Necrotic enteritis (NE), a devastating enteric disease caused by Clostridium perfringens type A, contributes to the losses of 6 billion dollars worldwide per year and is currently being considered as a major global threat to the poultry industry. In past decades, it has been well-controlled by ineed antimicrobial growth promoters (AGPs). The withdrawal of AGPs due to antibiotic-resistance concerns resulted in a spike in NE incidence and led to the re-emergence of NE in the modern broiler production system. To unveil the association of toxin genes of C. perfringens, particularly for netB, with clinical NE, a self-designed qPCR primer set targeting netB was developed to qualify and quantify netB in NE-producing and non-NE-producing isolates. The netB was demonstrated to exist in the majority of C. perfringens type A isolates. The presence and the amount of netB were not significantly different between two types of isolate, indicating that those indicators are insufficient to predict an association with the pathogenicity of NE. The virulence of netB is suggested to be expressed or triggered under certain conditions, further promoting NE. A side by side trial was implemented with different combinations of netB-positive C. perfringens (CP1) and two predisposing factors to assess their role in NE development. Both CP1 and predisposing factor(s) are required for consistent NE reproduction, and particularly, Eimeria exerts significant effects on NE induction. The use of CP1 without a predisposing factor failed to induce NE. The severity and incidence of NE were positively correlated with the number of predisposing factors given in the NE induction. Analyzing gut microbiota in chickens challenged with CP1 and/or Eimeria by metagenomic sequencing, significant overgrowth of Clostridium sensu stricto 1, the genus contains C. perfringens, was associated with NE. Eimeria infection precedent to CP1 challenge had a synergistic effect on the overrepresentation. In addition to C. perfringens, the other member under Clostridium sensu stricto 1 was found to participate in NE development. Given supplementary dose of 0.4 kg/ton in feed, lauric acid neither exerted the inhibitory effect against proliferation of Clostridium sensu stricto 1 and C. perfringens nor reduced the incidence and severity of NE.

Necrotic enteritis (NE) is a disease that negatively affects broiler performance and has increasingly become a problem with the reduced use of antibiotics. There is increased interest to utilize alternative methods including coccidial vaccines and direct fed microbials (DFM) to reduce or prevent NE. Additionally, it has been demonstrated that reduced dietary Ca can reduce NE mortality. The objective of the first study was to examine the effects of Bacillus subtilis (DFM) in combination with attenuated (AV) and non-attenuated (NV) coccidial vaccines in broilers with NE. The objective of the second study was to determine the effects of DFM, antibiotic (BMD) or negative control (NC) with standard dietary Ca (0.9%) or below standard Ca (0.75%, 0.6%) in broilers with NE. To induce a natural NE occurrence, birds were vaccinated with the appropriate coccidial vaccine and then placed on reused litter from a previous flock exhibiting NE lesions and mortality. In the first trial DFM reduced BW and BW gain (P ≤ 0.05) during the starter phase (0 to 14 d). The addition of a DFM in the AV group resulted in decreased (P ≤ 0.05) BW gain and BW at 42 d. The DFM in the NV group resulted in improved (P ≤ 0.05) mortality corrected feed conversion ratio from 0 to 42 d. Overall, with a natural NE occurrence, the effect of DFM was variable depending on what type of coccidial preventative was utilized and was beneficial when used with NV. In the second trial BW and BW gain were increased in broilers fed 0.60% dietary Ca and DFM compared to 0.90% Ca and NC (P ≤ 0.05). Broilers fed 0.60% Ca had reduced NE mortality compared to broilers fed 0.90% Ca (P ≤ 0.05). Reducing dietary Ca to below industry standards was able to lessen the severity of NE though the addition of DFM was needed to improve BW. Overall, with a natural NE occurrence, the DFM was beneficial when