RESUMO
This study assesses different IBV vaccination regimens in broiler chickens using commercially available live attenuated GI-23 (Egyptian-VAR2) and GI-1 (H120) vaccines. Vaccines were administered at 1, 14 days of age, or both. The ciliostasis test, following wild-type VAR2 challenge at 28 days of age, indicated that classic H120+VAR2 at one day old followed by the VAR2 vaccine at 14 days of age provided the highest level of protection (89.58%). Similarly, administering VAR2 at 1 day of age and classic H120 at 14 days of age demonstrated substantial protection (85.42%). Conversely, administering only classic H120 and VAR2 at one day old resulted in the lowest protection level (54.17%). Tracheal virus shedding quantification and assessment of trachea and kidney degenerative changes were significantly lower in vaccinated groups compared to the unvaccinated-challenged group. In conclusion, a carefully planned vaccination regimen based on homologous vaccination offers the most effective clinical protection in broiler chickens.
Assuntos
Galinhas , Infecções por Coronavirus , Vírus da Bronquite Infecciosa , Doenças das Aves Domésticas , Vacinas Atenuadas , Vacinas Virais , Animais , Vírus da Bronquite Infecciosa/imunologia , Vírus da Bronquite Infecciosa/genética , Galinhas/virologia , Doenças das Aves Domésticas/prevenção & controle , Doenças das Aves Domésticas/virologia , Doenças das Aves Domésticas/imunologia , Infecções por Coronavirus/veterinária , Infecções por Coronavirus/prevenção & controle , Infecções por Coronavirus/virologia , Infecções por Coronavirus/imunologia , Vacinas Virais/imunologia , Vacinas Virais/administração & dosagem , Vacinas Atenuadas/imunologia , Vacinas Atenuadas/administração & dosagem , Vacinação/veterinária , Eliminação de Partículas Virais , Traqueia/virologia , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Eficácia de VacinasRESUMO
This study evaluated the efficacy of live and inactivated conventional GII LaSota and recombinant GVII Newcastle disease vaccines in commercial broilers. The experimental groups (G2-G7) were vaccinated on day 7 and day 21 of age with live vaccines from the same vaccine type "GII LaSota, GVII vaccine (A), GVII vaccine (B)" via eye drop; however, G3, G5, and G7 received a single dose from inactivated counterpart vaccines subcutaneously on day 7 of age. Vaccine efficacy was evaluated based on elicited humoral immunity, clinical protection, and reduction in virus shedding after challenge with virulent GVII 1.1. strain. Results demonstrated that live and inactivated recombinant GVII vaccine based on VG/GA strain backbone elicited superior protection parameters (100% protection). Although the conventional GII LaSota live and inactivated vaccination regime protected 93.3% of vaccinated birds, the virus shedding continued until 10 DPC. The post-vaccination serological monitoring was consistent with protection results. The study concludes that conventional GII ND vaccines alone are probably insufficient due to the current epidemiology of the GVII 1.1 NDV strains. Our findings further support that protection induced by recombinant GVII 1.1. ND vaccines are superior. Interestingly, the efficacy of recombinant ND vaccines seemed to be influenced by the backbone virus since the VG/GA backbone-based vaccine provided better protection and reduced virus shedding.
RESUMO
In this study, the protective efficacy of an E. coli live attenuated vaccine was compared to the preventive administration of lectin preparation before the challenge. Two hundred broiler chicks were divided into eight equal groups. The first group was used as a negative control group. Three groups were vaccinated at day 1 with the avian colibacillosis live vaccine of which one group served as a vaccinated nonchallenged group. Another two groups were treated with lectin product (0.5 mL/L drinking water) for three days before the challenge. The last two groups served as challenge control for either E. coli O78 or O125 strains. The challenge was conducted at three weeks of age with either homologous O78 or heterologous O125 E. coli strains, using 0.5 mL/bird of each avian pathogenic E. coli (APEC) strain (~108 colony forming units "CFU"/mL)/subcutaneously. The bodyweight and feed conversion ratios (FCR) were calculated for four weeks. Clinical signs and gross and histopathological lesions were scored at two and seven days post inoculation (dpi). The heart and liver of euthanized chickens at 2 dpi were removed aseptically and homogenized to evaluate pathogenic E. coli colonization. Results showed that live avian colibacillosis vaccine reduced mortalities and APEC colonization in the homologous challenge group but not in the heterologous challenge group. Lectin-treated groups showed 20% and 16% mortality after challenge with E. coli O78 and O125, respectively, and both groups showed performance parameters, clinical signs, and histopathological lesion scores comparable to the negative control group, with variable E. coli colonization of heart and liver. The study demonstrated the efficacy of live attenuated avian colibacillosis vaccine against homologous but not heterologous APEC challenge in broiler chickens. The lectin-containing products can be used as a preventive medication to reduce the clinical impacts of colibacillosis regardless of the challenge strain. Standardization of the evaluation parameters for APEC vaccines is recommended.
