Sensitivity of Quails (Coturnix coturnix), Siskins (Carduelis spinus), and Frogs (Rana ridibunda) to West Nile Virus.

The level of viremia and features of the course of experimental infection caused by West Nile virus were studied in two species of migratory birds, siskins Сarduelis spinus and quails Coturnix coturnix, and in one species of amphibians, frogs Rana ridibunda. In quails, the virus caused a fatal disease; histological analysis revealed pathological changes in the heart, kidneys, liver, and brain stem. In siskins and frogs, virus antigen was detected in cloacal smears despite the absence of clinical manifestations, the level of viremia was sufficient to infect insect vectors during bloodsucking. These findings suggest that siskins and frogs can be potential reservoirs of West Nile virus and play a role in its circulation.

The RNA-Binding Protein of a Double-Stranded RNA Virus Acts like a Scaffold Protein.

Infectious bursal disease virus (IBDV), a nonenveloped, double-stranded RNA (dsRNA) virus with a T=13 icosahedral capsid, has a virion assembly strategy that initiates with a precursor particle based on an internal scaffold shell similar to that of tailed double-stranded DNA (dsDNA) viruses. In IBDV-infected cells, the assembly pathway results mainly in mature virions that package four dsRNA segments, although minor viral populations ranging from zero to three dsRNA segments also form. We used cryo-electron microscopy (cryo-EM), cryo-electron tomography, and atomic force microscopy to characterize these IBDV populations. The VP3 protein was found to act as a scaffold protein by building an irregular, ∼40-Å-thick internal shell without icosahedral symmetry, which facilitates formation of a precursor particle, the procapsid. Analysis of IBDV procapsid mechanical properties indicated a VP3 layer beneath the icosahedral shell, which increased the effective capsid thickness. Whereas scaffolding proteins are discharged in tailed dsDNA viruses, VP3 is a multifunctional protein. In mature virions, VP3 is bound to the dsRNA genome, which is organized as ribonucleoprotein complexes. IBDV is an amalgam of dsRNA viral ancestors and traits from dsDNA and single-stranded RNA (ssRNA) viruses.IMPORTANCE Structural analyses highlight the constraint of virus evolution to a limited number of capsid protein folds and assembly strategies that result in a functional virion. We report the cryo-EM and cryo-electron tomography structures and the results of atomic force microscopy studies of the infectious bursal disease virus (IBDV), a double-stranded RNA virus with an icosahedral capsid. We found evidence of a new inner shell that might act as an internal scaffold during IBDV assembly. The use of an internal scaffold is reminiscent of tailed dsDNA viruses, which constitute the most successful self-replicating system on Earth. The IBDV scaffold protein is multifunctional and, after capsid maturation, is genome bound to form ribonucleoprotein complexes. IBDV encompasses numerous functional and structural characteristics of RNA and DNA viruses; we suggest that IBDV is a modern descendant of ancestral viruses and comprises different features of current viral lineages.

Newcastle Disease Virus Infection in Quail.

Newcastle disease (ND), caused by virulent strains of Newcastle disease virus (NDV), is a devastating disease of poultry worldwide. The pathogenesis of ND in quail is poorly documented. To characterize the ability of virulent NDV strains to replicate and cause disease in quail, groups of 14 two-week-old Japanese quail ( Coturnix japonica) were experimentally inoculated with 108 EID50 (embryo infectious dose 50%) units of 1 of 4 virulent NDV strains: 2 isolated from quail ( N2, N23) and 2 from chickens ( Israel, Pakistan). At day 2 postinfection, noninfected quail (contact group) were added to each infection group to assess the efficacy of virus transmission. Tested NDV strains showed moderate pathogenicity, with highest mortality being 28% for the N2 strain and below 10% for the others. Two N2-inoculated birds showed neurological signs, such as head tremor and ataxia. Microscopic lesions were present in N2-, Israel-, and Pakistan-inoculated birds and consisted of nonsuppurative encephalitis. Contact birds showed no clinical signs or lesions. In both inoculated and contact birds, virus replication was moderate to minimal, respectively, as observed by immunohistochemistry in tissues and virus isolation from oropharyngeal and cloacal swabs. Strains originally isolated from quail resulted in higher numbers of birds shedding in the inoculation group; however, transmission appeared slightly more efficient with chicken-derived isolates. This study shows that virulent NDV strains have limited replicative potential and mild to moderate disease-inducing ability in Japanese quail.

