[Evaluation of the timing of the Escherichia coli co-infection on pathogenecity of H9N2 avian influenza virus in broiler chickens]

Bacterial co-infections can probably influence the pathogenicity of H9N2 low pathogenic avian influenza virus [AIV]. This study aimed to evaluate the effect of exposure time to Escherichia coli [O:2] on the pathogenicity of H9N2 AIV in broiler chickens. Three hundred and sixty broiler chickens were randomly allocated to six equal groups. At the age of 26 days, all chicks except groups 5 and 6 were inoculated intra-nasally with H9N2 virus. At the same time, the birds in groups 1 and 5 were infected with E. coli via spray route. Birds in groups 3 and 2 were infected with E. coli three days prior to and three days post AI challenge, respectively. Mortality rates, clinical signs, gross and microscopic lesions, excretion and duration of virus shedding in faecal and tracheal samples and seroconversion to H9N2 virus were assessed in the challenged groups. The highest mortality rate was observed in chickens inoculated with H9N2 followed by E. coli. The most severe clinical signs, gross lesions, mortality rate and virus detection were observed at day 6 post challenge [PC] in birds of group 2, while the duration of virus shedding was longer in group 3 [E. coli followed by H9N2] than other groups. In conclusion, E. coli infection prior to, after or concurrently with H9N2 virus infection could exacerbate the adverse effects of the virus. Our results indicate that E. coli and H9N2 together can mutually exacerbate the condition of either disease in broiler chicks as compared to single infected birds

[Efficacy of thermostable I-2 Newcastle disease vaccine compared to B1 commercial vaccine in broiler chicken]

Frequent vaccination failures have occurred in the broiler farms in Eurasian countries during Newcastle disease outbreaks. The disease is enzootic in many countries of the region, especially in southwest Asia. I-2 vaccine has been used successfully in village chickens in many Asian and African countries. Our preliminary study showed good efficacy of the vaccine in broiler chickens. Therefore the current experimental study was conducted to compare viral shedding period of heat resistance I-2 vaccine with B1 commercial vaccine following challenge with Herts'33. For this purpose three hundred commercial broilers were randomly allocated into four groups; 1] Thermostable I-2 vaccine, 2] Hitchner B1 vaccine, 3] Challenge group with no vaccine, and 4] Negative control group. Experimental chicks were vaccinated on days 19 and 26 by the eye drop route and then the birds were challenged via intra ocular route on day 40 with a suspension containing 10[6] EID[50]/ml challenge virus. Experimental chickens were monitored by collecting buccal and cloacal swabs at different times. Collected swabs were submitted to PCR test. The results showed that vaccination can protect the birds against mortality and also decrease virus shedding; also there was not a significant difference between vaccination with I-2 and B1 vaccines

An experimental study on broiler chicken co-infected with the specimens containing avian influenza [H9 subtype] and infectious bronchitis [4/91 strain] viruses

This experimental study was carried out to induce a co-infection of H9 AIV and IBV with inoculums prepared from tracheal scrubbed epithelium tissues in natural co-infected birds to rule out the effect of field undesired environmental conditions and also other infectious causative agents. Eighty 1-day-old broilers were randomly divided into four equal groups. At 21 days of age, three test groups were inoculated intranasally with prepared inoculums containing IBV and H9 AIV alone and a co-infected group

The fourth group remained uninfected as a control group

The results showed that experimental co-infection of AIV and IBV increased the severity of clinical signs, mortality rate and gross lesions

The HI titer against AIV infection in the co-infected group was significantly higher than the HI titer of other groups, which may indicate that IBV could promote the propagation of H9N2 AIV or stimulate the immune response?