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The author name Salama Abohamra in the original published version of this article should have been Salama Abohamra Sayed Shany.
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In this study, commercial broilers were experimentally infected with single (classical IBV, variant IBV or AIV-H9N2) or mixed AIV-H9N2 with classical, variant or vaccine strains of IBV. Birds were monitored for clinical and pathological outcomes and virus shedding for 10days post infection (DPI). Clinical signs were limited to the respiratory tract in all challenged groups and varied from mild to moderate mouth breathing to severe respiratory signs with snorting sound and extended head. Mortalities were only recorded in mixed AIV-H9N2/variant IBV challenge group. AIV-H9N2 challenge caused tracheal petechial hemorrhage that progressed to tracheal congestion and caseation. In mixed AIV-H9N2/IBV vaccine challenge, severe tracheitis with bronchial cast formation was observed. In mixed AIV-H9N2/variant IBV challenge severe congestion of the tracheal mucosa and excessive exudates with a tendency to form tubular casts were observed. Kidney ureate deposition was only observed in variant IBV challenge group. Histopathologically, tracheal congestion, severe degeneration, and deciliation were noticed in all groups of mixed infection. Interestingly, hemorrhage and atrophy were observed in thymus gland of birds challenged with single AIV-H9N2 or mixed AIV-H9N2/IBV. There was no difference in the tracheal shedding level of variant IBV between single and mixed infected groups while classical IBV shedding increased in mixed infection group. Interestingly, the AIV-H9N2 showed constantly high shedding titers till 7DPI with variant or vaccine IBV co-infection. In conclusion, co-infection of IBV and AIV-H9N2 induced severe clinical outcome and high mortality. Also, IBV co-infection increased the shedding of AIV-H9N2 in experimentally infected birds.
Assuntos
Galinhas , Coinfecção/veterinária , Infecções por Coronavirus/veterinária , Influenza Aviária/virologia , Doenças das Aves Domésticas/virologia , Animais , Coinfecção/virologia , Infecções por Coronavirus/virologia , Vírus da Bronquite Infecciosa/fisiologia , Vírus da Influenza A Subtipo H9N2/fisiologia , Eliminação de Partículas ViraisRESUMO
The early detection of Eimeria stiedae in the hepatic tissue of experimentally infected rabbits was investigated using molecular assay. Forty 6-week-old male New Zealand rabbits were divided into two groups. Group A (30 animals) was infected with 2.5 × 10(4) sporulated oocysts of E. stiedae per animal on Day 0 and Group B (10 animals) was used as the uninfected controls. Three animals from Group A and one from Group B were sacrificed at 0, 3, 6, 9, 12, 15, 18, 21, 24 and 27 days post infection (PI). Gross and microscopic post-mortem findings were recorded. Polymerase chain reaction (PCR) of the E. stiedae internal transcribed spacer 1 genomic region was conducted on blood, liver tissue, and feces from the Group A experimentally infected animals. Macroscopically, the liver showed irregular yellowish white nodules pathognomonic to E. stiedae infection beginning on Day 15 PI. Hepatomegaly and ascites were obvious from Day 21-24 PI. The presence of different E. stiedae schizonts and gametocytes in the histopathological sections of the biliary epithelium were evident on Day 15 PI. The E. stiedae PCR was first positive in liver tissues on Day 12 and in fecal samples on Day 18 PI, but the blood samples were negative. In conclusion, the PCR can be used for early diagnosis and control of E. stiedae schizonts before shedding of the oocysts in feces.
