Understanding the virulence of Streptococcus suis: A veterinary,medical, and economic challenge

Streptococcus suis is a major swine pathogen worldwide and causes considerable economic losses in the swine industry. S. suis is also an emerging zoonotic agent, mainly in Asia. In pigs and humans, S. suis can cause septicemia, pneumonia, endocarditis, arthritis, and meningitis with irreversible sequelae. Identification and characterization of the virulence factors produced by S. suis are major advances in the understanding of the pathogenesis of S. suis infections and has therefore opened promising avenues for vaccine development against this pathogen. This literature review aimed to update the current knowledge of the virulence mechanisms of S. suis and of the vaccination strategies tested until now.     

Recombinaison génétique chez le poliovirus vaccinal : étude comparative chez les souches excrétées en cours de vaccination par le vaccin poliomyélitique oral et les souches circulantes

Aim of study

Recombination is one of the major mechanisms of evolution in poliovirus. In this work, recombination was assessed in children during vaccination with OPV and among circulating vaccine strains isolated in Tunisia during the last 15 years in order to identify a possible role of recombination in the response to the vaccine or the acquisition of an increased transmissibility.

Material and methods

This study included 250 poliovirus isolates: 137 vaccine isolates, excreted by children during primary vaccination with OPV and 113 isolates obtained from acute flaccid paralytic (AFP) cases and healthy contacts. Recombination was first assessed using a double PCR-RFLP, and sequencing.

Results

Nineteen per cent of recombinant strains were identified: 20% of strains excreted by vaccinees among 18% of circulating strains. The proportion of recombinant in isolates of serotype1 was very low in the two groups while the proportions of recombinants in serotypes 2 and 3 were different. In vaccinees, the frequency of recombinants in serotype3 decreased during the course of vaccination: 54% after the first dose, 32% after the second and 14% after the third dose.

Conclusion

These results suggest that recombination enhances the ability of serotype3 vaccine strains to induce an immune response. Apart from recent vaccination, it may contribute to a more effective transmissibility of vaccine strains among human population.     

Vaccination antigrippe A (H1N1) : analyse rétrospective 2009

The occurrence of the influenza A (H1N1) pandemic was the opportunity to set an appropriate vaccination campaign, effective and well tolerated within the shortest period of time. Thanks to a strong experience in the development of seasonal influenza vaccines and recent experimental knowledge on potential vaccines against H5N1 strain, pharmaceutical companies developed a new vaccine suited for the pandemic A H1N1 California July 2009 strain. This vaccine was produced with and without adjuvant, taking into account safety controls and evolution of scientific knowledge. Nevertheless, this campaign got a poor reception from the general and medical population due to the concomitant spread of the pandemics, an insufficient communication program, organization that was felt as unsuited, too complex and not well understood. Despite that, effectiveness and tolerance of the vaccination campaign have been observed with may be a positive effect on the epidemic.     

Pandémie grippale A/H1N1v,grossesse et vaccination

Seasonal flu is potentially more severe during pregnancy especially when it occurs in the last three months. Pregnant women were shown to be especially exposed to severe forms of the flu and death in the first weeks of the pandemic influenza A/H1N1v. For the first time in history, adequate vaccines were available in the early phase of the pandemic and recommended by WHO as a priority for pregnant women. In France, vaccination with the non-adjuvanted vaccine (Panenza^®) was recommended after three months of pregnancy. However, the pandemic vaccines were discredited by the mass media and the population even before they were available. This was due to several factors, and especially to the lack of information on the vaccine and its potential toxicity and, in case of pregnancy, potential risk of adverse fetal events, despite the fact that available data shows the seasonal flu vaccine is effective and well tolerated in pregnant women. This article aimed to provide decisional elements for influenza A/H1N1v vaccination in pregnant women.