Detection and Quantification of HspX Antigen in Sputum Samples Using Plasmonic Biosensing: Toward a Real Point-of-Care (POC) for Tuberculosis Diagnosis.

Advancements that occurred during the last years in the diagnosis of Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis infection, have prompted increased survival rates of patients. However, limitations related to the inefficiency of an early detection still remain; some techniques and laboratory methods do not have enough specificity and most instruments are expensive and require handling by trained staff. In order to contribute to a prompt and effective diagnosis of tuberculosis, we report the development of a portable, user-friendly, and low-cost biosensor device for its early detection. By using a label-free surface plasmon resonance (SPR) biosensor, we have established a direct immunoassay for the direct detection and quantification of the heat shock protein X (HspX) of Mtb, a well-established biomarker of this pathogen, directly in pretreated sputum samples. The method relies on highly specific monoclonal antibodies that are previously immobilized on the plasmonic sensor surface. This technology allows for the direct detection of the biomarker without amplification steps, showing a limit of detection (LOD) of 0.63 ng mL-1 and a limit of quantification (LOQ) of 2.12 ng mL-1. The direct analysis in pretreated sputum shows significant differences in the HspX concentration in patients with tuberculosis (with concentration levels in the order of 116-175 ng mL-1) compared with non-tuberculosis infected patients (values below the LOQ of the assay).

G and P genotypes of rotavirus circulating among children with diarrhea in the Colombian northern coast / Genotipos G y P de rotavirus encontrados en niños aquejados de diarrea en la costa norte de Colombia

A study on the prevalence of rotavirus G and P genotypes was carried out based on 253 stool specimens obtained from children living in the Colombia northern coast region who were less than 3-years-old and who suffered from acute diarrhea. A previous study had detected the presence of rotavirus A in 90 (36.5%) of the 246 samples tested by enzyme immunoassay (EIA), and these strains were investigated in the present study. Of these, 50 strains yielded an RNA electropherotype, most of which (80.0%) had long profiles and 20.0% of which had short profiles. Genotyping of 84 positive samples indicated that 67.9% of the strains could be typed. G1 (57.9%), was the most predominant VP7 genotype, followed by G3 (21.1%), G9 (15.8%) and G2 (5.3%). Among the VP4 genotypes, P[4] (49.1%) was the most prevalent, followed by P[6] 36.4% and P[8] (14.5%). Neither G4 nor G8 nor P[9] types were detected. The most common G-P combinations were G3 P[4] (8.8%) and G9 P[6] (7.0%), followed by G1 P[4] and G1 P[8] (5.3% each). All G1 P[8] strains showed long RNA profiles, whereas G3 P[4] and G9 P[6] displayed both long and short patterns. Mixed infections involved 21.0% of strains. There was a marked diversity among strains collected, and novel strains, including G9, as well as other atypical combinations of G and P genotypes, such as G9 P[6] and G3 P[4], were found (AU)

El artículo describe un estudio de la prevalencia de los genotipos G y P de rotavirus en 253 muestras fecales de niños menores de 3 años afectados de diarrea aguda que vivían en la costa norte de Colombia. Un estudio anterior reveló la presencia de rotavirus A en 90 (36.5%) de las 246muestras sometidas a inmuno ensayo y dichas muestras fueron las usadas en este estudio. En 50 de las 90 muestras usadas se obtuvo un electroferotipo, un 80.0% de perfil de RNA largo y un 20.0% de perfil de RNA corto. De 84muestras sometidas a genotipificación, se logró tipificar 67.9%. El genotipo G1(57.9%) fue predominante entre los asociados a VP7, seguido de G3(21.1%), G9 (15.8%) y G2 (5.3%). Entre los genotipos VP4, el P[4] (49.1%)fue el de mayor prevalencia, seguido de P[6] 36.4% y de P[8] (14.5%). No se detectaron los genotipos G4, G8 o P[9], y las combinaciones G-P más frecuentes fueron G3 P[4] ( 8.8%) y G9 P[6] (7.0%), seguidas de G1 P[4] y G1P[8], con 5.3% cada una. Todas las cepas G1 P[8] tenían perfil de RNA largo, mientras que G3 P[4] y G9 P[6] los tenían tanto largos como cortos. Se detectaron infecciones mixtas en el 21.0% de las cepas. Se observó una marcada diversidad en las cepas recolectadas y se identificaron cepas nuevas, como G9, y también combinaciones atípicas, como G9 P[6] y G3P[4] (AU)