Protection of Chinese painted quails (Coturnix chinensis) against a highly pathogenic H5N1 avian influenza virus strain after vaccination.

Chinese painted quails immunized with a single dose (6 µg HA) of inactivated H5N1 (clade 1) influenza vaccine NIBRG-14 and challenged with 100 LD50 of the heterologous A/Swan/Nagybaracska/01/06(H5N1) (clade 2.2) strain were protected, whereas unvaccinated quails died after challenge. No viral antigens or RNA were detected in cloacal swabs from immunized animals. Sera obtained post-immunization gave low titres in serological assays against the vaccine and the challenge viruses. Our results demonstrate the protective efficacy of the NIBRG-14 strain against the challenge virus and the usefulness of these small birds in protection studies of influenza vaccines.

Novel picornavirus in domesticated common quail (Coturnix coturnix) in Hungary.

This study reports the detection of a novel picornavirus in domesticated common quail (Coturnix coturnix) in Hungary. The 8159-nucleotide (nt)-long RNA genome of this virus, named quail picornavirus (QPV1-HUN/2010; JN674502), shows only 43%, 39% and 47% amino acid (aa) identity in the P1 (857 aa), P2 (458 aa) and P3 (777 aa) coding regions respectively, to the closest reference, avian sapelovirus. The 5'UTR contains a variant type IV IRES with a 20-nt-long apical "8"-like structure that is conserved in avian-origin and seal picornaviruses. The 390-aa-long L protein is cysteine rich and encodes two copies of a 34-aa-long repeat motif. Quail picornavirus represents a novel picornavirus species and perhaps a novel genus.

Combined exposure of Japanese quails to cyanotoxins, Newcastle virus and lead: oxidative stress responses.

Wild birds are continually exposed to many anthropogenic and natural stressors in their habitats. Over the last decades, mass mortalities of wild birds constitute a serious problem and may possibly have more causations such as natural toxins including cyanotoxins, parasitic diseases, industrial chemicals and other anthropogenic contaminants. This study brings new knowledge on the effects of controlled exposure to multiple stressors in birds. The aim was to test the hypothesis that influence of cyanobacterial biomass, lead and antigenic load may combine to enhance the effects on birds, including modulation of antioxidative and detoxification responses. Eight treatment groups of model species Japanese quail (Coturnix coturnix japonica) were exposed to various combinations of these stressors. The parameters of detoxification and oxidative stress were studied in liver and heart after 30 days of exposure. The antioxidative enzymatic defense in birds seems to be activated quite efficiently, which was documented by the elevated levels and activities of antioxidative and detoxification compounds and by the low incidence of damage to lipid membranes. The greatest modulations of glutathione level and activities of glutathione-S-transferase, glutathione peroxidase, glutathione reductase, superoxide dismutase, catalase and lipid peroxidation were shown mostly in the groups with combined multiple exposures. The results indicate that the antioxidative system plays an important role in the protective response of the tissues to applied stressors and that its greater induction helps to protect the birds from more serious damage. Most significant changes of these "defense" parameters in case of multiple stressors suggest activation of this universal mechanism in situation with complex exposure and its crucial role in protection of the bird health in the environment.

Viral Metagenomic Analysis of Japanese Quail (Coturnix japonica) with Enteritis in the Republic of Korea.

We performed viral metagenomics analysis of Japanese quail affected with enteritis to elucidate the viral etiology. Metagenomics generated 21,066,442 sequence reads via high-throughput sequencing, with a mean length of 136 nt. Enrichment in viral sequences suggested that at least three viruses were present in quail samples. Coronavirus and picornavirus were identified and are known as pathogens causing quail enteritis that match the observed morphology. Abundant reads of coronavirus from quail samples yielded four fragment sequences exhibiting six genomes of avian coronavirus. Sequence analysis showed that this quail coronavirus was related to turkey coronavirus and chicken infectious bronchitis virus. Quail picornavirus 8177 bp in size was identified and was similar to the QPV1/HUN/01 virus detected in quails without clinical symptoms in Hungary with 84.6% nucleotide and 94.6% amino acid identity. Our results are useful for understanding the genetic diversity of quail viruses. Further studies must be performed to determine whether quail coronavirus and quail picornavirus are pathogens of the digestive tract of quails.

