Population-level seropositivity trend for SARS-Cov-2 in Rio Grande do Sul, Brazil

ABSTRACT OBJECTIVE To describe the evolution of seropositivity in the State of Rio Grande do Sul, Brazil, through 10 consecutive surveys conducted between April 2020 and April 2021. METHODS Nine cities covering all regions of the State were studied, 500 households in each city. One resident in each household was randomly selected for testing. In survey rounds 1-8 we used the rapid WONDFO SARS-CoV-2 Antibody Test (Wondfo Biotech Co., Guangzhou, China). In rounds 9-10, we used a direct ELISA test that identifies IgG to the viral S protein (S-UFRJ). In terms of social distancing, individuals were asked three questions, from which we generated an exposure score using principal components analysis. RESULTS Antibody prevalence in early April 2020 was 0.07%, increasing to 10.0% in February 2021, and to 18.2% in April 2021. In round 10, self-reported whites showed the lowest seroprevalence (17.3%), while indigenous individuals presented the highest (44.4%). Seropositivity increased by 40% when comparing the most with the least exposed. CONCLUSIONS The proportion of the population already infected by SARS-Cov-2 in the state is still far from any perspective of herd immunity and the infection affects population groups in very different levels.

Degradation of citronellol, citronellal and citronellyl acetate by Pseudomonas mendocina IBPse 105

The purpose of this work was to study the biodegradation of citronellol, citronellal and citronellyl acetate by a soil Pseudomonas mendocina strain (IBPse 105) isolated from a Cymbopogon windelandi field. This strain efficiently used citronellol, citronellal, citronellyl acetate and myrcene as sole source of carbon, but was not able to grow on other 15 monoterpenoids evaluated. Gas chromatography-mass spectrometry (GC-MS) analysis of metabolites accumulation during P. medocina IBPse 105 growth on citronellol showed that this strain uses the citronellol catabolic pathway described for other species of the genus. IBPse 105 degradation of citronellyl acetate initiates by its hydrolysis to citronellol. The mini-Tn5 insertion in mutant IBPse 105-303, impaired in citronellol degradation, but able to grow on citronellal, was located in a homologous of the P. aeruginosa atuB gene, that codifies citronellol deshydrogenase.

Comparison of PCR-based molecular markers for the characterization of Proteus mirabilis clinical isolates

Proteus mirabilis is one of the most important pathogens associated with complicated urinary tract infections (acute pyelonephritis, bladder infections, kidney stones) and bacteremia, affecting patients with anatomical abnormalities, immunodeficiency, and long-term urinary catheterization. For epidemiological purposes, various molecular typing methods, such as pulse-field gel electrophoresis (PFGE) or ribotyping, have been developed for this pathogen. However, these methods are labor intensive and time-consuming. We evaluated the discriminatory power of several PCR-based fingerprinting methods (RAPD, ISSR, ERIC-PCR, BOX-PCR and rep-PCR) for P. mirabilis clinical isolates. Typing patterns and clustering analysis indicated that RAPD, BOX-PCR and ERIC-PCR differentiated P. mirabilis strains from Escherichia coli, Hafnia alvei, and Morganella morganii. With the exception of rep-PCR, the methods gave medium to high discriminatory efficiency in P. mirabilis. In general, the results obtained with RAPD, BOX-PCR and ERIC-PCR were in good agreement. We concluded that a combination of ERIC-PCR and BOX-PCR results is a rapid and reliable alternative for discrimination among P. mirabilis clinical isolates, contributing to epidemiological studies.

Total protein electrophoresis and RAPD fingerprinting analysis for the identification of aeromonas at the species level

Fifteen well-defined strains of Aeromonas of thirteen species were analyzed by SDS protein electrophoretic analysis (SD-PAGE) and random amplified polymorphic DNA analysis (RAPD). The comparison between the patterns obtained by both methods allowed differentiating all the strains. Clusters formed by the unweighted pair group method with arithmetic averages applied to protein data correlates with the genetic and biochemical information about the species. The results show that protein fingerprinting has the potential to differentiate Aeromonas species, but the low qualitative variation indicates that this technique is not efficient of the characterization of strains within a species. Conversely, RAPD fingerprinting allows the identification of strains but the high variability limits its potential as an aiding method for species identification.

Evaluation of the genetic diversity among maize lines (Zea mays L.) by DNA fingerprinting analysis / Avaliação de diversidade genética entre linhagens de milho (Zea mays L.) por analisis de "DNA fingerprinting

Informativo DNA fingerprint profiles of eight homozygotic maize lines were obtained by the electrophoretic separation of DNA restriction fragments and the ir hybridization with the minisatellite probe R18.1. The analysis of the bandsharing frequencies allowed to identify all the lines and to estimate the genetic distances between them. The relationship obtained by DNA fingerprinting analysis of the eight inbreed lines was highly consistem with the ir genetical origin.

Perfis altamente informativos de oito linhagens homozigotas de milho foram obtidos através de análise de DNA fingerprinting, hibridizando-se os fragmentos de restrição com a sonda minisatélite R18,1. A análise de bandas coincidentes permitiu identificar todas as linhagens e estimar as distâncias genéticas entre elas. A relação entre as linhagens obtidas por esta análise é consistente com a origem genética das mesmas.