Relationship between venous blood gas parameters, thyroid hormone levels and ascites syndrome in broiler chickens exposed to cold temperature

The objective of this study was to find a relationship between blood gas parameters and thyroid hormone activity with ascites syndrome in broiler chickens exposed to cold temperature and receiving a high quality diet. One hundred and sixty one-day-old broiler chicks were randomly divided in two equal groups. To increase the incidence of ascites, chicks of group 1 were fed ad libitum with a higher condensed diet and reared under a lower ambient temperature. Weekly, blood gas parameters and thyroid hormone levels were measured and growth performance was recorded. The hearts of dead and slaughtered birds were examined for determination of arterial pressure index [API] values. Ascites incidence was clearly higher in cold-exposing chickens compared with normal rearing chickens. The mean values of carbon dioxide tension of group 1 chickens were significantly higher compared with group 2 chickens at the 4th and 5th weeks of age, while the phenomenon of oxygen was reversed in these two experimental groups. The function of thyroid hormone levels were changed at week 4 of age, as observed for blood gas parameters. In conclusion, the present study showed a significant association between thyroid hormones functions, the levels of venous blood carbon dioxide and oxygen pressures in the two groups of chickens

Effectiveness of two H9N2 low pathogenic avian influenza conventional inactivated oil emulsion vaccines on H9N2 viral replication and shedding in broiler chickens

The objective of this study was to compare the effect of two conventional H9N2 avian influenza [AI] vaccines on replication and shedding of the H9N2 AI virus in broiler chickens. These inactivated oil emulsion vaccines contain either a UAE or an Iranian H9N2 AI isolate. One hundred and fifty one-day-old commercial broiler chickens were randomly divided into six groups. The birds, except for the control group [group 4], were challenged with a low pathogenic A/Chicken/Iran/SH-110/99[H9N2] virus isolate. Birds in groups 1 and 5 were vaccinated with an Iranian AI vaccine and groups 2 and 6 with an UAE vaccine type. Birds in groups 5 and 6 were also vaccinated with an H120 strain of infectious bronchitis live vaccine. On days 3, 7, 11, and 15 post inoculations [PI] the trachea, lungs, kidneys and faeces were collected for molecular detection and quantitation of the H9N2 AI virus using TaqMan real time PCR assay. The results showed that frequency of virus recovery and viral titration was generally higher for unvaccinated challenged birds [group 3] on all days PI. No virus was detected in the chicks of group 1. The virus was detected in some cases in the tracheas and lungs of chicks in groups 2, 5 and 6. However, there was no statistically significant difference in viral replication in the trachea and lungs between chicks vaccinated with the UAE and Iranian type vaccines. The most frequent detection of the virus was in the kidneys in comparison with the other samples. The viral titer in the kidneys of unvaccinated challenged birds [group 3] on day 3, 7, 11 and 15 PI was higher than those of the same organs in the vaccinated challenged birds [groups 1, 2]. The highest titer of the virus was observed in the faeces of unvaccinated challenged and the chicks vaccinated with the IB and UAE type vaccine [group 6] on day 7 PI. There was a statistically significant difference in viral shedding between groups [1 and 3], [2 and 3] and [5 and 6] [P=0.008]. Infectious bronchitis live vaccine could increase the AI virus propagation and shedding in co-infected groups [groups 5 and 6]. Altogether, both AI H9N2 vaccines could effectively reduce viral replication and shedding in broiler chicken, however, in order to achieve efficient control of the disease, vaccination should be accompanied with other preventive measurements including biosecurity practices

Detection of avian leukosis virus [ALV] in albumin of Shiraz commercial and local layer flocks using ELISA and RT-PCR

Avian leukosis viruses [ALVs] cause different types of tumours in poultry and can affect the health and egg production of the birds. To investigate the presence of the virus in chicken layer flocks in Shiraz, 222 egg albumen from local layer breeder [25 eggs], local layer grand parent [30 eggs], broiler breeder [60 eggs], commercial layer [46 eggs] and broiler grand parent [61 eggs] were tested by antigen-capture enzyme-linked immunosorbent assay [AC-ELISA]. The results showed that 3.33, 76 and 80% of commercial broiler breeder, local layer breeder and local layer grand parent were positive, respectively. Thirty-five albumen samples were randomly selected and tested by RT-PCR using PU1/PU2 and PA1/PA2 primer sets. The samples with ELISA S/P ratio equal or more than 0.17 were positive by RT-PCR using PA1/PA2 primers. This is the first report of the presence of the ALV in egg albumin samples of chicken layer flocks in Shiraz

effect of ovalbumin and mannose-conjugated ovalbumin on the prevention of salmonella adherence to the intestinal epithelium of chickens

