ARCHIVES OF RAZI INSTITUTE
Year:2002 | Volume:- | Issue:53|Papers Count:11

Five infectious bronchitis viruses (IBV) were isolated from commercial chickens. One of them was isolated from a layer flock vaccinated with H120 on day old and the others were originated from broiler flocks without receiving the vaccine. All the isolates caused embryo mortality and or dwarfing, stunting, curling, clubbing of the down and urate deposits in the kindney. In tracheal orgn cultures (TOCs), the isolates caused typical ciliostasis. Electron microscopy confirmed all the isolates have coronavirus morphology. The isolates were also confirmed by dot-immunobinding assay using polyclonal antibody to IBV. In one-day-old specific pathogen free chicks, all the isolates could induce typical respiratory distress of IB at 36-48 h postinoculation by intraocular route. Virus-neutralization test showed that two isolates were recovered from broiler flocks did not neutralize by monospecific. Massachusetts (Mass) antiserum, indicating the presence of other serotypes in commercial chicken flocks in Iran.

Avian influenza (AI) is a viral disease of poultry worldwide and earlier diagnosis of the disease is very important in control programs. Among immunohistochemical staining techniques, the poultry laboratory diagnosticians have used indirect immunoperoxidase (IIP) assay for rapid diagnosis of avian viral diseases. In this study the IIP assay was optimized, then compared with the standard AI virus (AIV) isolation procedure on trachea, lung and kidney tissue samples. The samples were prepared from broiler chicken experimentally infected with the reference H9N2 subtype of AIV as well as clinical specimens. For preparation of frozen tissue sections samples were embedded in OCT compound and put rapidly in liquid nitrogen and kept at -70°C. The tissue sections were fixed and subjected to IIP assay by using a type A specific polyclonal and goat anti-chicken peroxides conjugated antibodies. The sensitivity, specificity, positive and negative predication values IIP assay was 78, 90, 80 and 88% respectively.  

An experimental avian influenza (AI) oil-emulsion vaccine was formulated with a ratio of 4 parts oil adjuvant ISA-70 and 1 part formalin inactivated A/Chickne/Iran/ZMT-101(101)/98(H9N2) antigen. Thirty 2-week-old Aryan broilers and thirty 2-week-old white Hy-line pullets were vaccinated subcutaneously. The latter was delivered a booster 10 weeks after primary vaccination. All vaccinated and control birds were bled for hemagglutination-inhibition (HI) test at least one week intervals. Half of the birds were challenged via intranasal and intravenous routes with a h9N2 strain at 8 and 27 weeks of age in broiler and layer birds, respectively. High HI titers were observed in both vaccinated and unvaccinated birds, when examined at 2 weeks post-challenge (PC). Viral isolation or shedding from tracheal and cloacal swaps of both vaccinated broiler and layer was decreased at 2 weeks PC, as compared with unvaccinated control birds. All control birds became morbid, and egg production decreased on day 3 PC. The results suggested that the inactivated oil-emulsion H9N2 AI vaccine may be protects both chickens against viral shedding and egg drop in filed conditions.

This experiment was conducted to determine the effects of feed restriction (FR) on performance and the immune system of Arian and Ross strains. Feed efficiency was significantly better for restricted birds. Body weight (BW) of the restricted chickens was significantly lower than those of the ad libitum group at day 42. Arian strain had lower BW at day 21 but higher BW at day 42 than Ross strain. Birds in FR group showed a significant increase in percentage of CD4+ (helper T cell) and decreased CD8+ (cytotoxid T cell) at day 21 and 42. T cell subsets of Ross and Arian birds was not significantly different on day 21, but in day 42 the Arian chickens had higher CD4+ and lower CD8+ than those of Ross chickens. Antibody response to sheep red blood cells was significantly higher in the birds on the FR group at day 21. Antibody titer was not affected by strain at day 21 but Ross chickens had higher antibody titer than Arian Chickens at day 42. The results indicated that the feed restriction may have some advantages, mainly by increasing feed efficiency and immune system competence.

Forty-eight isolates of hydatid cyst collected from sheep and camels slaughtered in different areas of Iran were analyzed by polymerase chain reaction and restriction fragment length polymorphism techniques. The results indicated that the isolates could be categorized into two distinct and uniform genotype grouping, the camel/dog strain group (Genotype 6) and cosmopolitan common sheep strain group (Genotype 1) of E. granulsus. These isolates can potentially act as a risk factor for human health in the country.

