JOURNAL OF VETERINARY MICROBIOLOGY
Year:2013 | Volume:9 | Issue:1 (26)|Papers Count:11

The aim of this study was to investigate serotypes and bacterial capsule presence of Streptococcus iniae starins, the cause of streptococcosis in rainbow trout farms of Iran. The study also aimed to identify the minimum inhibitory concentrations (MICs) of Zataria multiflora and Rosmarinus officinalis essential oil against these strains and to assess the growth behavior of them. The results showed, most strains from rainbow trout farms were serotype I and all serotypes had complete bacterial capsule. The MIC of Z. multiflora to Streptococcus iniae serotype I and serotype II was 0.06 µl/ml and the minimum bactericidal concentrations (MBCs) were 0.5 and 0.12-0.25 ml/ml. minimum inhibitory concentrations of R. officinalis to serotype I and II were in range 0.12 to 0.25 ml/ml and 0.12 ml/ml, respectively. MBCs of R. officinalis against serotype I and II were >1 ml/ml and 0.5-1 ml/ml According to disk diffusion assay results, antimicrobial activity of Z. multiflora essential oil is significantly higher than R. officinalis. The growth of strains was reduced by increasing essential oils concentration. Our results suggested that Z. multiflora and R. officinalis essential oils could be effective for the inhibition of streptococcosis in rainbow trout farms.

Cysticercus tenuicollis is the larval stage of Taenia hydatigena, the presence of which has been reported in wild and domestic ruminants throughout the world. It is a common parasite of sheep in Iran. This study was undertaken to determine Cysticercus tenuicollis infection rate, to rank the severity of its hepatic lesions and to describe the pathological characteristics of the lesions in sheep. Out of 340 examined sheep (259 in Najaf Abad and 81 in Joneghan abattoir), 65 (25.48%) and 30 (37%) were infected with Cysticercus tenuicollis, respectively. This cyst was observed in different anatomic locations including liver, mesentery, omentum, peritoneum and diaphragm. There was no Cysticercus tenuicollis in the heart and lung of slaughtered sheep. The liver of the infected sheep showed multiple red to brown or greyish-white tortuous tracts. The histopathological examination of newly formed hepatic lesions revealed migratory tracts filled with red blood cells, fibrin and tissue debris. The sections of Taenia hydatigena larvae, hepatocellular degeneration, necrosis, and infiltration of inflammatory cells were observed in the migratory canals too. Caseous necrosis and calcification were seen in the central part of old migratory tracts. A large number of macrophages or epithelioid cells and giant cells were seen around the necrotic area. These structures were surrounded with collagenous connective tissue infiltrated by lymphocytes and plasma cells. To rank hepatic lesions, the number of migratory tracts, in hepatic surfaces were counted and assigned to one of the following categories including mild (1-4 migratory tracts), moderate (5-10) and severe (>10) and the results were 76.19%, 19.05% and 4.76%, respectively. The results of this study show that the migration of Taenia hydatigena larvae can cause economic losses and the disease control programs are recommended and emphasized.

To compare the anti-brucella antibody in veterinary and non-veterinary students, blood samples were taken from 167 veterinary and 106 non-veterinary students of Shahid Chamran University of Ahvaz, Iran. All sera were tested for Brucella abortus strain antibodies by rose bengal, wright and 2-mercaptoethanol test. 15(8%) of the veterinary students had antibodies to Brucella abortus strain in rose bengal test and had titre of 20 to 40 in wright and 2-mercaptoethanol test. None of the non-veterinary students were positive in rose bengal test. Statistical analysis showed there was significant difference between veterinary with non-veterinary students (P=0.001) and the risk of Brucella infection in veterinary was higher than non-veterinary students (OR=39.1, 95% CI: 1.9-539.2). There is no-significant correlation between titer of anti-Brucella antibody with sex (P=0.357) and the grade of students (P=0.268). Regarding the result of this study and the high risk of Brucella infection in veterinary students, it is emphasized that these students should be careful when they are exposed to the Brucella infected animals.

This study was conducted to compare the efficacy of sheep humoral immune response induction of two commercial adjuvants used routinely in veterinary vaccines. Forty-eight (48) local native-bred lambs of 2 to 3 months old were chosen and divided into four groups; the treatment groups were immunized twice, two weeks apart, with 0.2 mg of pyolysin toxoid in combination with aluminum hydroxide or ISA70 adjuvants by subcutaneous injection. The lambs in the control groups received the same sterile normal saline solution with equal amounts of aluminum hydroxide or ISA70 adjuvants at the same times. The blood samples were taken in days 14, 28, and 98 from all of the lambs after the first immunization, and their sera were measured for anti-pyolysin antibodies by hemolytic neutralization assay. According to the results, the mean titers of anti-pyolysin antibodies in immunized lambs with pyolysin toxoid and ISA70 adjuvants were significantly higher than the mean titers of antibodies in the group that received toxoid with aluminum hydroxide adjuvant (P<0.05). It appears that the use of ISA70 adjuvant in vaccines is more efficacious than hydroxide aluminum adjuvant.