used with NV and in diets with 0.6% dietary Ca. / Doctor of Philosophy / Necrotic enteritis (NE) is caused by the bacterium Clostridium perfringens and is a disease that reduces growth of broiler chicks and has increasingly become a problem in the chicken industry with the reduced use of antibiotics. Coccidiosis is a protozoal disease that causes intestinal damage and predisposes broilers to developing NE. Prevention of coccidiosis can be through medication or coccidial vaccines. Probiotics or direct fed microbials (DFM) have demonstrated the potential to reduce both coccidiosis and NE symptoms. Additionally, it has been shown that reducing the amount of calcium (Ca) in the diet can reduce chick death from NE. The first study examined the effects of a beneficial bacterium, Bacillus subtilis (DFM) in combination with two types of coccidial vaccines, attenuated (AV) and non-attenuated (NV). The second study investigated DFM with standard dietary Ca (0.9%) or below standard Ca levels (0.75%, 0.6%). To induce a "natural" NE disease occurrence, birds were vaccinated with the appropriate coccidial vaccine and then placed into pens. Pens contained reused litter from a previous flock of birds with NE (contained spores of Clostridium perfringens). In the first trial DFM reduced body weight of broilers during the first two weeks (P ≤ 0.05). The DFM decreased (P ≤ 0.05) BW gain and BW in the AV group but improved feed efficiency in the NV group (P ≤ 0.05). In the second trial BW and BW gain were increased in broilers fed DFM and lower Ca diets (0.6%) compared to those fed the standard (0.90%) Ca diets without DFM (P ≤ 0.05). Dead birds were reduced when broilers were fed lower Ca diets (0.6%) compared to broilers fed standard (0.90%) Ca diets (P ≤ 0.05). In conclusion, the DFM was beneficial when used with NV and in diets with lower Ca (0.6%) during a natural NE occurrence.

Chickens genetically selected for low (LA) or high (HA) antibody response to sheep red blood cells (SRBC) displayed a correlated change in major histocompatibility complex (MHC), so that LA chickens were 96% B¹³ and HA chickens were 96% B²¹. During a clinical outbreak of necrotic enteritis, B²¹B²¹ genotypes experienced significantly less mortality (6% vs. 13 %) compared to B¹³B¹³ genotypes. A study was carried out to assess immunological differences between LA and HA lines during exposure to Clostridium perfringens. In Experiment 1, chickens were orally gavaged with a low (10⁷ CFU/mL) or high (10⁹ CFU/mL) dose of C. perfringens. In Experiment 2, chickens were orally gavaged with live coccidia oocysts on experiment d 1, followed by 10⁷ CFU/mL C. perfringens on d 5. Unfortunately, establishment of necrotic enteritis infection was unsuccessful in both experiments as evidenced by lack of significant intestinal lesions, as well as no negative effect on bird performance. In an ex vivo study, peripheral blood mononuclear cells (PBMCs) were isolated from each genetic line, cultured, stimulated with LPS (4 h), and exposed to varying concentrations of C. perfringens α-toxin (1, 10, 100, 1000 U/L) for 2 and 4 h. Evaluation of cellular proliferation, percent cytotoxicity and immunological gene expression was carried out in a variety of experiments. Genetic lines were found to be highly divergent in all analyses. / Master of Science

Clostridium perfringens type E iota toxin is implicated in some cases of fatal diarrhea in calves, lambs, and guinea pigs. A crossreacting "iota-like" toxin, produced by Clostridium spiroforme, is responsible for antibiotic-associated and weaning related enterotoxemias of rabbits. Antisera developed against culture supernatant of either organism neutralized the biological activity of iota or iota-like toxin. By using C. spiroforme antiserum and crossed immunoelectrophoresis (crossed IEP), we found two cross-reacting antigens in C. perfringens type E supernatants. C. perfringens types A, B, C, and D, which do not produce iota toxin, did not cross-react with C. spiroforme antiserum. To determine if either antigen had iota toxin activity, we separated the cross-reacting antigens of C. perfringens by preparative isoelectric focusing (IEF) and