Detecção dos genes spvC e prot6E e avaliação da infecciosidade de Salmonella sp. em poedeiras comerciais
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Data
2019-03-06
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Universidade Federal de Goiás
Resumo
The pathogenesis of Salmonella includes different factors, such as plasmidial genes, which because they are mobile genetic mechanisms can increase the bacterial genetic diversity contributing to the modification of virulence and adaptation to the hosts. The present work was developed to detect the presence of the virulence genes spvC and prot6E in different serovars of Salmonella enteric present in the metropolitan region of Goiânia and to verify the ability of these serovars to express their pathogenicity in embryonated eggs, neonates and laying hens and to cause contamination in eggs in experimental models. In Experiment 1, isolates of Salmonella Enteritidis, Gallinarum, Heidelberg, Infantis, Schwarzengrund and Typhimurium were obtained from organs of sick bird, eggs and environment of poultry chain and were investigated the presence of spvC and prot6E genes by real-time PCR. Of the 47 isolates, 15 (31.9%) were positive for the spvC gene and five (10.6%) for the prot6E gene. It is concluded that Salmonella Enteritidis, Typhimurium and Gallinarum, isolated from the bird and eggs contain the spvC genes. The prot6E gene was detected in the serovars Salmonella Enteritidis, Heidelberg and Typhimurium from egg samples. The serovars of Salmonella Heidelberg, Infantis, Schwarzengrund and Typhimurium from environmental samples do not have the plasmid genes spvC and prot6E. In experiment 2, two isolates of Salmonella Gallinarum, one positive and one negative for the spvC gene, were inoculated into embryos and neonates of laying birds to investigate whether the presence of the spvC gene in the Gallinarum serovar is able to determine embryonic mortality, affect the quality of the neonate and chick, production parameters and cause systemic disease in young birds. It was observed high mortality of the groups inoculated with Salmonella Gallinarum in alantoid route with one and 14 days of incubation, independent of the presence of the spvC gene. No embryonic mortality, changes in neonatal weight / egg weight and changes in neonatal quality were observed for birds inoculated through a 19-day in air chamber. Salmonella Gallinarum without and with the spvC gene was recovered from the heart, spleen, liver and ceca of birds inoculated in the air chamber, whereas for the oral inoculated group, the pathogen without the gene was recovered only in the ceca and the pathogen with the gene was recovered from spleen and cecum. Salmonella inoculation led to decreased weight gain and altered biometry of the heart and intestine. It is concluded that Salmonella Gallinarum is capable of causing embryonic mortality in embryos inoculated with one and 14 days in the allantoic cavity. The presence of the spvC gene in Salmonella Gallinarum does not affect embryo mortality, incubation parameters and systemic dissemination for birds inoculated in the air chamber. For birds inoculated by the oral route, the presence of the spvC gene determines enteric and systemic infection, whereas the isolate without the gene remains restricted to the cecum. In Experiment 3, the Salmonella Heidelberg isolate positive for the prot6E gene in experiment 1 was inoculated in laying hens in the oral, intravaginal and intravenous routes in order to investigate their ability to cause clinical disease, egg and gastrointestinal tract contamination. The pathogen was isolated in the excreta, only 12 hours after inoculation in 33% of the birds inoculated from oral route and 66% of the birds inoculated intravaginal route. In the eggs, the pathogen was isolated at 24 and 48 hours, seven and 15 days. It is concluded that the presence of the prot6E gene in Salmonella Heidelberg is not sufficient to cause clinical salmonellosis in laying hens, but it determines contamination of the eggs and the gastrointestinal tract of chickens, regardless of the route of inoculation, oral, intravaginal and intravenous.
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Genes de virulência , Ovos , Postura , Sorovares , Eggs , Laying hens , Salmonella , Virulence genes
Citação
FIGUEIRA, S. V. Detecção dos genes spvC e prot6E e avaliação da infecciosidade de Salmonella sp. em poedeiras comerciais. 2019. 90 f. Tese (Doutorado em Ciência Animal) - Universidade Federal de Goiás, Goiânia, 2019.