Molecular epidemiology of bluetongue virus in Portugal during 2004-2006 outbreak

Laboratório Nacional de Investigação Veterinária, Estrada de Benfica 701, 1549-011 Lisboa, Portugal.
Veterinary Microbiology (Impact Factor: 2.73). 10/2007; 124(1-2):25-34. DOI: 10.1016/j.vetmic.2007.04.014
Source: PubMed

ABSTRACT After 44 years of epidemiological silence, bluetongue virus (BTV) was reintroduced in Portugal in the autumn of 2004. The first clinical cases of bluetongue disease (BT) were notified in sheep farms located in the South of Portugal, close to the Spanish border. A total of six BTV, five of serotype 4 and one of serotype 2 were isolated from sheep and cattle during the 2004-2006 epizootics. The nucleotide sequence of gene segments L2, S7 and S10 of BTV-4 prototype strain (BTV4/22045/PT04) obtained from the initial outbreak and of BTV-2 (BTV2/26629/PT05) was fully determined and compared with those from other parts of the world. The phylogenetic analysis revealed that BTV4/22045/PT04 is related to other BTV-4 strains that circulate in the Mediterranean basin since 1998, showing the highest identity (99%) with BTV-4 isolates of 2003 from Sardinia and Corsica, whereas BTV2/26629/PT05 is almost indistinguishable from the Onderstepoort BTV-2 live-attenuated vaccine strain and its related field strain isolated in Italy. Since live-attenuated BTV-2 vaccine was never used in Portugal, the isolation of this strain may represent a natural circulation of the vaccine virus used in other countries in Mediterranean Europe.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Philippine Fault results from the oblique convergence between the Philippine Sea Plate and the Sunda Block/Eurasian Plate. The fault exhibits left-lateral slip and transects the Philippine archipelago from the northwest corner of Luzon to the southeast end of Mindanao for about 1200km. To better understand fault slip behavior along the Philippine Fault, eight GPS surveys were conducted from 1996 to 2008 in the Luzon region. We combine the 12-yr survey-mode GPS data in the Luzon region and continuous GPS data in Taiwan, along with additional 15 International GNSS Service sites in the Asia-Pacific region, and use the GAMIT/GLOBK software to calculate site coordinates. We then estimate the site velocity from position time series by linear regression. Our results show that the horizontal velocities with respect to the Sunda Block gradually decrease from north to south along the western Luzon at rates of 85–49mm/yr in the west–northwest direction. This feature also implies a southward decrease of convergence rate along the Manila Trench. Significant internal deformation is observed near the Philippine Fault. Using a two dimensional elastic dislocation model and GPS velocities, we invert for fault geometries and back-slip rates of the Philippine Fault. The results indicate that the back-slip rates on the Philippine Fault increase from north to south, with the rates of 22, 37 and 40mm/yr, respectively, on the northern, central, and southern segments. The inferred long-term fault slip rates of 24–40mm/yr are very close to back-slip rates on locked fault segments, suggesting the Philippine Fault is fully locked. The stress tensor inversions from earthquake focal mechanisms indicate a transpressional regime in the Luzon area. Directions of σ1 axes and maximum horizontal compressive axes are between 90° and 110°, consistent with major tectonic features in the Philippines. The high angle between σ1 axes and the Philippine Fault in central Luzon suggests a weak fault zone possibly associated with fluid pressure.
    Journal of Asian Earth Sciences 04/2012; 65. DOI:10.1016/j.jseaes.2010.12.007 · 2.83 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Recently, a contamination incident was described in which the challenge inoculum used in a bluetongue virus serotype 8 (BTV-8) vaccination trial was contaminated with a BTV-11 virus that was closely related to the Belgian BTV-11 virus from 2008. This study reports the first complete genome sequences of four BTV-11 viruses: the BTV-11 contaminant, BTV-11 reference strain, BTV-11 vaccine strain and a recently isolated BTV-11 field strain from Martinique. Full-genome analysis showed that these viruses belong to serotype 11/nucleotype A and cluster together with other western topotype bluetongue viruses. Detailed comparisons of the genomes further indicated that the contaminant was derived from the BTV-11 reference strain, as they were distinguished by a single synonymous nucleotide substitution. The previously reported partial sequence of genome segment 2 of the Belgian BTV-11 was found to be identical to that of the BTV-11 vaccine strain, indicating that it most likely was the BTV-11 vaccine strain. These findings also suggest that the BTV-11 contaminant and the Belgian BTV-11 are not the same viruses. Finally, comparison of the reference and vaccine strain did not allow determining the amino acid substitutions that contribute to the attenuated phenotype.
    Transboundary and Emerging Diseases 10/2013; DOI:10.1111/tbed.12178 · 2.10 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The increasing availability of novel molecular techniques has transformed the study of human health and disease epidemiology. However, uptake of such approaches has been more conservative in the field of wildlife disease epidemiology. We consider the reasons for this and discuss current and potential applications of molecular techniques in a variety of relevant areas within the field of wildlife disease research. These include conducting wildlife disease surveillance, identifying sources of pathogen emergence, uncovering host-pathogen dynamics and managing current outbreaks, including the development and monitoring of wildlife vaccines. We highlight key examples of applications of molecular epidemiological approaches to wildlife disease scenarios and draw parallels from human disease research to suggest potential future directions. The potential value of next generation sequencing technologies to the field of wildlife disease research is discussed, and initial applications are highlighted, balanced against consideration of the challenges involved. Using a wide range of examples drawn from research into human, livestock and wildlife diseases, we demonstrate the value of using molecular epidemiological approaches at all scales of wildlife disease research, from pathogen strains circulating at a global scale to intra-individual host-pathogen dynamics. The potential future contribution of these technologies to the field of wildlife disease epidemiology is substantial. In particular, they are likely to play an increasingly important role in helping us to address a principal challenge in the management of wildlife diseases which is how to tease apart the transmission dynamics of complex multi-host systems in order to develop effective and sustainable interventions.
    European Journal of Wildlife Research 12/2014; 61(1). DOI:10.1007/s10344-014-0882-4 · 1.21 Impact Factor

Full-text (2 Sources)

Available from
May 28, 2014