tested all IEF fractions for biological activity in guinea pigs and mice. The fraction containing the faster-migrating antigen seen in crossed IEP, designated iota b (i_b), had some guinea pig dermonecrotic and mouse lethal activity. Other fractions, including the one containing the slower migrating iota a (i_a) antigen, had little to no biological activity. When fractions containing i_a and i_b were mixed, there was an 8 and 25 fold increase in mouse lethal and dermonecrotic titers, respectively. Activity was neutralized by C. perfringens type E or C. spiroforme antisera and other fractions, when mixed with i_a or i_b, did not have a synergistic effect. Both components of C. perfringens iota toxin were purified using ammonium sulfate precipitation, DEAE anion exchange chromatography, preparative IEF, Sephadex G-100 gel filtration, and flatbed electrophoresis to yield a 12 and 5% final recovery of i_a and i_b, respectively. Each protein was homogeneous by SDS PAGE, gradient PAGE, and crossed IEP using homologous antiserum. There was at least an 8 fold increase in mouse lethal titer and 64 fold increase in dermonecrotic titer when equimolar amounts of i_a and i_b were mixed. Monospecific antisera against purified i_a and i_b neutralizd the iota or iota-like activity of crude supernatants. A sensitive and specific ELISA was developed using monospecific and C. spiroforme antisera. The i_a and i_b proteins have a pI of 5.2 and 4.2 and molecular weights of 48,000 and 71,000 (SDS PAGE), respectively. The i_a protein is heat stable (85° C/15 min) while i_b lost its activity at 55°C. Amino terminus sequencing revealed that both proteins were blocked by an unknown functional group(s). Purified i_a, but not i_b, has ADP-ribosylating activity specific poly-L-arginine in vitro. Recent evidence suggests that nonmuscle actin, involved in the cytoskeletal structure of eucaryotic cells, may act as the in situ acceptor. / Ph. D.

Orientador: Tereza Cristina Cardoso da Silva / Banca: José Antônio Jerez / Banca: Iveraldo dos Santos Dutra / Resumo: O Complexo de Enterite de Perus (PEC) tem sido incriminado como uma das maiores causas de perdas econômicas em outros países. Neste estudo, foi demonstrado causando diarréia, perda de peso e na maioria das vezes alta mortalidade em perus acometidos de enterite com 30-120 dias de idade de uma determinada região produtora no Brasil. A RT-PCR foi aplicada em suspensões de intestinos (SI) (n=2), respectivos conteúdos intestinais (CI) (n=2), bursa de Fabrícius (BF), fezes (F) (n=5) e swabs cloacais (SC) (n=44), para amplificar a região conservada 3'UTR e gene do nucleocapsídeo de TCoV. Os exames de histopatologia e imunohistoquímica direta foram realizados para detectar o antígeno TCoV a partir de lâminas de intestinos e bursas infectados. Todos os resultados obtidos nos tecidos marcados, revelaram lesões sugestivas de terem sido causadas pela infecção por TCoV. A marcação positiva da imunohistoquímica direta estava presente em todas as lâminas de intestinos, entretanto, todas as BF analisadas foram negativas. Os achados de RT-PCR foram positivos para TCoV em todas as amostras de fezes e 27,27% das amostras de SC foram positivas para a região 3'UTR e região TCoV nucleocapsídeo. As amostras de soro (n=200), foram positivas para TCoV, com títulos variando de 2.0Log a 8.0Log usando o ELISA comercial IDEEX para IBV. Finalmente, o melhor material de campo para o diagnóstico de TCoV foram as fezes (F) e/ou suspensão de intestinos (SI), resultando na primeira descrição de perus com quadro agudo de enterite acometidos por coronavirus Grupo 3 no Brasil. / Abstract: The Poult Enteritis Complex (PEC) has been incriminated as the major cause of losses in other countries, and especially, in this study, was described causing diarrhea, weight gain and most of the time, high mortality. In this study, it was performed the turkey coronavirus (TCoV) detection from 30-120 day old affected poults from a particular producer region in Brazil. The RT-PCR was applied in intestines suspensions (IS) (n=2), respective intestines contents (IC) (n=2), bursa of Fabrícius (BF), faecal droppings (FD) (n=5) and cloacal swabs (CS) (n=44) to amplify the 3þUTR conserved region and TCoV nucleocapsid gene. The histopathological and direct immunohistochemical examinations were performed to detect the TCoV antigen from infected intestine and bursa slides. All results obtained from stained tissues, revealed lesions described to be caused by TCoV infection. The direct immunohistochemical positive signal was present in all intestine slides, however all BF analysed were negative. RT-PCRs findings were positive for TCoV in all FD samples, and 27,27% of CS analysed were positive for 3þUTR and TCoV nucleocapsid region. The sera samples (n=200) were positive for TCoV, with titers range from d 2.0Log to 8.0Log using the IDEEX commercial ELISA for IBV. Finally, the best field material for TCoV diagnosis was FD and/or intestine suspensions (IS), resulting in a first describe of TCoV affecting poults in Brazil. / Mestre

Made available in DSpace on 2014-06-11T19:27:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-10-03Bitstream added on 2014-06-13T20:16:25Z : No. of bitstreams: 1 teixeira_mcb_me_araca.pdf: 1608069 bytes, checksum: 5e594d70a730c7e0223fb2453f313c44 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O Complexo de Enterite de Perus (PEC) tem sido incriminado como uma das maiores causas de perdas econômicas em outros países. Neste estudo, foi demonstrado causando diarréia, perda de peso e na maioria das vezes alta mortalidade em perus acometidos de enterite com 30-120 dias de idade de uma determinada região produtora no Brasil. A RT-PCR foi aplicada em suspensões de intestinos (SI) (n=2), respectivos conteúdos intestinais (CI) (n=2), bursa de Fabrícius (BF), fezes (F) (n=5) e swabs cloacais (SC) (n=44), para amplificar a região conservada 3`UTR e gene do nucleocapsídeo de TCoV. Os exames de histopatologia e imunohistoquímica direta foram realizados para detectar o antígeno TCoV a partir de lâminas de intestinos e bursas infectados. Todos os resultados obtidos nos tecidos marcados, revelaram lesões sugestivas de terem sido causadas pela infecção por TCoV. A marcação positiva da imunohistoquímica direta estava presente em todas as lâminas de intestinos, entretanto, todas as BF analisadas foram negativas. Os achados de RT-PCR foram positivos para TCoV em todas as amostras de fezes e 27,27% das amostras de SC foram positivas para a região 3`UTR e região TCoV nucleocapsídeo. As amostras de soro (n=200), foram positivas para TCoV, com títulos variando de 2.0Log a 8.0Log usando o ELISA comercial IDEEX para IBV. Finalmente, o melhor material de campo para o diagnóstico de TCoV foram as fezes (F) e/ou suspensão de intestinos (SI), resultando na primeira descrição de perus com quadro agudo de enterite acometidos por coronavirus Grupo 3 no Brasil. / The Poult Enteritis Complex (PEC) has been incriminated as the major cause of losses in other countries, and especially, in this study, was described causing diarrhea, weight gain and most of the time, high mortality. In this study, it was performed the turkey coronavirus (TCoV) detection from 30-120 day old affected poults from a particular producer region in Brazil. The RT-PCR was applied in intestines suspensions (IS) (n=2), respective intestines contents (IC) (n=2), bursa of Fabrícius (BF), faecal droppings (FD) (n=5) and cloacal swabs (CS) (n=44) to amplify the 3þUTR conserved region and TCoV nucleocapsid gene. The histopathological and direct immunohistochemical examinations were performed to detect the TCoV antigen from infected intestine and bursa slides. All results obtained from stained tissues, revealed lesions described to be caused by TCoV infection. The direct immunohistochemical positive signal was present in all intestine slides, however all BF analysed were negative. RT-PCRs findings were positive for TCoV in all FD samples, and 27,27% of CS analysed were positive for 3þUTR and TCoV nucleocapsid region. The sera samples (n=200) were positive for TCoV, with titers range from d 2.0Log to 8.0Log using the IDEEX commercial ELISA for IBV. Finally, the best field material for TCoV diagnosis was FD and/or intestine suspensions (IS), resulting in a first describe of TCoV affecting poults in Brazil.

