The contribution of genes required for anaerobic respiration to the virulence of Salmonella enterica serovar Gallinarum for chickens

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A defective mutant of Salmonella enterica Serovar Gallinarum in cobalamin biosynthesis is avirulent in chickens

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Reversion to virulence evaluation of a 9R vaccine strain of Salmonella enterica serovar gallinarum in commercial brown layers

The live vaccine Cevac S. Gallinarum, made from a rough strain of Salmonella enterica subspecies enterica serotype Gallinarum is used for preventing fowl typhoid, a disease that still causes considerable economic losses in countries with a developing poultry industry. The objective of this paper was to evaluate a possible reversion to virulence of the strain used in a vaccine in commercial brown layers. Only Salmonella-free chicks were utilized. One hundred twenty (120) 12-day-old Dekalb brown layers divided in two trials were used. The first trial had six groups of 15 birds each. Birds of group 1 were vaccinated with 10 doses of Cevac S. Gallinarum subcutaneously and 10 doses orally, in a total of 20 doses of vaccine. Then the birds of groups 2, 3, 4, and 5 received inocula that contained feces and a pool of organs with fragments of liver, heart, spleen, and cecal tonsils obtained from the immediately previous group. The second trial had three groups with 10 birds each. Birds in group 7 received inocula containing a pool of organs from birds of group 5 from trial 1, whilst the birds in group 8 were vaccinated subcutaneously with one dose of vaccine. Both trials included negative control groups (6 and 9). Throughout the experimental period, birds were monitored for reactions to the vaccination on the site of administration, clinical signs, and post-mortem lesions. In each passage, in addition to the birds euthanized to provide the inocula material, two birds from each group were euthanized for assessment of possible lesions, and their organs (liver, heart, spleen and cecal tonsils) were cultured in an attempt to isolate the vaccine strain. Except for one bird from group 1, that had a local reaction on the site of vaccination - a small vesicle with less that 0.5 mm that persisted until the third day post vaccination -, no other bird had any local reaction to the vaccine or any visible clinical alteration. Birds in group 8 did not present any reaction or clinical alteration because of the vaccine. We only managed to re-isolate the vaccine strain in the inocula made from organs of birds in group 1. We confirmed the isolation by means of biochemical tests, serology, and acriflavine agglutination test. All other cultures made from organs or feces, from all the other experimental groups did not show any growth of the vaccine strain or any other Salmonella serovar, suggesting that the vaccinated birds did not shed the SG9R vaccine strain. No bird presented any clinical symptoms or died during the trials, and no gross lesions were observed in the post-mortem examinations. Under the controlled conditions and time-frame of the present experiment, it was possible to conclude that the rough 9R strain of Salmonella Gallinarum present in the vaccine Cevac S. Gallinarum (Ceva Campinas Ltda. - Campinas, SP - Brazil) did not revert to virulence.

Experimental infection of commercial layers using a Salmonella enterica serovar Gallinarum strain: Leukogram and serum acute-phase protein concentrations

The aim of the present study was to evaluate white blood cell counts and serum protein profiles of commercial layers experimentally infected with Salmonella Gallinarum (SG) in order to better understand the pathophysiology of the disease caused by this bacterium. 180 five-day-old commercial layers were divided into 3 groups (G); G1 and G2 received 0.2 mL of inoculate containing 3.3x10 8 CFU or 3.3×10 5 CFU SG resistant to nalidix acid (Nal r)/mL, respectively, directly into their crops. G3 group did not receive the inoculum. Birds were sacrificed 24 hours before (T1) and 24 hours after the infection (T2), and three (T3), five (T4), seven (T5), and ten (T6) days after the administration of the inoculum. White blood cell counts were carried out in a Neubauer hemocytometer and in blood smears. Serum protein concentrations, including acute-phase proteins, were determined using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Data were submitted to analysis of variance, and means were compared by Tukey's test (P <0.05). G1 and G2 groups presented higher leukocyte counts on T4 and T5, respectively, due to the increase of circulating lymphocytes and heterophils, with a significant difference relative to G3. In electrophoresis, an increase in the serum levels of ceruloplasmin, haptoglobin, and hemopexin and a decrease in transferrin, which are acute-phase proteins, was verified. IgA serum levels did not change; however, IgG concentration increased during the infection. In conclusion, the results provide information for the better understanding of the pathophysiology of fowl typhoid.

