Development of a rapid and sensitive latex agglutination-based method for detection of group A rotavirus.

Considering the background of morbidity and mortality caused by human rotavirus, detection methods that use rotavirus group antigen (VP6) in either enzyme immunoassay (EIA) or latex agglutination test (LAT) has been employed routinely in clinical diagnostic and epidemiological studies. In order to develop a rapid and sensitive rotavirus group A LAT, part of segment 6 corresponding to conserved N-terminal portion of the VP6 (1-245 aa) was cloned in Escherichia coli expression pGEX vector (glutathione S-transferase-GST gene fusion system) that has been modified previously containing a histidine tail at C-terminus. The immunological propriety of the recombinant VP6 having a total molecular weight of 52 kDa was evaluated by Western blot and by the ability of inducing anti-recombinant VP6 polyclonal antibodies in rabbit. The polyclonal serum produced was conjugated to a latex support to detect rotavirus in stool specimens. The percentage values for sensitivity and specificity of the rotavirus group A LAT were 98.5% and 100%, respectively.

Phylogeography of foot-and-mouth disease virus serotype O in Ecuador.

Foot-and-mouth disease virus (FMDV) is the causative agent of the most important disease of domestic cattle, foot-and-mouth disease. In Ecuador, FMDV is maintained at an endemic state, with sporadic outbreaks. To unravel the tempo and mode of FMDV spread within the country we conducted a Bayesian phylogeographic analysis using a continuous time Markov chain (CTMC) to model the diffusion of FMDV between Ecuadorian provinces. We implement this framework through Markov chain Monte Carlo available in the BEAST package to study 90 FMDV serotype O isolates from 17 provinces in the period 2002-2010. The Bayesian approach also allowed us to test hypotheses on the mechanisms of viral spread by incorporating environmental and epidemiological data in our prior distributions and perform Bayesian model selection. Our analyses suggest an intense flow of viral strains throughout the country that is possibly coupled to animal movements and ecological factors, since most of inferred viral spread routes were in Coast and Highland regions. Moreover, our results suggest that both short- and long-range spread occur within Ecuador. The province of Esmeraldas, in the border with Colombia and where most animal commerce is done, was found to be the most probable origin of the circulating strains, pointing to a transboundary behavior of FMDV in South America. These findings suggest that uncontrolled animal movements can create a favorable environment for FMDV maintenance and pose a serious threat to control programmes. Also, we show that phylogeographic modeling can be a powerful tool in unraveling the spatial dynamics of viruses and potentially in controlling the spread of these pathogens.