Orientador: Tereza Cristina Cardoso da Silva / Resumo: Coronavirus são RNA vírus sentido positivo, envelopados, comumente associados a infecções brandas em aves e mamíferos. A infecção por CCoV é comum em cães jovens, principalmente em animais que vivem em canis e abrigos, associada à ocorrência de diarreia branda e autolimitante, causada pela infecção das células das vilosidades do intestino delgado. São conhecidos dois genótipos: CCoV-I e CCoV-II, o qual é subdividido em CCoV-IIa e CCoV-IIb. O CCoV-IIa, é uma variante altamente patogênica associada à doença sistêmica e acentuada linfopenia. Diferentemente de outros CCoV realiza viremia e, assim, determina a disseminação do vírus para diversos órgãos, incluindo tecidos linfóides. Nesse sentido, o envolvimento da infecção de macrófagos correlacionada à gravidade da doença e linfopenia, vem sendo sugerido. Este trabalho teve por objetivo promover a infecção de macrófagos caninos derivados de monócitos sanguíneos e avaliar a replicação viral, despolarização da membrana mitocondrial e os complexos da cadeia respiratória mitocondrial às 6, 12, 18 e 24 horas pós-infecção. A estatística descritiva incluiu média ± desvio padrão (s.d.). As médias foram comparadas através da análise de variância, ANOVA. Foi possível observar que a infecção por CCoV induziu a liberação de novas partículas virais entre 18 e 24 horas pós-infecção. Ainda, a infecção viral esteve associada à despolarização e disfunção da membrana mitocondrial, afetando o complexo III da cadeia respiratória. Desse modo, acredit... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Coronaviruses are enveloped positive-sense RNA viruses commonly associated with mild infections in birds and mammals. CCoV infection is common in young dogs, especially kennel and shelter animals, associated with the occurrence of mild, self-limiting diarrhea caused by infection of small intestinal villus cells. Two genotypes are known: CCoV-I and CCoV-II, which is subdivided into CCoV-IIa and CCoV-IIb. CCoV-IIa is a highly pathogenic variant associated with systemic disease and marked lymphopenia. Unlike other CCoV it carries viremia and thus determines the spread of the virus to various organs including lymphoid tissues. In this sense, the involvement of macrophage infection correlated with disease severity and lymphopenia has been suggested. This study aimed to promote the infection of canine macrophages derived from blood monocytes and to evaluate viral replication, mitochondrial membrane depolarization and mitochondrial respiratory chain complexes at 6, 12, 18 and 24 hours post-infection. Descriptive statistics included mean ± standard deviation (s.d.). Means were compared by analysis of variance, ANOVA. It was observed that CCoV infection induced the release of new viral particles between 18 and 24 hours after infection. Moreover, viral infection was associated with depolarization and mitochondrial membrane dysfunction, affecting respiratory chain complex III. Thus, CCoV is believed to induce mitochondrial bioenergetic failure, acting as a decoupler of the respiratory c... (Complete abstract click electronic access below) / Doutor

Ziel dieser Arbeit war es, eine Reihe von 17 ausgewählten Kohlehydraten auf deren Fähigkeit zu bewerten, die Adhärenz humanpathogener Enteritis-/Diärrhoe-Erreger zu reduzieren oder gänzlich zu verhindern. Gestestet wurde die Adhärenz an Kryoschnitten humaner Darmbiopsien. Hierbei wurde die bakterielle Adhäsion ohne Zusatz der Kohlehydrate bestimmt und als Vergleichswert gegenüber dem Ansatz mit Zusatz der Kohlehydrate herangezogen. Dabei kamen Stämme folgender Spezies zum Einsatz: entero-aggregative E. coli, entero-hämorrhagische E. coli, entero-pathogene E. coli, entero-toxigene E. coli, Salmonella enterica Serovar Typhimurium und Shigella flexneri. Als Positiv-Kontrolle wurde Citrobacter freundii verwendet. / Anti-adhesion therapy of bacterial infections