Artículo regular­Análisis metagenómico viral de la codorniz japonesa (Coturnix japonica) con enteritis en la República de Corea. Se realizó un análisis de metagenómica viral de codornices japonesas afectadas con enteritis para dilucidar la etiología viral. La metagenómica generó 21,066,442 lecturas de secuencia mediante secuenciación de alto rendimiento, con una longitud media de 136 nucleótidos. El enriquecimiento en secuencias virales sugirió que al menos tres virus estaban presentes en las muestras de codorniz. Se identificaron coronavirus y picornavirus que son conocidos como patógenos que causan enteritis de codornices que coinciden con la morfología observada. Las lecturas abundantes de coronavirus de muestras de codorniz produjeron cuatro secuencias de fragmentos que exhibían seis genomas de coronavirus aviar. El análisis de secuencia mostró que este coronavirus de codorniz estaba relacionado con el coronavirus del pavo y con el virus de la bronquitis infecciosa del pollo. Se identificó un picornavirus de codorniz de 8177 pares de bases de tamaño y fue similar al virus QPV1/HUN/01 detectado en codornices sin signos clínicos en Hungría con 84.6% de nucleótidos y 94.6% de identidad de aminoácidos. Estos resultados son útiles para comprender la diversidad genética de los virus de la codorniz. Se deben realizar más estudios para determinar si el coronavirus y el picornavirus de las codornices son patógenos del tracto digestivo de las codornices.

Role of Marek's disease herpesvirus in the induction of tumours in Japanese quail (Coturnix coturnix japonica) by methylcholanthrene.

The QT35 cell line, established from 20-methylcholanthrene (MCA)-induced tumours in Japanese quail, is positive for Marek's disease virus (MDV), and therefore we examined whether MDV is important for the development of MCA-induced tumours. Japanese quail were inoculated with the JM16 strain of MDV at 1 or 3 days of age or left uninoculated. At 3 weeks of age, quail were injected in the breast muscle with 4 mg MCA in corn oil or corn oil alone. Quail were observed for tumours three times/week and at post mortem at 11 to 12 weeks of age. MDV DNA was detected by polymerase chain reaction (PCR) in spleens of 14/20 birds inoculated with JM16+corn oil and of 53/71 birds inoculated with JM16+MCA. Interestingly, 1/74 quail was positive in the MCA group alone for MDV DNA. Tumours were collected for histopathology, cell line development, and PCR and reverse transcriptase-PCR for the presence of MDV. Tumours developed in 38/83 MCA-treated and 32/85 JM16+MCA-treated quail. Fibrosarcomas without metastasis were the only tumours observed in the MCA-treated quail, while quail treated with JM16 and MCA developed undifferentiated tumours, fibrosarcomas, lymphosarcomas or combinations with or without metastasis. One out of 20 quail receiving JM16 alone developed a lymphosarcoma. Cell line development was not influenced by JM16. Tumours from MCA-treated quail were negative for MDV, while 19/29 were positive in the JM16+MCA group. MDV transcripts were present in 13/18 tumours examined in the JM16+MCA group. In conclusion, MDV did not affect tumour development but did influence tumour aggression and histological type.

Pathogenicity of a quail (Coturnix coturnix japonica)-derived Marek's disease virus rescued from the QT35 cell line.

The QT35 cell line was established in 1977 from methylcholanthrene-induced tumors in Japanese quail. It was later shown that at least some of the QT35 cell lines were latently infected with Marek's disease (MD) virus (MDV). An MDV-like herpesvirus, named quail MDV (QMDV), was isolated from QT35 cells in 2000 by Yamaguchi et al. To determine the pathogenicity of QMDV, we inoculated 10-day-old specific-pathogen-free chickens with QMDV JM (virulent), RB-1B (very virulent), or 584A (very virulent plus). In addition, we inoculated 5-day-old Japanese quail with QMDV, JM, or RB-1B. QMDV is pathogenic in chickens with a tumor incidence comparable to JM. QMDV also caused MD in three out of 18 infected Japanese quail. In conclusion, QMDV is a virulent MDV, and its presence in QT35 cells has implications for the use of QT35 cells for vaccine production.

