Alexandre Almeida

Detection and discrimination of common bovine mastitis-causing streptococci.

Detection and typing of bovine mastitis pathogens are currently limited by time-consuming and culture-based techniques. In this work, a novel genus-specific DNA marker for Streptococcus and species-specific DNA markers for the prevalent mastitis pathogens Streptococcus agalactiae and Streptococcus uberis were designed and assessed. In order to enable further discrimination of these mastitis-causing streptococci, metabolic and pathogenicity-related genes were used to infer additional functional markers. A total of 12 DNA markers were validated with a set of 50 reference strains and isolates, representative of the Streptococcus genus, of closely related species and of microorganisms with matching habitats. The experimental validation, using dot blot hybridization under high stringency conditions, confirmed the specificity of the selected markers. The broad-spectrum taxonomic marker (ST1) was specific to the Streptococcus genus and the markers selected for S. agalactiae (A1 and A2) and S. uberis (U1 and U2) were shown to be species-specific. The functional markers revealed strain-specific patterns of S. agalactiae and S. uberis. Markers derived from the fructose operon (FO1 and FO3) were specific to bovine isolates of S. agalactiae, and the nisin operon markers (NU1 and NU3) were able to discriminate isolates belonging to S. agalactiae and S. uberis. The virulence-associated markers (V1, V2 and V3) allowed the detection of S. uberis and of closely related species. This work suggests that the combined use of these novel taxa-specific markers coupled with discriminatory functional markers presents a promising approach for the rapid and cost-effective detection and discrimination of common bovine mastitis-causing pathogens, which will contribute to an improved treatment and control of this disease.

Persistence of a dominant bovine lineage of group B Streptococcus reveals genomic signatures of host adaptation.

Group B Streptococcus (GBS) is a host-generalist species, most notably causing disease in humans and cattle. However, the differential adaptation of GBS to its two main hosts, and the risk of animal to human infection remain poorly understood. Despite improvements in control measures across Europe, GBS is still one of the main causative agents of bovine mastitis in Portugal. Here, by whole-genome analysis of 150 bovine GBS isolates we discovered that a single CC61 clone is spreading throughout Portuguese herds since at least the early 1990s, having virtually replaced the previous GBS population. Mutations within an iron/manganese transporter were independently acquired by all of the CC61 isolates, underlining a key adaptive strategy to persist in the bovine host. Lateral transfer of bacteriocin production and antibiotic resistance genes also underscored the contribution of the microbial ecology and genetic pool within the bovine udder environment to the success of this clone. Compared to strains of human origin, GBS evolves twice as fast in bovines and undergoes recurrent pseudogenizations of human-adapted traits. Our work provides new insights into the potentially irreversible adaptation of GBS to the bovine environment.

From Concept to Policy: Building Regional Innovation Systems in Follower Regions

In the spirit of “The Lisbon strategy”, public policies are redirecting support from investment-driven policies to knowledge building as the main driver for competitiveness and innovation. This re-orientation poses different challenges to regions, and the regional innovation system (RIS) concept may be the central element, simultaneously goal and toolbox, for devising innovation-promotion policies. The RIS framework stresses the need to combine a systemic and inclusive view of innovation along with territorially embedded specificities. In this paper, we explore how to operationalize the concept of RIS in terms of innovation policy, arguing against a “one-size-fits-all” approach. Concentrating our analysis on follower regions, we bridge the concept of RIS with the structural deficiencies and challenges posing to this kind of regions, for which innovation policy should seek an adequate combination between science-push and demand-pull perspectives. We also address the importance of taking advantage of the catching-up status, building upon the research and development cost advantages and clustering around external initiatives as well as the correction of important constraints to the construction of a RIS.

SBTC versus trade: testing skill-premia evidence across 25 OECD countries

The recent widening of intra-country wage inequality in favour of high-skilled labour has been attributed by some authors to Skill-Biased Technological Change (SBTC) and by others to International Trade (IT) liberalization. As few empirical studies have tried to assess both explanations across a comprehensive sample of countries, we analyse the impact of both explanations within a unified framework and across 25 Organisation for Economic Co-operation and Development countries. Results suggest that the SBTC (IT) explanation dominates in developed (developing) countries and when intra-country wage inequality is measured by the wage ratio of college-to-lower (upper)-secondary graduates.