Assuntos
Coccidiose/veterinária , Eimeria/isolamento & purificação , Hepatopatias Parasitárias/veterinária , Fígado/parasitologia , Coelhos/parasitologia , Animais , Ascite/veterinária , Ductos Biliares/patologia , Coccidiose/diagnóstico , Coccidiose/parasitologia , DNA Intergênico/análise , DNA Intergênico/sangue , DNA de Protozoário/sangue , DNA de Protozoário/isolamento & purificação , Diagnóstico Precoce , Eimeria/genética , Fezes/parasitologia , Hepatomegalia/veterinária , Hiperplasia/veterinária , Fígado/patologia , Hepatopatias Parasitárias/diagnóstico , Hepatopatias Parasitárias/parasitologia , Masculino , Reação em Cadeia da Polimerase/veterinária , Sensibilidade e EspecificidadeRESUMO
In this study, respiratory viral pathogens were screened using real-time RT-PCR in 86 broiler chicken flocks suffering from respiratory diseases problems in 4 Egyptian governorates between January 2012 and February 2014. The mortality rates in the investigated flocks ranged from 1 to 47%. Results showed that mixed infection represented 66.3% of the examined flocks. Mixed infectious bronchitis (IBV) and avian influenza (AI)-H9N2 viruses were the most common infection (41.7%). Lack of AI-H9N2 vaccination and high rates of mixed infections in which AI-H9N2 is involved indicate an early AI-H9N2 infection with a potential immunosuppressive effect that predisposes for other viral infections. High pathogenic AI-H5N1 and virulent Newcastle disease virus (vNDV) infections were also detected (26.7% and 8.1%, respectively). Interestingly, co-infection of AI-H9N2 with either AIV-H5N1 or vNDV rarely resulted in high mortality. Partial cell-mediated immunity against similar internal AI genes, as well as virus interference between AI and vNDV, could be an explanation for this. Highly prevalent IBV and AI-H9N2 were isolated and were molecularly characterized based on S1 gene hypervariable region 3 ( HVR3: ) and hemagglutinin gene (HA) sequences, respectively. IBV strains were related to the variant group of IBV with multiple mutations in HVR3. Though AI-H9N2 viruses showed low rate of evolution in comparison to recent strains, few amino acid substitutions indicative of antibody selection pressure were observed in the HA gene. In conclusion, mixed viral infections, especially with IBV and AI-H9N2 viruses, are the predominant etiology of respiratory disease problems in broiler chickens in Egypt. Further investigations of the role of AI, IBV, and ND viruses' co-infections and interference in terms of altering the severity of clinical signs and lesions and/or generating novel reassortants within each virus are needed.
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Galinhas , Infecções por Coronavirus/veterinária , Influenza Aviária/epidemiologia , Doença de Newcastle/epidemiologia , Doenças das Aves Domésticas/epidemiologia , Sequência de Aminoácidos , Animais , Coinfecção/epidemiologia , Coinfecção/mortalidade , Coinfecção/veterinária , Coinfecção/virologia , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/mortalidade , Infecções por Coronavirus/virologia , Egito/epidemiologia , Vírus da Bronquite Infecciosa/genética , Vírus da Bronquite Infecciosa/fisiologia , Virus da Influenza A Subtipo H5N1/genética , Virus da Influenza A Subtipo H5N1/fisiologia , Vírus da Influenza A Subtipo H9N2/genética , Vírus da Influenza A Subtipo H9N2/fisiologia , Influenza Aviária/mortalidade , Influenza Aviária/virologia , Doença de Newcastle/mortalidade , Doença de Newcastle/virologia , Vírus da Doença de Newcastle/genética , Vírus da Doença de Newcastle/fisiologia , Filogenia , Reação em Cadeia da Polimerase/veterinária , Doenças das Aves Domésticas/mortalidade , Doenças das Aves Domésticas/virologia , Prevalência , Proteínas Virais/genéticaRESUMO
Whereas H5N1 vaccine and several H5N2 vaccines are commercially available and are used to control H5N1 outbreaks in some endemic countries, infections hit many vaccinated flocks. The following study was conducted to compare the efficacy of such vaccines and to assess their potential induction of antibodies against the haemagglutinin of local H5N1 isolate after single vaccination. The possible beneficiary effect of booster dose at different intervals was screened for both H5N1 vaccine as well as a selected H5N2 candidate. Differences in the serological immune response among native and cross breeds were also screened. No significant variations were detected between available commercial H5N1 and H5N2 vaccines after single vaccination. Two vaccination shots using H5N1 but not H5N2 vaccine were found to be superior to a single vaccination scheme, where chicks developed more conceivable antibody titers than in single vaccination program. There was considerable variation among chicken lines in the immune response to H5N1 vaccine: native breeds possessed the highest antibody titers as compared to other breeds.