Effect of omega-3 rich diet on the response of Japanese quails (Coturnix coturnix japonica) infected with Newcastle disease virus or avian influenza virus H9N2.

This study was performed to evaluate the effects of omega-3 supplementation on growth performance, clinical signs, post-mortem lesions, haemagglutination inhibition (HI) antibody titres, gene expression and histopathology in quails (Coturnix coturnix japonica) infected with Newcastle disease virus (NDV) and avian influenza virus (AIV) H9N2. One hundred, 40-day-old male quails were divided into 5 groups: G1, fed a control basal diet; G2A, infected with NDV; G2B, infected with H9N2; G3A, infected with NDV and given omega-3, and G3B, infected with H9N2 and given omega-3. The dietary omega-3 supplementation was continued for 4 weeks: two weeks before infection and two weeks after intranasal infection with virulent NDV and AIV H9N2. Our results revealed significant differences (P < 0.05) in growth performance, HI antibody titres, clinical signs, post-mortem lesions, mortality, viral shedding rates, immunological parameters, and histopathological lesions between the treated (G3A and G3B) and untreated (G2A and G2B) groups. In conclusion, dietary omega-3 supplementation for 4 weeks can improve growth performance and alleviate the deleterious immunological and pathological effects of NDV and AIV H9N2 infection in quails.

Immunosenescence and age-related susceptibility to influenza virus in Japanese quail.

We evaluated juvenile, pubescent, reproductive adult, and aged Japanese quail (Coturnix coturnix japonica) to determine if there were age-related differences in immune function with the hypothesis that aged birds would have weaker immune responses. Immune responses were measured using phytohemagglutinin (PHA) skin test, antibody response to foreign red blood cells and exposure to an H9N2 influenza virus. Adult birds consistently had stronger immune responses than young and aged birds. Aged quail had skin responses 38% lower than adults. Pubescent birds' mean anti-red blood cell response was four-fold lower than adult birds. Adults had greater increase in total anti-viral antibody between primary and secondary infections than all other groups. Our data demonstrate an age-related difference in immune function in Japanese quail that has similarities to age-related immunity in humans; younger and older animals had weaker immune responses compared to young adults.

Pathobiology of H9N2 avian influenza virus in Japanese quail (Coturnix coturnix japonica).

Clinical signs, serologic response, viral contents of the trachea and intestine, and histopathological and ultrastructural changes of the tracheal epithelium of Japanese quail experimentally infected with field isolate of H9N2 avian influenza were studied. Vaccinated and unvaccinated quail were inoculated with 10(6.3) 50% embryo infectious dose/bird of A/ chicken/Iran/SH-110/99 (H9N2) virus via nasal inoculation. Clinical signs such as depression, ruffled feathers, diarrhea, and nasal and eye discharges were observed 6 days postinfection (PI). No mortality was observed; however, there was reduction in feed and water consumption and egg production. However, the serologic response of vaccinated challenged and unvaccinated challenged birds was not significantly different. Unvaccinated challenged quail showed more severe histopathologic reaction in their lungs and trachea. Hyperemia, edema, infiltration of inflammatory cells, and deciliation and sloughing of the tracheal epithelium were observed. Ultrastructural study showed dilatation of endoplasmic reticulum and degeneration of Golgi apparatus and cilia of the tracheal lining cells of respiratory epithelium.

Adaptation of influenza A/Mallard/Potsdam/178-4/83 H2N2 virus in Japanese quail leads to infection and transmission in chickens.

