Individual variation is the key to the development of a vaccine against Staphylococcus aureus: a comparative study between mice lineages

Bacterial infections occur worldwide and are a major public health problem. Among pathogens, Staphylococcus aureus is the main causative agent of bacterial diseases in the world. This study aimed to evaluate which components of the immune system could act protectively against a S. aureus infection in intradermally immunized mice. C57BL/6 and A/j mice were immunized intradermally with S. aureus inactivated by heat and then challenged with viable strains in an air pouch model. At 6, 12, and 24 h after the challenge, euthanasia was performed, and the cellular profile of the inflammatory infiltrate, cytokines, and the bacterial load were evaluated in the air pouch lavages. Immunized mice demonstrated that the intradermal immunization with S. aureus promoted protection in C57BL/6 mice by reducing the bacterial, which was correlated with increased serum concentration of IgG antibodies (IgG1 and IgG2a) against S. aureus. The increase in IgG2a antibody levels was correlated with a decrease of bacterial load in intradermally immunized C57BL/6 mice, along with production of IL-17A at the inflammation site, as well as IgG1consumption. Similar results were not found in the A/j lineage. In conclusion, a vaccine against S. aureus should focus more on the individual characteristics of the host because it is a determinant factor for the success of the immunization.

Morfometria de frutos e sementes e germinação de carobinha (Jacaranda decurrens subsp. symmetrifoliolata Farias & Proença), após o armazenamento / Fruit and seed morphometry and germination of "carobinha" (Jacaranda decurrens subsp. symmetrifoliolata) seeds after storage

O trabalho teve como objetivos avaliar a morfometria dos frutos e sementes de carobinha (Jacaranda decurrens subsp. symmetrifoliolata) e o efeito de temperaturas na germinação de sementes armazenadas em ambiente sem controle de temperatura e umidade relativa. O estudo foi realizado no Laboratório de Sementes da UFGD, Dourados, MS. Em amostra de 120 frutos e de 550 sementes foi determinado: o comprimento, a largura, a espessura, o número de sementes por fruto, e a massa dos frutos. A germinação foi estudada após três períodos de armazenamento das sementes (120, 480 e 720 dias) a temperatura ambiente e sob quatro temperaturas de germinação: três constantes (18, 25 e 30ºC) com luz contínua e sob condição de tempera alternada, 20-30ºC, com fotoperíodo de 12 horas. O delineamento experimental foi inteiramente ao acaso, em arranjo fatorial 3 x 4, com quatro repetições. As variações nas medidas de frutos e sementes representam indício da alta variabilidade genética populacional. As sementes armazenadas por 120 dias e submetidas à germinação na temperatura de 25ºC resultaram em 69,4% de germinação e índice de velocidade de germinação - IVG, de 0,983. Sob temperaturas de germinação de 30ºC, constante, e de 20-30ºC, alternada, obtiveram-se 63,9% e 63,8% de germinação e 0,486 e 0,413 de IVG, respectivamente. Sob temperatura de 18ºC a germinação foi lenta e menor, 27,7% e IVG de 0,119. As sementes armazenadas por 480 e 720 dias não germinaram. Com base no comportamento fisiológico das sementes é possível classificar Jacaranda decurrens subsp. symmetrifoliolata como espécie intermediária (entre ortodoxa e recaucitrante).

This study aimed to evaluate the morphometry of fruits and seeds of Jacaranda decurrens subsp. symmetrifoliolata ("carobinha") and the effect of temperature on the germination of seeds that were stored in environment without controlled temperature and relative humidity. The study was carried out at Seed Laboratory of Federal University of Grande Dourados, Mato Grosso do Sul, Brazil. For a sample of 120 fruits and 550 seeds, the following variables were determined: length, width and thickness, besides the number of seeds per fruit and fruit biomass. Germination was studied after three seed storage periods (120, 480 and 720 days) at environment temperature and four germination temperatures: three constant temperatures (18, 25 and 30ºC) with continuous light, and one alternating temperature, 20-30ºC, with 12-hour photoperiod. Experimental design was completely randomized, in 3 x 4 factorial schemes, with four replicates. The variations in the measures of fruits and seeds evidence a high genetic variability in the population. The seeds stored for 120 days and subjected to germination test at 25ºC resulted in 69.4% germination and germination velocity index - GVI of 0.983. At 30ºC, constant temperature, and 20-30ºC, alternating temperature, germination was 63.9% and 63.8% while GVI was 0.486 and 0.413, respectively. At 18ºC, germination was slow and lower, 27.7%, and GVI was 0.119. Seeds stored for 480 and 720 days did not germinate. Based on the physiological behavior of seeds, it is possible to classify Jacaranda decurrens subsp. symmetrifoliolata as an intermediate species (between orthodox and recalcitrant).