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Anticorpos Antivirais/sangue , Imunidade Humoral/imunologia , Vacinas contra Influenza/imunologia , Influenza Aviária/imunologia , Vacinação/veterinária , Animais , Galinhas , Virus da Influenza A Subtipo H5N1/imunologia , Vírus da Influenza A Subtipo H5N2/imunologia , Vacinas contra Influenza/administração & dosagemRESUMO
BACKGROUND: The highly pathogenic H5N1 is a major avian pathogen that crosses species barriers and seriously affects humans as well as some mammals. It mutates in an intensified manner and is considered a potential candidate for the possible next pandemic with all the catastrophic consequences. METHODS: Nasal swabs were collected from donkeys suffered from respiratory distress. The virus was isolated from the pooled nasal swabs in specific pathogen free embryonated chicken eggs (SPF-ECE). Reverse transcriptase polymerase chain reaction (RT-PCR) and sequencing of both haemagglutingin and neuraminidase were performed. H5 seroconversion was screened using haemagglutination inhibition (HI) assay on 105 donkey serum samples. RESULTS: We demonstrated that H5N1 jumped from poultry to another mammalian host; donkeys. Phylogenetic analysis showed that the virus clustered within the lineage of H5N1 from Egypt, closely related to 2009 isolates. It harboured few genetic changes compared to the closely related viruses from avian and humans. The neuraminidase lacks oseltamivir resistant mutations. Interestingly, HI screening for antibodies to H5 haemagglutinins in donkeys revealed high exposure rate. CONCLUSIONS: These findings extend the host range of the H5N1 influenza virus, possess implications for influenza virus epidemiology and highlight the need for the systematic surveillance of H5N1 in animals in the vicinity of backyard poultry units especially in endemic areas.
Assuntos
Equidae/virologia , Virus da Influenza A Subtipo H5N1/genética , Virus da Influenza A Subtipo H5N1/isolamento & purificação , Infecções por Orthomyxoviridae/veterinária , Sequência de Aminoácidos , Animais , Anticorpos Antivirais/sangue , Sequência de Bases , Egito/epidemiologia , Genes Virais , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Humanos , Virus da Influenza A Subtipo H5N1/classificação , Virus da Influenza A Subtipo H5N1/patogenicidade , Epidemiologia Molecular , Dados de Sequência Molecular , Neuraminidase/genética , Infecções por Orthomyxoviridae/epidemiologia , Infecções por Orthomyxoviridae/transmissão , Infecções por Orthomyxoviridae/virologia , Filogenia , Aves Domésticas/virologia , RNA Viral/genética , Infecções Respiratórias/epidemiologia , Infecções Respiratórias/transmissão , Infecções Respiratórias/veterinária , Infecções Respiratórias/virologia , Homologia de Sequência de Aminoácidos , Especificidade da EspécieRESUMO
The sequences encoding the haemagglutinin (HA) of twelve H5N1 isolates obtained in 2006 and 2007 from different avian species in backyard holdings and poultry farms in Egypt revealed amino acid variations across the polypeptide and also in the polybasic cleavage motif of three of the isolates from backyard poultry with one, so far, unique mutation in an isolate from a chicken. The HAs of two isolates (A/goose/Egypt/R4/2007, A/chicken/Egypt/R3/2007) collected on the same day in the same village from two neighbouring houses were found to differ from each other. Five out of the seven nucleotide exchanges in these two isolates were translationally silent, and two resulted in amino acid substitutions: one in the polybasic cleavage motif and the other in the signal peptide. Circulation of different H5N1 strains possessing considerable variations in backyard poultry, particularly domestic waterfowl, draws attention to the evolution of H5N1 subtypes in Egypt.