To assess the potential of quail as an intermediate host of avian influenza, we tested the influenza A/Mallard/ Potsdam/178-4/83 (H2N2) virus to determine whether through adaptation a mallard strain can replicate and transmit in quail, as well as other terrestrial birds. After five serial passages of lung homogenate a virus arose that replicated and transmitted directly to contact cage mates. To test whether adaptation in quail led to interspecies transmission, white leghorn chickens were infected with the wild-type (mall/178) and quail-adapted (qa-mall/178) viruses. The results show that mall/178 H2N2 does not establish an infection in chickens nor does it transmit, while qa-mall/178 H2N2 infects and transmits to contact chickens causing clinical signs like depression and diarrhea. Completed sequences indicate six amino acid changes spanning four genes, PB2, PB1, HA, and NP, suggesting that the internal genes play a role in host adaptation. Further adaptation of qa-mall/178 in white leghorn chickens created a virus that replicated more efficiently in the upper and lower respiratory tract. Sequence analysis of the chicken-adapted virus points to a deletion in the neuraminidase stalk region.

Pathology and Tissue Distribution of an LPAI H5N8 of North American Lineage Isolated from an Outbreak in Commercial Japanese Quail (Coturnix c. japonica) in the Central Valley of California.

This report describes the pathology and tissue distribution of avian influenza (AI) antigens by immunohistochemistry (IHC) in the tissues of commercial layer quail from a natural outbreak of low pathogenic avian influenza (LPAI) H5N8. LPAI virus H5N8 of North American lineage was diagnosed in commercial Japanese quail hens ( Coturnix coturnix japonica) in California based on serology, reverse-transcriptase real-time polymerase chain reaction, virus isolation, and sequencing. The sudden increase in mortality in a flock of laying quail hens had prompted the submission of 15 live and 5 dead, 10- to 15-wk-old quail to the California Animal Health and Food Safety Laboratory System, Turlock branch in the beginning of April 2014. There was mild bilateral swelling of the eyelids and greenish diarrhea in 4/15 live quail submitted. On postmortem examination, there were severe, extensive hemorrhages and multifocal, confluent pale foci in the pancreas in 10/20 birds. Liver gross lesions in five birds ranged from a few pale areas to numerous disseminated foci. Histology revealed moderate to severe necrosis of acinar cells in the pancreas with little or no inflammation in most of the birds. Livers had acute multifocal coagulative necrosis of hepatocytes with fibrin exudation and infiltration of few to large numbers of heterophils and lymphocytes randomly scattered throughout. The AI virus was detected in the nucleus and cytoplasm of pancreatic acinar cells and hepatocytes by IHC targeting the nucleoprotein of the AI virus. A few birds had AI antigen in the reticuloendothelial cells of the spleen, endothelial cells of the lungs, epithelium of the respiratory mucosa, and lamina propria of the intestine. The severity of the lesions observed in this natural outbreak of LPAI in quail was higher than that expected for the pathotypic presentation in this species.

Novel 5'/3'RACE Method for Amplification and Determination of Single-Stranded RNAs Through Double-Stranded RNA (dsRNA) Intermediates.

To acquire the full-length sequences and to determine the 5'/3'ends of the RNA genomes and mRNA transcripts using the rapid amplification of cDNA ends (RACE) protocols-via cDNA or mRNA templates-are a great challenge. This 4-steps RNA-based RACE method uses different ways to determine the RNA ends through a double-stranded (ds) RNA intermediate (dsRNA-RACE). In the first step a complementary RNA strand is synthesised by Phi6 RNA replicase enzyme next to the template ssRNA forming a dsRNA intermediate. The following steps include adapter ligation, nucleic acid purification and two classical methods with minor modifications reverse transcription and polymerase chain reaction. The dsRNA-RACE protocol could be used in wide variety of ssRNA (cellular, viral, bacterial, etc.) templates in the field of microbiology and cellular biology and suitable for the amplification of full-length RNAs including the 5'/3'ends. This is a novel, expansively utilizable molecular tool with fewer disadvantages than the existing 5'/3'RACE approaches.

Activation of homologous complement via the alternative complement pathway by quail cells transformed by Rous sarcoma virus.

