فهرست مطالب a. hojabr rajeoni

Hemagglutination Inhibition (HI) test is a universal method in veterinary laboratories that has low sensitivity and high specificity in determining the level of antibody. This study aimed to evaluate the repeatability of HI test and to determine the suitable antigen for HI test. Two experiments were conducted in this study. In the first, 60 serum samples were divided into four groups, including negative, low, medium, and high titer serums for Newcastle virus. Also, to evaluate the repeatability of the HI test results, eight pairs of repeating serums were placed from all four serum groups. The sera were sent to 11 different veterinary laboratories, and asked to determine the Newcastle HI titers by standard protocols. In second experiment, 41 sera were used to determine the appropriate antigen using five antigens (Clone Lasota, Lasota, B1, commercial and laboratory antigen) for the HI test. the first experiment showed that most laboratories could identify high titers, but there is a significant difference in determining zero, low, and medium titers. Also, based on results obtained from each of laboratories, it was found that the reproducibility of HI results within a laboratory is low.  In the second experiment, the best antigen was determined in terms of the same answers for use in the HI antigen test of Lasota Clone vaccine. This study is the first study on the quality control of the HI in Iran. The results showed that the quality of test is not satisfactory, and the IVO and research centers should standardize this test.

During the breeding season, commercial poultry flocks are exposed to various viral, bacterial, mycoplasma, and fungal infectious agents. Vaccination and field challenges are examples of this infectious. Isolation, serological test, and molecular diagnosis were used to evaluate the vaccine response and laboratory diagnosis. Analysis of the serum response is one of the diagnostic challenges between laboratories and clinicians.  The aim of this study was to investigate the effect of avian influenza virus infection on the results of Newcastle vaccines in poultry flocks. To do this, the effect of influenza (H9N2) respiratory infection on serum response to live Newcastle disease vaccine was investigated and the results of hemagglutination inhibition test were analyzed. The results showed that the presence of avian influenza virus increased the serum response to the Newcastle disease vaccine and increased the titer's dispersion so that in the study of the titers, some of the titers appeared to indicate disease. It can be analyzed that the influenza virus may have caused inflammation of the trachea to increase the penetration of the vaccine virus into the trachea and create a stronger immune response. In fact, this study demonstrates the synergistic effect of the H9N2 influenza virus and the Lasota vaccine virus. In poultry farms and especially broiler farms, due to the multiplicity of vaccines used and the high volume of challenge, for serological testing, it is recommended that a complete serum profile be used to survey titers all common respiratory factors.

Newcastle disease virus (NDV) causes economic losses to the poultry industry. ND vaccines are used in different forms and include one of the strains. The purposes of this study were comparing titer and protection created by killed vaccines with different NDV seeds against genotype VII, comparing the autogenous genotype VII vaccine with conventional vaccines, comparing the effect of adjuvants in making the autogenous vaccine, and examining vaccination of live Newcastle vaccine on titer and protection created with inactivated ND vaccines against Genotype VII vaccines. The study was conducted in seven groups of day-old chicks. In addition to the control group, all groups injected subcutaneous vaccines containing V4, Ulster 2C, Lasota, G7 genotype with Adjuvant A or B, and Lasota with a live Lasota vaccine at 14 days old. At old-day, the chickens received the B1 vaccine. Serum was given before the challenge, at the age of 35 days and 14 days after challenge. At 35 days old, chickens were challenged by the ocular-nasal method with the genotype VII virus and the mortality was assessed up to 7 days after the challenge. The results of titration rate in 3 weeks after injection showed the Ulster 2C strain vaccine had a higher titer (1.26 ±7) than other groups (insignificant difference P>0.05). In Lasota vaccine group, Genotype VII with Adjutant A and control group, the mortality rate was 13.3, 10, and 40 percent, respectively. The results showed that different commercial vaccines in terms of titers do not have significant difference (titer and survival).

Fowl adenoviruses (FAdVs) are responsible for a variety of clinical symptoms, with an increasing significance in the poultry industry throughout the world. Typical diseases caused by FAdVs include inclusion body hepatitis (IBH), hepatitis-hydropericardium syndrome (HHS), gizzard erosion (GE), respiratory disease, and hemorrhage in muscles and organs.

During 2020, broiler chickens from the north of Iran showed ecchymotic and petechial hemorrhages in thigh and breast muscles at the slaughterhouse. Hemorrhages were observed in 10% to 60% (with an average of 20-30%) of chicks per flock. To find out the etiology of these lesions, the present study was conducted.

Different environmental factors were investigated, and FAdV, infectious bursal disease virus (IBDV), and chicken infectious anemia virus (CIAV) were detected using molecular assays.

Among the viruses tested, FAdV was detected by polymerase chain reaction (PCR), and sequence analysis clustered the virus into species E, serotype 7.

This is the first report on FAdV-7 existence among poultry in Iran. Effective screening of the chicks at slaughtering age should be performed from the whole country.

Avian metapneumovirus (aMPV) infection has significant economic impacts on the poultry industry all around the world. The aim of this study is molecular investigations of different types of aMPV in broiler farms in different provinces of Iran from 2016 to 2018. Tracheal and oropharyngeal swabs were collected from two hundred broiler chickens with respiratory signs in ten provinces of Iran, including Kurdistan, West Azerbaijan, Semnan, Esfahan, Sistan and Baluchistan, Qazvin, Khuzestan, Fars, Gilan, and Khorasan Razavi from February 2016 to December 2018. After RNA extraction, the presence of aMPV was confirmed using N gene special primers. Then, subtype-specific primers were utilized to differentiate the specific subtype. All positive samples were sequenced. As a general trend, the percentage of aMPV positive chickens increased gradually over time. All samples were clustered together and placed in the subtype B aMPV group. Although 2 samples from 2016 and 2 samples from 2018 were placed in a separate branch, most of the current study samples of 2016, 2017, and 2018 revealed six segregated sub-branches, and they were placed close to other isolates of 2011 and 2013 from Iran. The current field study indicated the presence of aMPV in a considerable number of areas in Iran. Thus, the role of this virus in broiler respiratory complex should not be neglected.

Avian infectious bronchitis (IB) is an infectious viral disease of chickens. The effective protection of chickens against many different infectious bronchitis virus (IBV) variants is not achieved unless the circulating genotypes in the region are identified and the cross-protection of the potential of vaccines in use is assessed.

In a monitoring program of IBVs, a new genotype was identified in the north of Iran, 2019. This work was conducted to isolate and characterize this new IBV genotype.

Tracheal tissues were collected from chickens showing signs of respiratory involvement. Specimens were homogenized and inoculated to the allantoic fluid of embryonated specific pathogen-free (SPF) eggs. Infectious bronchitis virus was detected using real time-polymerase chain reaction (RT-PCR). The hypervariable region of the IBV S1 gene was amplified for sequencing.

Positive samples were phylogenetically analyzed, and both positive isolates were clustered with Q1 IBV strains.

This is the first report of the Q1 outbreak in Iran. More investigations are needed to find the role of Q1 IBV in the respiratory disease complex of chickens.