Phylodynamics and Dispersal of HRSV Entails Its Permanence in the General Population in between Yearly Outbreaks in Children

Background: Human respiratory syncytial virus (HRSV) is one of the major etiologic agents of respiratory tract infections among children worldwide. Methodology/Principal Findings: Here through a comprehensive analysis of the two major HRSV groups A and B (n = 1983) which comprise of several genotypes, we present a complex pattern of population dynamics of HRSV over a time period of 50 years (1956-2006). Circulation pattern of HRSV revealed a series of expansions and fluctuations of co-circulating lineages with a predominance of HRSVA. Positively selected amino acid substitutions of the G glycoprotein occurred upon population growth of GB3 with a 60-nucleotide insertion (GB3 Insert), while other genotypes acquired substitutions upon both population growth and decrease, thus possibly reflecting a role for immune selected epitopes in linkage to the traced substitution sites that may have important relevance for vaccine design. Analysis evidenced the co-circulation and predominance of distinct HRSV genotypes in Brazil and suggested a year-round presence of the virus. In Brazil, GA2 and GA5 were the main culprits of HRSV outbreaks until recently, when the GB3 Insert became highly prevalent. Using Bayesian methods, we determined the dispersal patterns of genotypes through several inferred migratory routes. Conclusions/Significance: Genotypes spread across continents and between neighboring areas. Crucially, genotypes also remained at any given region for extended periods, independent of seasonal outbreaks possibly maintained by re-infecting the general population.

Evaluation of the probiotic potential and effect of encapsulation on survival for Lactobacillus plantarum ST16Pa isolated from papaya

Capability to produce antilisterial bacteriocins by lactic acid bacteria (LAB) can be explored by the food industry as a tool to increase the safety of foods. Furthermore, probiotic activity of bacteriogenic LAB brings extra advantages to these strains, as they can confer health benefits to the consumer. Beneficial effects depend on the ability of the probiotic strains to maintain viability in the food during shelf-life and to survive the natural defenses of the host and multiply in the gastrointestinal tract (GIT). This study evaluated the probiotic potential of a bacteriocinogenic Lactobacillus plantarum strain (Lb. plantarum ST16Pa) isolated from papaya fruit and studied the effect of encapsulation in alginate on survival in conditions simulating the human GIT. Good growth of Lb. plantarum ST16Pa was recorded in MRS broth with initial pH values between 5.0 and 9.0 and good capability to survive in pH 4.0, 11.0 and 13.0. Lb. plantarum ST16Pa grew well in the presence of oxbile at concentrations ranging from 0.2 to 3.0%. The level of auto-aggregation was 37%, and various degrees of co-aggregation were observed with different strains of Lb. plantarum, Enterococcus spp., Lb. sakei and Listeria, which are important features for probiotic activity. Growth was affected negatively by several medicaments used for human therapy, mainly anti-inflammatory drugs and antibiotics. Adhesion to Caco-2 cells was within the range reported for other probiotic strains, and PCR analysis indicated that the strain harbored the adhesion genes mapA, mub and EF-Tu. Encapsulation in 2, 3 and 4% alginate protected the cells from exposure to 1 or 2% oxbile added to MRS broth. Studies in a model simulating the transit through the GIT indicated that encapsulated cells were protected from the acidic conditions in the stomach but were less resistant when in conditions simulating the duodenum, jejunum, ileum and first section of the colon. To our knowledge, this is the first report on a bacteriocinogenic LAB isolated from papaya that presents application in food biopreservation and may be beneficial to the consumer health due to its potential probiotic characteristics.