After incubation of the cells with fresh quail serum, deposition of the third component of complement (C3) was demonstrated on the cell surface of various quail cell lines transformed by Rous sarcoma virus (RSV) as well as on that of primary quail embryo (QE) cells transformed by RSV. The C3 deposition occurred irrespective of virus production. On the other hand, the C-3 deposition was not observed on two quail cell lines transformed by a chemical carcinogen, QE cells infected with avian leukosis virus or normal QE cells. Moreover, QE cells infected with a temperature-sensitive mutant of RSV activated the complement at 37 degrees C but not at 41 degrees C. Since the progeny virus was generated even at 41 degrees C, viral molecules on the cell surface may not play an essential role for the activation. The activation of complement was blocked by EDTA but not by EGTA-Mg++. Therefore, the complement activation on the transformed cells appears to be mediated via the alternative complement pathway (ACP). Similar results were obtained with the complement consumption test; the residual cytolytic activity of fresh quail serum via ACP was markedly reduced by pre-incubation of the serum with transformed cells.

Evaluation of Japanese quail as a model system for avian transgenesis using avian leukosis viruses.

Vertical transmission of avian leukosis viruses (ALV) can occur genetically through the germline for both male and female chickens but only nongenetically or congenitally through the female. We had previously shown that tolerantly ALV-infected males, from ALV injection into fertile chicken eggs at day of set, can transmit proviral DNA to their progeny through the germline. An attempt was made to repeat this successful retroviral germline insertion technique of chickens in Japanese quail. After an initial difficulty of infecting quail chicks in ovo at day of set with high titer nonpathogenic recombinant and pathogenic ALV, adequate numbers of tolerantly ALV-infected quail were produced by injecting ALV-infected chicken embryo fibroblasts (CEF) at day of set. Tolerantly ALV-infected male and female quail were then mated to nonviremic quail and vertical transmission of ALV to progeny chicks was determined by analyzing blood for viral antigens and proviral DNA using standard techniques. Vertical transmission of ALV was only detected in the progeny of viremic females. Thus, little or no germline transmission of ALV to progeny occurred from viremic males. Tolerantly ALV-infected males and females from congenital ALV infection, which should infect the embryo and presumably the primordial germ cells (PGC) earlier than egg injection, were mated to nonviremic quails. Vertical transmission of ALV to progeny chicks was analyzed as before. Again, vertical transmission of ALV was only detected in the progeny of viremic females. We conclude that Japanese quail will not be useful in avian transgenic studies involving ALV retroviral vectors.

Acquisition of pathogenicity of a Newcastle disease virus isolated from a Japanese quail by intracerebral passage in chickens.

Newcastle disease virus (NDV) was isolated from a Japanese quail (Cotornix cotornix japonica). The effect of intracerebral and intranasal passages of the NDV in chickens on the pathogenicity was studied. Pathogenicity of the viruses of different passage levels was compared with that of the original isolate by the mean death time with the minimum lethal dose in chicken embryos, intracerebral pathogenicity index in day-old chicks, intravenous pathogenicity index with 6-week-old chickens and the mortality rates of chickens and quails inoculated intravenously or intranasally. The original isolate from the quail did not kill chickens but only embryos and some one-day-old chicks, exhibiting a mesogenic character. Pathogenicity of the virus of the 10th intranasal passage was not different from that of the original isolate. The viruses passaged intracerebrally, on the other hand, killed chickens of all ages by either route of inoculation, showing a velogenic property. Virus recovery from the blood and the brain was positive only in the chickens infected with brain-passaged viruses by any route of inoculation. Virus titers in the tissues of chickens infected with the brain-passaged viruses were higher than those with the original isolate and the virus of the 10th intranasal passage. These results indicate that the enhanced pathogenicity of the mesogenic NDV isolate from the quail for chickens was induced by acquiring the properties of neurotropism and pantropism through intracerebral passage in chickens.

Susceptibility and intra-species transmission of the H9N2 G1 prototype lineage virus in Japanese quail and turkeys.