The inhibitory effects of aflatoxin B1 (AFB1) on hepatic DNA biosynthesis was compared in growing and day-old chickens. A single ip dose of AFB1 (0, 25, 50,100 or 200mμg/kg BW) was administered to groups of then and day-old female Hybro-broiler chickens pre-treated with [3H]-thymidine. All the chickens were given labeled thymidine 22h prior to AFB1 administration and sacrificed 2h after AFB1 injection. Livers were removed and processed for DNA isolation and estimation of thymidine incorporation into nuclear DNA. A differential inhibitory effect of AFB1 on DNA biosynthesis in hen and chicks was noticed. The overall results showed that as compared to growing chickens, youngers are relatively more refractory to AFB1-induced inhibition in DNA biosynthesis. A single dose of AFB1 (25.50, 100 or 200 mμg/kg BW) administered to day-old chickens caused on average 22-28% inhibition in DNA biosynthesis. Whereas under similar conditions of dose and treatment to the growing group, a greater (36-47%) but dose-dependent inhibition in hens liver DNA is recorded.

The clinical and laboratory findings associated with Cryptosporidium infection in four broiler flocks were reported. The severity of Cryptosporidium-induced disease is greatly compounded by the presence of other pathogens. Tracheal swab culture on blood agar revealed a bacterium which identified as Ornithobacterium rhinotracheale by further biochemical and serological characteristics. This isolate was resistant to enrofloxacin and flumequine, and sensitive to ampicillin and tiamulin. Escherichia coli isolated from heart of the carcasses were resistant to all conventional antibiotics. Eimeria tenella was also detected in the ceca of some carcasses of this flock. Simultaneous isolation of C.baileyi, Clostridium perfringens type A, and E. coli serogroup 08 in a broiler flock affected by gangrenous dermatitis and serious weight gain loss was also reported.  

Fourteen isolates of infectious bronchitis virus (IBV) from Iran in 2001 were typed by a type-specific multiplex RT-PCR. The RT-PCR reaction has been designed to detect and differentiate strains of Massachusetts, D274 and 4/91 (793/B) types. Based on the DNA band produced in RT-PCR, twelve isolates were classified in the type Massachusetts and two isolates (13/2001 and 14/2001) in the type 4/91. The identity of isolate 14/2001, as being from the type 4/91, was also confirmed by sequence analysis of its RT-PCR product. The result of this study shows the presence of at least two types of IBV in Iran.

Ten Hybridomas secreting monoclonal antibodies directed against the F-glycoprotein of MK13 (Iranian Isolate) strain of Newcastle disease virus (NDV) has isolated which 6 of them showed positive reaction in different tests. All of these antibodies are IgM class with #k, chain which showed sharp and single band on F-Protein (56000 Dalton) in western blot assay. All these antibodies reacted with same epitope on competitive ELISA. On cross reactivity analysis with different avian viruses all were specific to NDV only and did not show any reaction with other virus. the importance and application of these antibodies would be on specific identification of NDV, highly purification of F-protein of NDV specially on preparation of recombinant F-protein on subunit vaccine, developing anti-idiotype vaccine and also blocking the cleavage site of F-protein which resulting in decreasing pathogenicity of virus.

To study the effect of gamma rays on viral pathogens of animal sera, samples of three virus preparations which belonging to different families were exposed in the frozen state to cobalt-60. Each sample was tested for reduction in virus titer. The rate of inactivation for viruses tested indicated that gamma radiation (cobalt60) proves to be an effective method for inactivation of some viruses which presence in animal sera.

During 1993 to 1999, 28 endometrial biopsies of infertile mares were examined. The tissue samples were fixed in 10% of buffered formalin, sectioned and stained with H&E method. The appropriate categorization based upon Kenney 91986) technique was used. Also in histopathologic examination, there were acute and chronic endometritis, periglandular and interstitial fibrosis, hemorrhage, glandular atrophy, cystic glands, lymphatic dilation, hypertrophy and hyperplasia of endometrial glands. In proportional frequency acute and chronic endometritis, were 21.4% and 10.7%, respectively. Other lesions such as endometriosis and normal endometrium were 25% and 42.9%. Edema, hemorrhage and fibrosis were the most frequent lesions. 14 cases 950%) were type I, 9 cases (31.2%) were type IIA. 5 cases (17.8%) were type IIB and no case was in type III. It has been calculated that about 50% of infertile mares had a normal endometrium.