The relation between mucosal immunity and resistance to infectious bronchitis virus (IBV) has been known. Thus, for the evaluation and comparison of mucosal immunity response against IBV, 450 one-day-old broiler chickens were divided and vaccinated against IBV according to different approaches. The chickens in different groups were vaccinated against live IB vaccine in one day old, 8 days old,1 and 8 days old, 1, 8 and 18 days old in growing period. The chickens were slaughtered 10 days after the end of each vaccination program and when they were 28 days old. The nasal and tracheal samples were dissected and washed. Specific IgA against IBV in mucosa of respiratory was assayed using ELISA with goat anti-chicken IgA conjugated with horse radish peroxidase. The results revealed there are no significant differences in mucosal immunity response following the administration of the first and second IBV vaccines. Following the administration of IBV vaccine in the third time, it induces significantly higher mucosal immunity response than expected which can, in turn, induce higher resistance to pathogenic IBV.

The accessory gene regulator (agr) is a central system that controls the expression of Staphylococcus aureus virulence factors and four allelic groups (designated as agr I-IV) have been identified in this system. The aim of this study was to ascertain the frequency of the different agr groups in S. aureus isolates recovered from the nasal cavity of healthy cattle, sheep, and goats. In the current study, 26 S. aureus isolates were recovered from the nasal cavity of 79 cattle (n=4), 78 sheep (n=11), and 44 goats (n=11). Then, the isolates were agr typed by multiplex polymerase chain reaction (mPCR). Despite the low prevalence of S.aureus in the nose of cattle (5.06%), this organism is more commonly isolated from the nose of sheep (14.1%) and goats (25%). Of 4 S. aureus isolates obtained from cattle, 3 were ascribed to agr type I and 1 to agr type IV. Seven out of 11 sheep nasal isolates were of agr type I, the other 4 being agr type III (n=3) and agr type II (n=1). Goat nasal isolates were distributed mainly across agr types I (n=10). Only one of the goat isolates was of agr type II. Overall, a low prevalence of S. aureus were found in the nose of cattle compared to small ruminants. Also, S. aureus isolates with agr type I were common and might be capable of colonizing the nasal cavity of ruminants, most likely by regulatory adaptation to the nose environment. Further studies will be necessary to define how the type of agr regulatory system might affect S. aureus nasal colonization.

Avian influenza virus has been recognized as one of the most important pathogen in poultry that caused economic losses to the poultry industry of Iran. Rapid detection and pathotyping is the important priority in order to prevent extension of disease in Iran. RT-PCR method was used for the rapid detection of influenza viruses. The amino acid sequence of cleavage site of hemagglutinin was considered as a molecular determinant for the prediction of pathogenicity influenza viruses. In this study, 160 tracheal swabs samples were taken from 20 poultry farm to monitor influenza infection in North Khorasan province. RT-PCR assay was developed based on the most common genotype in Iran detecting type A and H9, H5 and H7 subtypes by specific primers targeting Matrix (M) and Hemagglutinin(HA) genes, respectively. The samples which were positive as type A influenza inoculated to embryonated eggs of 9-10 days. After 3-5 days, the allantoic fluids were tested with Hemagglutinin assay. The samples that contained HA activity were inactivated with formalin 0.1%. These fluids were used for RNA extraction. A segment of 432bp was amplified by RT-PCR and nucleotide sequencing. The results showed that four poultry farms were positive for type A of influenza virus. All of them were negative for H5 or H7 but positive for H9 virus. The sequence analysis of hemagglutinin revealed that four isolates shared a KSSR motif at the cleavage site of HA. Although this motif represented low pathogenicity in poultry, it was different from previous Iranian isolates. As a result RT-PCR assay based on common genotype in region was considered as a rapid test for the detection of influenza viruses. The cleavage site sequence analyses indicated that these viruses have the potential for emerging highly pathogen influenza viruses. Therefore, continuous monitoring of viruses is being recommended.

This study was conducted to investigate the toxic effects of Aflatoxin on the immune system and blood parameters of broilers. For these purposes, 120 Ross 308 broiler chicks were used in a completely randomized design with 3 treatments, 4 replicates and 10 chicks in each unit. The chickens were reared for 35 days on the ground. The treatments were as follows: 1-control (no dietary Aflatoxin B1), 2- diets containing 250 ppb of Aflatoxin B1 and 3- diets containing 500 ppb of Aflatoxin B1. The minimum length of the ileum and intestine belonged to chicks receiving 500 ppb Aflatoxin level. After the blood samples were taken, total protein, albumin, bilirubin, glucose, uric acid, calcium, phosphorus, and AST, ALT and g-GT were measured. The titration tests of Newcastle and influenza disease, in two steps (25 and 34 days) were performed. At the age of 25 days, before administering the Newcastle-influenza vaccine, the blood samples were collected from two chicks in each group. The HI antibody titers against Newcastle and influenza were determined in them. In addition, in 34 days of age, blood samples were taken from the first stage chickens and the antibodies were measured again. No significant changes were observed in the levels of calcium, phosphorus, albumin and total protein in the serum of experimental broilers compared with birds receiving the basal diet. As the levels of Aflatoxin B1 increased from 250 to 500 ppb in feed, the serum levels of glucose, total bilirubin and AST also increased. In contrast, the level of direct bilirubin decreased significantly. HI titer against influenza and Newcastle disease in the second stage (34 days) showed a significant decrease compared to the basic treatment. The findings also evinced that Aflatoxin causes changes in the blood parameters, kidney and liver damages and decreased immune functions against Newcastle disease and influenza in broiler chickens.