Avian influenza viruses of the H9N2 subtype have circulated in the poultry population in Asia, Far and Middle East since the mid-1990 s. One of the most widespread lineages established in poultry is the G1 lineage. This lineage has undergone further evolution and reassortment since its first detection in 1997 and G1-like H9N2 viruses still circulate. In this study we have investigated the susceptibility of quail and turkeys to the H9N2 G1-lineage prototype strain (A/quail/Hong Kong/G1/97). Contact transmission experiments were carried out in both avian species. Animals were infected oro-nasally with increasing doses of the virus (10(3)-10(6) EID 50/0.1 ml) and sentinel birds were introduced 4 days post infection (pi) in each experimental group. Quail were more susceptible than turkeys, as they were readily infected with lower challenge doses. Interestingly, infection of turkeys was associated with worse clinical condition. Transmission was detected in both species. Quail infected with a dose less than or equal to 10(4) EID50 transmitted the virus to the sentinels without showing any signs of disease. These findings reinforce the hypothesis that quail may ensure the perpetuation of H9N2 viruses in poultry, acting as a silent reservoir.

Celulite em codornas japonesas alimentadas com extrato de orégano nas dietas e inoculadas com Escherichia coli / Cellulitis in Japanese quails fed oregano extract in the diet and inoculated with Escherichia coli

Com o objetivo de avaliar a utilização do extrato de orégano nas dietas de codornas japonesas (Coturnix coturnix japonica) e desafiadas com cepas de Escherichia coli, sobre as características de desempenho, a incidência de celulite aviária e titulação de anticorpos específicos contra antígenos de E. coli, foram utilizadas 360 codornas japonesas, com 90 dias de idade, distribuídas em gaiolas de arame galvanizado em galpão convencional. O delineamento experimental foi inteiramente casualizado, em esquema fatorial 5x2 (extrato de orégano x desafiado ou não com E. oli), totalizando dez tratamentos com seis repetições de seis aves por gaiola. Os níveis do extrato de orégano (EO) avaliados foram: 0,00; 0,025; 0,050; 0,100 e 0,150%. Foram avaliadas características de desempenho produtivo, lesões macroscópicas da celulite após períodos pós-inoculação das cepas e amostras de soro foram colhidas para verificar a titulação de anticorpos nas aves. Os dados obtidos foram submetidos à análise de variância e as médias comparadas pelo Teste T. Foi observado efeito de E. coli sobre todas as características produtivas, independentemente dos níveis de EO avaliados, onde grupos desafiados apresentaram piores resultados de desempenho. As lesões macroscópicas, características da celulite, observadas somente nas aves desafiadas com E. coli foram classificadas como grau leve e sem presença de hemorragias. Para a titulação de anticorpos específicos, houve maior quantificação para aves desafiadas com as cepas de E. coli em relação às não desafiadas. Pode-se concluir que o extrato de orégano suplementado nas rações não se mostrou eficaz frente ao desafio com E. coli em codornas na fase de postura e as aves desafiadas com E. coli apresentaram maiores respostas imunes humoral e celular, em relação às não desafiadas, caracterizadas pelo aumento na titulação de anticorpos e pela lesão macroscópica peitoral, independentemente dos níveis de extrato de orégano avaliados.(AU)

The aim was to evaluate the use of oregano extract in Japanese quail (Coturnix coturnix japonica) diet, challenged with Escherichia coli strains, on performance, incidence of avian cellulitis and of antibody specific antigens against E. coli. Three hundred sixty Japanese quails with 90 days of age were distributed into galvanized wire cages in a conventional shed. The experimental design was completely randomized in factorial 5x2 design (oregano extract x challenged or not with E. coli), totaling ten treatments with six replicates of six birds per cage. Oregano extract levels were 0.00, 0.025, 0.050, 0.100 and 0.150%. Performance productive characteristics were evaluated, macroscopic lesions of cellulitis were measured after post-inoculation of the strains, and serum samples were collected for antibodies during experiment. The data were subjected to analysis of variance and averages compared by T test. Effect of E. coli was observed on all productive characteristics, regardless of the EO level evaluated, where challenged groups showed worse performance results. The macroscopic lesions, characteristic of cellulitis, observed only in birds of groups challenged with E. coli, were classified as mild and without bleeding. For specific antibodies, there was a higher number of birds challenged with E. coli strains in relation to unchallenged birds. It can be concluded that oregano extract supplemented in the diet was not effective against the challenge with E. coli in laying quails, and challenged birds with E. coli showed higher humoral and cellular immune response, compared with unchallenged birds, characterized by increased antibody titer and pectoral macroscopic lesion, regardless of the oregano extract levels evaluated.(AU)