHEC O26?:?H– Efa-1/LifA was not required for fluid accumulation or neutrophil recruitment in bovine ileal loops. In contrast to observations with EHEC O5?:?H– or O111?:?H– mutants, inactivation of efa-1/lifA in EHEC O26?:?H– did not significantly affect adherence or secretion of type III secreted proteins that play pivotal roles in calf colonization. Lymphostatin activity could not be reliably demonstrated in lysates of EHEC O26?:?H–; however, deletion of the glycosyltransferase and cysteine protease motifs in Efa-1/LifA from enteropathogenic E. coli O127?:?H6 abolished lymphostatin activity. Our data uncouple the role of Efa-1/LifA in calf colonization from effects on type III secretion and reinforce the potential for pathotype- and serotype-specific phenotypes.