Experimental infection of commercial layers using a Salmonella enterica sorovar Gallinarum strain: Blood serum components and histopathological changes

The purpose of the study was to evaluate the blood serum components and histopathological findings of commercial layers experimentally infected with Salmonella Gallinarum (SG), the microorganism responsible for the fowl typhoid. 180 commercial layers were distributed into three groups (G): G1 and G2 received 0.2mL of inoculum containing 3.3x10 8 and 3.3x10 5 CFU of resistant SG to the nalidix acid (Nal r)/mL, respectively, directly into their crops; G3 did not receive the inoculum (control group). The birds were inoculated when they were 5 days old and the euthanasia was performed 24 hours before and after infection and 3, 5, 7 and 10 days after the administration of the inoculum. In each day of collection, blood samples were obtained for biochemical tests of the blood serum besides macroscopic and histopathological examination of the birds. Data were submitted to analysis of variance by the SAS statistical program and the means were compared by Tukeýs test (P<0,05). In the serum biochemical profile it was observed that the infection interfered in the values of total protein, albumin, calcium, phosphorus, cholesterol, triglycerides, GGT and ALT in the infected groups. The macroscopic examination showed hepatomegaly, alteration of the hepatic color and hemorrhagic spots in the kidneys of animals from G1. The histopathology showed degeneration of hepatocytes in G1 and G2 although other lesions like multifocal hepatic necrosis and inflammatory infiltrate on the liver and kidneys were restricted to G1. The alterations were more evident on G1 which received a higher concentration of bacteria/mL when compared to G2. The results showed that the correlation between biochemical alterations and macroscopic and histopathological lesions can assist the comprehension of the pathophysiology of fowl typhoid, supplying important information for the diagnosis and prognosis of this disease.

Polymerase chain reaction assay based on ratA gene allows differentiation between Salmonella enterica subsp. enterica serovar Gallinarum biovars Gallinarum and Pullorum

Salmonella Pullorum and Salmonella Gallinarum are classified as biovars of Salmonella enterica subsp. enterica serovar Gallinarum. These salmonellae are the causative agents of Pullorum disease and fowl typhoid, respectively, and are widely distributed throughout the world. Although many developed countries have eradicated these diseases from commercial poultry, they are still the cause of significant economic loss in developing countries. When serovar Gallinarum is isolated, it is difficult to immediately differentiate between biovars because they are antigenically identical by serotyping. However, they cause distinct diseases with different epidemiology, and therefore it is important to differentiate them. This may be done biochemically but takes 2 to 3 days. In the present study, S. Pullorum and S. Gallinarum whole genomes were compared, and 1 genomic region of difference, which is part of the ratA gene, was chosen as a molecular marker for a polymerase chain reaction assay to differentiate rapidly between these organisms. In all, 26 strains of S. Gallinarum and 17 S. Pullorum strains were tested and successfully differentiated by the assay. © 2013 The Author(s).

Utilização de um mutante atenuado de Salmonella enterica subesp. enterica sorovar GALLINARUM cobS cbiA para proteção de aves contra a infecção por Salmonella enterica subesp. enterica sorovares GALLINARUM E ENTERITIDIS

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Infecção experimental de aves de postura (Gallus gallus domesticus) por cepas de Salmonella enterica sorovar Gallinarum (SG), SGNalr SGcobS e SGcobScbiA: Anatomopatologia, hemograma e perfil bioquímico sérico

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Análise comparativa dos genomas de Salmonella enterica subsp. enterica sorovar Gallinarum biovares Gallinarum 287/91 e Pullorum 449/87 para identificação de regiões de diferenças (RODs)

Pós-graduação em Microbiologia Agropecuária - FCAV

Importância do flagelo para a patogenicidade de Salmonella enterica subespécie Enterica Sorovar Gallinarum biovar Gallinarum

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Diferenciação molecular entre Salmonella enterica subsp enterica sorovar Pullorum e Salmonella enterica subsp enterica sorovar Gallinarum

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação da patogenia de estirpes de Salmonella enterica SUBSP. enterica sorotipo Gallinarum biovar Gallinarum com os genes responsáveis pela expressão de flagelo ativos

Pós-graduação em Medicina Veterinária - FCAV

Imunidade de aves (Gallus gallus) para Salmonella enterica subesp. enterica Sorovar Gallinarum biovar Gallinarum

Pós-graduação em Medicina Veterinária - FCAV

Resposta imune celular e humoral em aves (Gallus gallus) vacinadas, antes e após o desafio com Salmonella enteritidis

Pós-graduação em Medicina Veterinária - FCAV

Seroprevalence of salmonella and mycoplasma in commercial broilers, backyard chickens, and spent hens in the region of Triangulo Mineiro, state of Minas Gerais, Brazil

Avian salmonellosis and mycoplasmosis are infectious diseases that, in addition of causing lack of flock uniformity, represent a hazard to human health. The objective of the present study was to evaluate the seroprevalence of mycoplasmosis and salmonellosis in commercial broilers, backyard chickens, and spent hens slaughtered at a processing plant with local health inspection in Uberlandia, MG, Brazil. A total of 210 samples were randomly collected at the time of bleeding. Samples were submitted to rapid plate serum agglutination test (RSA) for the classification of Salmonella pullorum, Salmonella gallinarum, Mycoplasma gallisepticum and Mycoplasma synoviae. In order to increase result specificity, mycoplasmosis-positive samples were submitted to hemagglutination inhibition test (HI). No samples presented detectable antibodies against Salmonella pullorum or Salmonella gallinarum in the RSA test. Only Mycoplasma synoviae was detected in 14% of the backyard chickens and 0.74% in commercial broilers, whereas no antibodies were detected in spent hens. The seroprevalence rates found in the present study emphasize the need of keeping chicken flocks free from disease using effective biosafety systems.