O setor avícola apresenta o maior crescimento em volume produzido dentre todos os setores cárneos no Brasil. A grande participação dos produtos avícolas na alimentação humana somada ao risco do desenvolvimento de resistência bacteriana, levaram a União Européia (UE) a abolir utilização de antimicrobianos como aditivos e de forma profilática na ração de animais. A remoção dos aditivos associada ao sistema de criação intensivo acabaram por fazer que doenças, até então consideradas controladas, se tornassem reemergentes. A enterite necrótica aviária (NE) é considerada um exemplo. De forma geral, condições estressoras predispõem ao desenvolvimento de doenças, sendo o calor um dos estressores mais comuns que ocorrem em granjas aviárias. Este estudo enfoca o efeito do estresse térmico por calor (35±1ºC) sobre o desenvolvimento da NE em frangos de corte. Para isso, 60 frangos de corte machos foram divididos em 6 grupos experimentais: 1 Grupo Controle; 2 Grupo Controle Estressado (C/HS35); 3 Grupo Tioglicolato (T); 4 Grupo Tioglicolato Estressado (T/HS35); 5 Grupo Infectado (I); 6 Grupo Infectado Estressado (I/HS35). A infecção experimental com Clostridium perfringens foi feita por via oral, com a bacteria em meio de cultura misturada a ração, do 15º ao 21º dia de vida nos grupos I e I/HS35. O estresse por calor (35±1º C) foi realizado do 14º ao 21º dia de vida das aves dos grupos estressados. Durante todo período experimental os animais foram mantidos em isoladores. Em relação aos animais não estressados, os animais submetidos ao estresse por calor apresentaram: 1- menor escore lesional macro e microscópico no intestino delgado; 2- maior concentração de IgA no lavado intestinal do duodeno; 3 - menor concentração de IgA no jejuno; 4 - redução dos níveis séricos de IgA e IgY; 5 - maior concentração sérica de IgM; 6 - diminuição qualitativa evidente dos heterofilos intestinais em relação aos animais infectados e estressados. Portanto, mostrou-se que o estresse por calor apresentou efeito imunomodulador importante, ao reduzir a inflamação intestinal. Este achado associa-se provavelmente à diminuição da imunidade inata por redução da migração de heterófilos para a mucosa intestinal, desta forma prevenindo a manifestação de um um quadro clínico mais grave de NE, fato associado à diminuição das lesôes desencadeadas pelo processo inflamatório heterofílico. / The poultry sector presented the highest growth in the volume of production among all meat sectors in Brazil. The great participation of poultry products on human diet together with the risk of food and environmental contamination by resistant bacteria led the European Union (EU) countries to abolish the use of antibiotics as feed additives in animal production. This fact associated with the intensive farming system are being reported as responsible for the re-emergence of some already controlled diseases. The avian necrotic enteritis (NE) exemplify such an effect. Generally, stressful conditions are predisponent factors for disease development; heat stress is one of the most common stressor in poultry farms. This study focuses on the effects of heat stress (35 ± 1 º C) on the development of NE in broilers. For this purpose, 60 male broilers were divided into 6 groups: 1 - control group, 2 - stressed control group (C/HS35) 3 - thioglycolate group (T) 4 - thioglycolate stressed group (T/HS35); 5 - infected group (I) 6 - infected stressed group (I/HS35). Experimental infection with Clostridium perfringens, grown in thioglycollate broth medium, was given through the feed to the birds of groups I and I/HS35 from the 15th to 21st days of life. The heat stress (35 ± 1 °C) was induced continuously from the 14th to the 21st day of life in birds of the stressed groups. Throughout the experimental period the animals were kept in isolators. Compared to non-stressed animals, broilers subjected to heat stress showed: lower gross and microscopic score lesions in the small intestine; increased concentrations of IgA in duodenal lavage and decreased IgA concentrations in the jejunum; smaller concentrations of serum IgA and IgY; increased concentration of serum IgM; reduction in gut number of heterophils in the thioglycolate treated and in the infected groups. Therefore, this experimental model showed that heat stress presented a significant immunomodulatory role on the induced NE, most probably because it reduced intestinal inflammation via decrease in heterophils migration to the intestinal mucosa, which in turn might had reduced tissue damage during infamation, hence preventing the development of a more severe form of NE.