Parallel Evolution of Group B Streptococcus Hypervirulent Clonal Complex 17 Unveils New Pathoadaptive Mutations

The incidence of group B Streptococcus (GBS) neonatal disease continues to be a significant cause of concern worldwide. Strains belonging to clonal complex 17 (CC17) are the most frequently responsible for GBS infections in neonates, especially among late-onset disease cases. Therefore, we undertook the largest genomic study of GBS CC17 strains to date to decipher the genetic bases of their remarkable colonization and infection ability. We show that crucial functions involved in different steps of the colonization or infection process of GBS are distinctly mutated during the adaptation of CC17 to the human host. In particular, our results implicate the CovRS two-component regulator of virulence in the differentiation between carriage- and disease-associated isolates. Not only does this work raise important implications for the ongoing development of a vaccine against GBS but might also drive the discovery of key functions for GBS adaptation and pathogenesis that have been overlooked until now. ABSTRACT Group B Streptococcus (GBS) is a commensal of the gastrointestinal and genitourinary tracts, while a prevailing cause of neonatal disease worldwide. Of the various clonal complexes (CCs), CC17 is overrepresented in GBS-infected newborns for reasons that are still largely unknown. Here, we report a comprehensive genomic analysis of 626 CC17 isolates collected worldwide, identifying the genetic traits behind their successful adaptation to humans and the underlying differences between carriage and clinical strains. Comparative analysis with 923 GBS genomes belonging to CC1, CC19, and CC23 revealed that the evolution of CC17 is distinct from that of other human-adapted lineages and recurrently targets functions related to nucleotide and amino acid metabolism, cell adhesion, regulation, and immune evasion. We show that the most distinctive features of disease-specific CC17 isolates were frequent mutations in the virulence-associated CovS and Stk1 kinases, underscoring the crucial role of the entire CovRS regulatory pathway in modulating the pathogenicity of GBS. Importantly, parallel and convergent evolution of major components of the bacterial cell envelope, such as the capsule biosynthesis operon, the pilus, and Rib, reflects adaptation to host immune pressures and should be taken into account in the ongoing development of a GBS vaccine. The presence of recurrent targets of evolution not previously implicated in virulence also opens the way for uncovering new functions involved in host colonization and GBS pathogenesis. IMPORTANCE The incidence of group B Streptococcus (GBS) neonatal disease continues to be a significant cause of concern worldwide. Strains belonging to clonal complex 17 (CC17) are the most frequently responsible for GBS infections in neonates, especially among late-onset disease cases. Therefore, we undertook the largest genomic study of GBS CC17 strains to date to decipher the genetic bases of their remarkable colonization and infection ability. We show that crucial functions involved in different steps of the colonization or infection process of GBS are distinctly mutated during the adaptation of CC17 to the human host. In particular, our results implicate the CovRS two-component regulator of virulence in the differentiation between carriage- and disease-associated isolates. Not only does this work raise important implications for the ongoing development of a vaccine against GBS but might also drive the discovery of key functions for GBS adaptation and pathogenesis that have been overlooked until now. Author Video: An author video summary of this article is available.

Wage inequality determinants in European Union countries

The explanation of the recent increase in intra-country wage inequality in favour of high-skilled labour has been dominated by two explanations: skill-biased technological change (SBTC) and international trade (IT) liberalization. Since few empirical studies have tried to assess both explanations across a comprehensive sample of countries, we analyse the impact of both and add some new variables within a unified framework and across 18 European Union countries. Results show that the SBTC, the immigration and education present an impact positive on wage inequality measured by the wage ratio of college to secondary graduates.

Trade, SBTC and Skill Premia – A Cross-Country and Cross-Gender Analysis

A recent study by Autor et al. (2008) has pointed out that the skill premia has risen in the US since the 60s. Several other authors have highlighted these trends across different OECD countries (e.g., Katz and Murphy, 1992; Machin, 1996; Goldin and Katz, 1999; Chay and Lee, 2000, Conte and Vivarelli, 2007). A common consensus points to the on-going growth of the demand for high-skilled workers, of which the Skill-Biased Technical Change (SBTC) and International Trade (IT) are the often cited sources.