This investigation was designed to determine the effect of intact ovalbumin and mannose-conjugated ovalbumin on the prevention of Salmonella typhimurium adherence to the epithelium of small intestine of chickens. Mannose-conjugated ovalbumin was produced by Maillard-type reaction between chicken ovalbumin and D-mannose at 60[degree]C. The results revealed that incubation up to 96 hrs caused the highest amount of covalent attachment of mannose to the ovalbumin. In order to determine the effect of native ovalbumin and mannose-conjugated ovalbumin on the prevention of S. typhimurium adherence to chicken small intestine, 60 one-day-old chicks were randomly assigned to 3 groups, with two replicates and ten birds per pen. Groups 1, 2 and 3 received normal diet, diet containing 0.5% native ovalbumin and diet containing 0.5% mannose-conjugated ovalbumin, respectively, for 12 days. On day 3, all groups received 1.3 x 10[6] CFU of S. typhimurium orally. On days 4, 7 and 10, two chicks from each group were killed and mean log 10 of CFU [colony forming unit] of Salmonella per 1 g tissues of cecum, liver and spleen was determined. Four chickens from each group were killed on day 12 and were examined as described above. The results showed that in group 3, number of viable Salmonella in cecum, liver and spleen was lower than groups 1 and 2. However, the difference was significant only in cecum on days 4 and 7 [P<0.05]. These preliminary results suggest that mannose-conjugated ovalbumin might be effective in prevention of Salmonella colonization in the epithelium of small intestine if incorporated in the diet of chicks

Isolation and detection of Mycoplasma gallisepticum by polymerase chain reaction and restriction fragment length polymorphism

Mycoplasmas were isolated from tracheal and air sac samples of the suspected flocks to have mycoplasmosis and cultured on Frey's medium. Forward and reverse primers were selected on the basis of known sequences of Mycoplasma gallisepticum [MG] and Mycoplasma synoviae [MS] 16S rRNA genes. These primers successfully amplified a 780 bp fragment of the target DNA in MG. Restriction fragment length polymorphism [RFLP] by three restriction enzymes [REs], Hpal, Hpa II, and Mbol was performed for each PCR product. According to the RFLP results, 55 samples were detected as MG; no MS was detected. The PCR results were confirmed by sequencing of a selected amplicons. Results showed that PCR and RFLP are rapid and useful for diagnosis of both cultured as well as field samples of suspected flocks to have infection with MG. In addition, PCR could be performed with at least 100 CFU of MG per each PCR reaction

Thermostability and efficacy of 1-2 vaccine against Newcastle disease [ND] in Iran: a pilot study

Thermostable vaccine against Newcastle disease [ND] is a potential alternative to chicken vaccination in villages, since cold chain is not needed in this process. The purpose of this study was to investigate thermostability and efficacy of 1-2 vaccine against ND. The vaccine tested for sterility, intracerebral pathogenicity index [ICPI] and 50% embryo infectious dose [EID50]. The wet vaccine stored at 20°C for 1,2 and 4 weeks named A, B and D, respectively. Each preparation [10 [7.5] EID50] was used to inoculate twenty, 4-week-old chicks via eye drop. All groups except the control were vaccinated twice in 2 weeks interval. Haemagglutination inhibition test used for evaluation of the antibody response. Two weeks after the first vaccination, a peak titer of about log.2 [6] and log.2 [4.6] was observed in A and B groups, but D group did not induce any antibody response in their sera. All the vaccinated groups responded to vaccination after second trial and produced mean titers of log.2 [6.2], log.2 [6] and log.2 [5.4] were observed, respectively