Doenças infecciosas entéricas das aves comerciais apresentam uma etiologia complexa e são distribuídas mundialmente, acarretando elevadas perdas econômicas. Aliadas à possibilidade de infecções únicas ou concomitantes entre diversos patógenos, as gastroenterites podem se refletir em outros sistemas, contribuindo ainda mais para a queda da performance dos lotes. Recentemente, foi detectado um coronavírus no conteúdo intestinal de aves apresentando despigmentação e diarréia. Este vírus, denominado de CECoV (chicken enteric coronavírus) é sugestivo de pertencer ao grupo 2, divergente dos demais coronavírus comuns em aves, pertencentes ao grupo 3 do gênero Coronavirus. No Brasil, há uma grande necessidade no conhecimento acerca da participação dos agentes virais nas diarréias de aves, sendo este um passo fundamental para o estabelecimento de medidas profiláticas específicas e para a exportação de produtos avícolas. Este estudo teve por objetivos detectar este coronavírus do grupo 2 em aves de corte, poedeiras comerciais e matrizes com e sem diarréia pela técnica de PCR dirigida ao gene codificador da RNA-polimerase RNA-dependente (gene RdRp) dos coronavírus do grupo 2, estabelecer a relação genealógica entre diversas amostras detectadas deste vírus com base em seqüências dos genes RdRp, gene codificador da proteína de espícula (S), gene codificador da proteína hemaglutinina-esterase (HE), gene 5, gene 3 e região 3\'UTR e realizar o diagnóstico diferencial com reovírus, rotavírus, variedades enterotrópicas do vírus da bronquite infecciosa das galinhas (VBIG), astrovírus e adenovírus. O coronavírus CECoV foi detectado em 25 de 119 amostras de conteúdo entérico de aves de corte, matrizes e poedeiras com e sem diarréia, em diversas granjas produtoras no Brasil, pela técnica da reação em cadeia pela polimerase dirigida ao gene RdRp. O CECoV tem papel como agente primário e secundário em processos patológicos do trato digestório de aves e, ao serem analisadas filogeneticamente, diferentes amostras de CECoV formaram um grupo único com base no gene RdRp dentro do grupo 2 do gênero Coronavirus, possuindo homologia com coronavírus do grupo 3 na região 3\'UTR, sendo sua origem sugerida como um evento de recombinação entre coronavírus dos grupos 2 e 3. Através do estabelecimento de uma rotina de diagnóstico diferencial, as freqüências de ocorrência de vírus entéricos em aves de produção criadas nas 119 granjas no Brasil foram: rotavírus=48,74%, reovírus=2,52%, VBIG=65,54%, CECoV=21% e astrovírus=3,36%. / Infectious enteric diseases in poultry have a complex etiology and a worldwide distribution, causing large economic losses. Along with the possibility of single or multiple infections by different pathogens, enteric diseases may also be reflected in other systems, contributing even more to the fall of performance in the affected flocks. Recently, a coronavirus was detected in the intestinal contents of chickens with depigmentation and diarrhea. This virus, named CECoV (chicken enteric coronavirus), has been suggested as belonging to group 2, divergent of the common avian coronaviruses, which belongs to the group 3 of the genus Coronavirus. In Brazil, there is a great need for the knowledge on the role of viral agents in diarrhea of poultry, what is a fundamental step for the establishment of specific prophylactic measures and for the exportation of poultry-derived products. The present study aimed the detection of this group 2 coronavirus in broilers, laying hens and breeders with and without diarrhea using a PCR targeted to the gene coding for the RNA-dependent RNA-polymerase (RdRp) of group 2 coronaviruses, the establishment of the genealogical relationship among the different strains detected based on sequences of the RdRp, the genes coding for the spike protein (S gene), hemagglutinin-esterase protein (HE gene), gene 5, gene 3 and the 3\' UTR and the differential diagnosis with reovirus, rotavirus, enterotropic strains of infectious bronchitis virus (IBV), astrovirus and adenovirus. CECoV was found in 25 out of 119 samples of enteric contents of broilers, breeders and laying hens in different farms in Brazil using the PCR to the RdRp. CECoV has a role as a primary and secondary pathogen in pathological processes of the enteric tract of poultry and the phylogenetic analysis showed that different strains of CECoV formed an unique cluster based on the RdRp inside the group 2 of coronaviruses, harboring homology with group 3 coronaviruses in the 3\'UTR, being its origin suggested as a recombination event between coronaviruses of groups 2 and 3. By the establishment of a routine of diagnosis, the frequencies of enteric viruses in the 119 poultry farms surveyed were: rotavirus = 48.74%, reovirus = 2.52%, IBV = 65.54%, CECoV = 21% and astrovirus = 3.36%.