Seroprevalence and genotyping of avian infectious bronchitis virus detected from Iranian unvaccinated backyard chickens
Background and Objectives: Different epidemiological studies have found that backyard chickens are a reservoir for poultry diseases. Most backyard chicken flocks have a poor level of biosecurity, which increases the risk of spread of diseases. In recent years, the number of backyard chickens has been on the rise in Iran. However, the health status of backyard flocks is still poorly documented. Thus, this study aimed at examining the seroprevalence of antibodies against infectious bronchitis virus (IBV) and molecular surveillance and genotyping of IBV among backyard chickens (without vaccination history) in Mazandaran province, North of Iran, 2014. Materials and Methods: A total of 460 blood samples of unvaccinated backyard chickens in the mentioned area were tested for antibodies against IBV using commercial ELISA. Also, cecal tonsils were collected from 75 chickens in the same area. Real time RT-PCR (for detection) and RT-PCR and sequencing spike gene were performed. Results: The seropositivity rate was 54.5%. In addition, we detected 793/B, Variant 2, and QX in the backyard flocks and performed phylogenetic studies on them. The phylogenetic study revealed that the detected genotypes had high homology with IBV strains that were infected broilers, pullets, and layers in Iran. Conclusion: There is a need for continuous monitoring of IBV among avian species to complete the epidemiological map and work on the pathogenesis of Iranian IBV strains in Iranian backyard chickens.
Detection of the Chinese Genotype of Infectious Bronchitis Virus (QX-type) in Iran
Case Report: Recently a 20-day-old layer flock with mortality has been submitted to the PCR Lab. Infectious Bronchitis Virus (IBV) has been detected in the clinical samples. Results: A phylogenetic tree based on a partial S1 gene sequence showed Iranian IBV variant located in LX4-type cluster. This cluster include all QXIBV-type detected in China and European countries. The highest sequence homology (> 99%) was found with that of a group of the Chinese QX but less similarity with European QX-like (>95%) and another Chinese QXIBV (>94%). Conclusion: Comparison of Nucleotides sequence with H120 and 4/91 IB vaccines shows only 76.9 and 79.7 identity, respectively.
Epidemiological classification of infectious bronchitis virus isolated in Korea between 1986 and 1997.
Forty Korean isolates and four reference strains of infectious bronchitis virus (IBV) were classified by reverse transcriptase-polymerase chain reaction and restriction fragment length polymorphism (RFLP) analysis. Each Korean isolate was isolated from different types of commercial chicken flocks between 1986 and 1997. RFLP patterns of an amplified DNA fragment (1722 bp) containing the S1 gene of IBV digested by restriction enzyme HaeIII showed that the 40 Korean isolates were classified into five genotypes, I to V. Six of them belonged to genotype I which had the same HaeIII and XcmI cleavage patterns with Massachusetts type (H120 and M41) but the other four genotypes had a different HaeIII cleavage pattern from the four reference IBV strains used in this study. Genotype III seemed to be the major type as 29 of the 40 isolates belonged to this type which was consistently found in the chicken flocks since 1990. On the other hand, genotypes II, IV and V were found in the field only in 1986, 1995 and 1995, respectively. Five isolates selected from each of the five genotypes were inoculated into 1-day-old specific-pathogen-free chicks to evaluate their pathogenicity. Genotype III induced 50% mortality as well as severe renal urate deposition on the kidneys but the other four genotypes only showed respiratory distress at 1 to 2 days after inoculation. Live H120 vaccine protected chicks against challenge with isolates selected from genotype I, but not genotypes IV to V. A live KM91p120 strain selected from major genotype III did protect chicks against challenge with isolates from genotype III, in addition to other genotypes, including two recent isolates of genotypes IV and V.