No abstract

Characteristics of trans-splicing in Schistosoma mansoni were examined to explore the significance and determinants of spliced leader (SL) addition in flatworms. Only a small subset of mRNAs acquire the SL. Analysis of 30 trans-spliced mRNAs and four genes revealed no discernable patterns or common characteristics in the genes, mRNAs, or their encoded proteins that might explain the functional significance of SL addition. While the mRNA encoding the glycolytic enzyme enolase is trans-spliced, mRNAs encoding four other glycolytic enzymes are not, indicating trans-splicing is not prevalent throughout this metabolic pathway. Although the 3 end of flatworm SLs contribute an AUG to mRNAs, the SL AUG does not typically serve to provide a methionine for translation initiation of reading frames in recipient mRNAs. SL RNA expression exhibits no apparent sex, tissue, or cell specificity. Trans-spliced genes undergo both cis-and trans-splicing, and the sequence contexts for these respective acceptor sites are very similar. These results suggest trans-splicing in flatworms is most likely associated either with some property conferred on recipient mRNAs by SL addition or related to some characteristic of the primary transcripts or transcription of trans-spliced genes.Trans-splicing is an RNA processing event that accurately joins sequences derived from independently transcribed RNAs. In one form of trans-splicing, a leader sequence (the spliced leader, SL) 1 is donated from the 5Ј end of a small, non-polyadenylated RNA (the spliced leader RNA, SL RNA) to pre-mRNAs to form the 5Ј-terminal exon of mature mRNAs (for recent reviews see Refs. 1-6). This form of RNA maturation was first described in trypanosomes (7,8) and subsequently in other kinetoplastida and the flagellated protozoan Euglena (9). The identification of trans-splicing in two divergent invertebrate phyla, first in nematodes (10) and then in flatworms (11), suggests that this particular form of RNA processing may be an important form of gene expression common in early metazoa.The general distribution of trans-splicing and its origin in metazoa is currently not known. Furthermore, both the origin of early metazoan groups and the phylogenetic relationships between flatworms, nematodes, and other early invertebrates have been difficult to delineate (12, 13). Trans-splicing may have arisen independently in several invertebrate lineages (6) and, if true, the characteristics and functional significance of spliced leader addition might also be different in diverse metazoan groups. Trans-splicing is of particular interest in flatworms (Phylum Platyhelminthes) as these metazoa may represent the earliest bilateral animals, and one possible evolutionary tree places a flatworm-like ancestor as the progenitor of a number of other early invertebrate groups (12, 13). We have recently shown that trans-splicing is present in diverse trematode flatworms and in a predominantly free-living group generally considered to represent primitive flatworms (14). 2 This suggests that spliced ...

Chlamydiosis is a zoonotic disease in birds caused by Chlamydophila psittaci, an obligate intracellular bacterium. There are seven known avian outer-membrane protein A genotypes, A-F and E/B. The importance of genotyping lies in the fact that certain genotypes tend to be associated with certain hosts and a difference in virulence. Genotype B is the most prevalent in pigeons, but the more virulent genotypes A and D have also been discovered. The current study assessed the prevalence of C. psittaci in 32 Belgian homing-pigeon facilities and in 61 feral pigeons captured in the city of Ghent, Belgium. Additionally, zoonotic transmission of C. psittaci was investigated in the homing-pigeon facilities. Homing pigeons were often infected, as at least one of the lofts was positive in 13 of the 32 (40.6 %) pigeon breeding facilities. Genotypes B, C and D were detected. Zoonotic transmission was discovered in 4 of the 32 (12.5 %) pigeon fanciers, revealing genotype D in two of them, whilst genotyping was unsuccessful for the other two human pharyngeal swabs. This study clearly demonstrates the possible risk of C. psittaci zoonotic transmission from homing pigeons. Pigeon fanciers often (37.5 %) used antibiotics for prevention of respiratory disease. Because of the risk of developing drug-resistant strains, regular use of antimicrobial drugs must be avoided. This study is believed to be the first to detect C. psittaci in Belgian feral pigeons. The prevalence rate in the city of Ghent was extremely low, which is beneficial for public health. INTRODUCTIONChlamydiosis is a zoonotic disease in birds caused by Chlamydophila psittaci, an obligate intracellular bacterium. Symptoms include abnormal respiratory signs, nasal discharge, diarrhoea, polyuria and dullness (Vanrompay et al., 1995a). Zoonotic transmission happens through direct contact or inhalation of infected aerosols. The clinical course in humans varies from asymptomatic to severe systemic disease with interstitial pneumonia. Symptoms frequently include high fever (up to 40.5 uC) accompanied by a relatively low pulse, chills, headache, myalgia, non-productive coughing and difficulty breathing ). The incubation period ranges from 5 to 14 days.Currently, there are seven C. psittaci outer-membrane protein A (ompA) genotypes designated A-F and E/B. The importance of genotyping lies in the fact that certain genotypes tend to be associated with certain hosts and differ in virulence. Genotypes A and D are more virulent than genotype B (Vanrompay et al., 1994(Vanrompay et al., , 1995b. Genotypes A-E and E/B have been found in pigeons (Geens et al., 2005;Laroucau et al., 2008; Sayada et al., 1995). However, in Belgium and neighbouring countries, only genotypes A, B and D have been discovered so far (Vanrompay et al., 1993(Vanrompay et al., , 1997, with genotype B being the most prevalent (Magnino et al., 2009). Recently, genotype B has been discovered in three human samples in The Netherlands and may be an underestimated source of disease (Heddema et al., 2006b).In 1940, C. p...

IntroductionIn order to investigate the role of roe deer in the maintenance and transmission of infectious animal and human diseases in Flanders, we conducted a serologic screening in 12 hunting areas.Materials and methodsRoe deer sera collected between 2008 and 2013 (n=190) were examined for antibodies against 13 infectious agents, using indirect enzyme-linked immunosorbent assay, virus neutralisation, immunofluorescence, or microagglutination test, depending on the agent.Results and discussionHigh numbers of seropositives were found for Anaplasma phagocytophilum (45.8%), Toxoplasma gondii (43.2%) and Schmallenberg virus (27.9%), the latter with a distinct temporal distribution pattern following the outbreak in domestic ruminants. Lower antibody prevalence was found for Chlamydia abortus (6.7%), tick-borne encephalitis virus (5.1%), Neospora caninum (4.8%), and Mycobacterium avium subsp paratuberculosis (4.1%). The lowest prevalences were found for Leptospira (1.7%), bovine viral diarrhoea virus 1 (1.3%), and Coxiella burnetii (1.2%). No antibodies were found against Brucella sp., bovine herpesvirus 1, and bluetongue virus. A significant difference in seroprevalence between ages (higher in adults >1 year) was found for N. caninum. Four doubtful reacting sera accounted for a significant difference in seroprevalence between sexes for C. abortus (higher in females).ConclusionsDespite the more intensive landscape use in Flanders, the results are consistent with other European studies. Apart from maintaining C. abortus and MAP, roe deer do not seem to play an important role in the epidemiology of the examined zoonotic and domestic animal pathogens. Nevertheless, their meaning as sentinels should not be neglected in the absence of other wild cervid species.