Identification and characterization of two variants of the Hfq-sRNA-chaperone in the fish pathogen Piscirickettsia salmonis.

Small RNA and chaperone proteins form synergistic duos that play pivotal roles in controlling gene expression in bacteria. This is the case for Hfq, a highly pleiotropic pretranslational modulator of general protein expression, which responds to harsh environmental conditions and influences fitness and virulence in a wide range of pathogenic Enterobacteria. Given this relevancy, we evaluated the presence and potential role of Hfq in the fish pathogen Piscirickettsia salmonis, a Gram-negative bacterium that threatens the sustainability of Chilean salmon production. Using bioinformatics tools were identified and characterized two variants of Hfq, which share the consensus RNA-binding domains and the active sites described functional Hfq other bacteria. Additionally, we demonstrated that hfq-1 and hfq-2 were transcriptionally active when growing in cell-free media and in infected susceptible fish cell line. Expression of both genes differed under different growth conditions and under stress, suggesting that their roles might be independent and different, depending on the bacterial physiological status. In conclusion, we demonstrate the existence of two different and functional ORF coding for the hfq marker in marine bacteria and a preliminary analysis indicating that these two novel proteins might have relevant roles in the biology and pathogenic potential of P. salmonis.

Comparative assessment of a DNA and protein Leishmania donovani gamma glutamyl cysteine synthetase vaccine to cross-protect against murine cutaneous leishmaniasis caused by L. major or L. mexicana infection.

Leishmaniasis is a major health problem and it is estimated that 12 million people are currently infected. A vaccine which could cross-protect people against different Leishmania spp. would facilitate control of this disease as more than one species of Leishmania may be present. In this study the ability of a DNA vaccine, using the full gene sequence for L. donovani gamma glutamyl cysteine synthetase (γGCS) incorporated in the pVAX vector (pVAXγGCS), and a protein vaccine, using the corresponding recombinant L. donovani γGCS protein (LdγGCS), to protect against L. major or L. mexicana infection was evaluated. DNA vaccination gave transient protection against L. major and no protection against L. mexicana despite significantly enhancing specific antibody titres in vaccinated infected mice compared to infected controls. Vaccination with the LdγGCS protected against both species but only if the protein was incorporated into non-ionic surfactant vesicles for L. mexicana. The results of this study indicate that a L. donovani γGCS vaccine could be used to vaccinate against more than one Leishmania species but only if the recombinant protein is used.

Pathological findings in South American fur seal pups (Arctocephalus australis gracilis) found dead at Guafo Island, Chile.

During four breeding seasons (2004-2008), 78 necropsy examinations were performed on South American fur seal pups (Arctocephalus australis gracilis) found dead on Guafo Island, southern Chile (43°36'S, 74°43'W). Tissue samples from 65 pups were examined microscopically. The primary causes of death were enteritis with microscopical lesions of bacteraemia (28.2%), starvation (23.1%), drowning (21.8%), trauma (19.2%) and stillbirth (2.6%). Those pups with enteritis and microscopical lesions of bacteraemia had haemorrhagic enteritis (100%), interstitial pneumonia (86%), periportal hepatitis (73%) and vasculitis (18%). The pups that died from starvation had atrophy of hepatocytes (61%) and cholestasis (61%). The pups that drowned had bronchoalveolar oedema (65%) and foreign bodies in the airways (65%). In animals that died from trauma, the main lesions were skull fractures (67%). This range of pathological findings is within what would be expected in a healthy otariid breeding colony.

Utilidad de la transcripción reversa-reacción en cadena de la polimerasa (RT-PCR) para la vigilancia proactiva y el diagnóstico clínico del dengue / Utility of everse-reaction transcrptions in chain of polimerase (RT-PCR) to the proactive surveillance and clinical diagnoses of dengue

Un sistema de vigilancia proactiva efectivo para dengue requiere de técnicas de laboratorio rápidas y confiable que puedan detectar tempranamente la transmisión viral para predecir las epidemias con suficiente anticipación. En este sentido, la técnica de reverso transcripción-reacción en cadena de la polimerasa (RT-PCR) es una alternativa que ha sido utilizada exitosamente en sistema de vigilancia proactiva de centro y Sur América. En este estudio comparamos las cualidades del diagnóstico confirmatorio temprano del dengue de las técnicas RT-PCR, aislamiento viral en células C6/36 y serotipificación con anticuerpos con monoclonales antidengue (AIV), ensayo inmunoenzimático de captura de IgM anti-dengue (MAC-ELISA) y la inhibición de la hemaglutinación (IHA). Para el estudio utilizamos 1.019 sueros de pacientes atendidos por el sistema de vigilancia proactiva del estado Aragua, Venezuela. Los resultados desmotraron que la RT_PCR tuvo: a)mayores tasas de positividad que el AIV, el MAC-ELISA y la IHA, b)Alta sensibilidad (100 por ciento) y aceptable especificidad (73,5 por ciento) respecto al AIV y c)buena eficacia y rapidez en obtener resultados en los cuatros días iniciales de la enfermedad. Estas cualidades la convierte en una poderosa herramienta para la vigilancia proactiva del dengue(au)