Selection for early (precocious) development of Eimeria meleagridis in the turkey

A precocious line of Eimeria meleagridis was developed by repeated propagation of the parasite in young turkeys and collection of the very first oocysts produced following infection. After 20 generations of selection, the prepatent period was reduced by 4-8 hr. Weight gain of poults given this line, from days 0-3 after infection, was significantly greater than that of poults given the parental strain, indicating that selection resulted in a loss of pathogenicity. Poults immunized with the precocious line produced no oocysts following challenge with the parental strain, indicating that immunogenicity was retained following selection. This is the first published report of the selection of a precocious line of Eimeria in the turkey.     

Molecular assay for the detection of Cochlosoma anatis in house flies and turkey specimens by polymerase chain reaction

A 1520 bp region of Cochlosoma anatis mtDNA 16S gene was subjected to DNA sequencing and a 466 bp portion was compared with other protozoan 16S sequences to develop PCR primers specific for C. anatis. This PCR diagnostic method allowed identification of C. anatis from house flies, Musca domestica L., turkey gut, and fecal samples within 6 h after field-collected samples reached the laboratory. House flies detected carrying C. anatis using the diagnostic 374 bp amplicons represented the first record of this protozoan in house flies.     

Characterization of a strain of Eimeria meleagridis from the turkey

An isolate of Eimeria meleagridis Tyzzer, 1927 was obtained by harvesting oocysts from the ceca of a turkey from northwest Arkansas and a pure line was established by infecting birds with a single oocyst. Oocysts were first produced in the ceca of infected birds from 102 to 108 hr after inoculation and were of similar size (mean length X width, 24.9 X 17.0 microm) to those of Eimeria adenoeides Moore and Brown, 1951 and Eimeria gallopavonis Hawkins, 1952. The line was identified as E. meleagridis based upon the development of large schizonts in the midintestine, and small schizonts in the ceca. Two generations of large schizonts were found 48 and 72 hr after infection, and at least two generations of small schizonts were found from 60 to 108 hr after infection. An inoculum of 2 X 10(5) oocysts was found to cause a significant reduction in weight gain from days 0-3 and 0-6 after infection, suggesting that the significance of this species of Eimeria as a pathogen of turkeys should be reassessed.     

Sensitivity of field isolates of Eimeria to monensin in the turkey

A method previously described by Jeffers and Bentley, involving calculation of a growth and survival ratio and optimal anticoccidial activity index, was used to investigate the sensitivity of 23 field isolates of Eimeria obtained from turkey flocks to the ionophorous antibiotic monensin. Isolates were obtained from litter and intestinal samples from several major turkey-growing regions of the United States, and in most cases contained at least two species of Eimeria. A mixture of strains that had been maintained in the laboratory for many years in the absence of exposure to anticoccidial drugs was found to be sensitive to monensin. Six of the field isolates were judged sensitive, seven partially resistant, and ten resistant to the drug, judged by the Jeffers and Bentley criteria. This is the first report of the acquisition of resistance to monensin in isolates of Eimeria from turkey flocks in the United States.     

Polymerase chain reaction-based restriction fragment length polymorphism pattern of porcine reproductive and respiratory syndrome virus directly from lung tissues without virus isolation in Korea.

Polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP) analysis was developed for directly typing porcine reproductive and respiratory syndrome virus (PRRSV) from lung specimens without virus isolation. Twenty nine lung specimens collected from postweaning pigs were isolated for PRRSV. When the PCR products from the 29 lung specimens were digested by the restriction enzymes MluI, HincII, SacII and HaeIII, the RFLP patterns from the 29 lung specimens matched with those from the corresponding PRRSV isolates from each pig. The results suggest that the PCR-based RFLP analysis method may be useful to distinguish PRRSV isolates directly from lung specimens without virus isolation.     

Polymerase chain reaction for definitive identification of Yersinia ruckeri.

Yersinia ruckeri causes enteric red mouth (ERM) disease in salmonids. Serologic identification of Y. ruckeri is hampered by cross-reactivity with other bacterial isolates of fish origin. Oligonucleotide primers incorporating Y. ruckeri unique sequences were designed to amplify a 409 bp fragment of Y. ruckeri 16S rDNA. The primers did not amplify other genetically related Yersinia or a wide variety of other aquatic or piscine bacteria. This assay provides a rapid, definitive identification of Y. ruckeri that is not subject to the variability inherent in serologic methods.     

Use of a real-time polymerase chain reaction-based fluorogenic 5' nuclease assay to evaluate insect vectors of Corynebacterium pseudotuberculosis infections in horses

OBJECTIVE: To develop and use a sensitive molecular assay for detecting the phospholipase D (PLD) exotoxin gene of Corynebacterium pseudotuberculosis in an attempt to identify insect vectors that may be important in transmission of clinical disease in horses. SAMPLE POPULATION: 2,621 flies of various species. PROCEDURE: A real-time polymerase chain reaction (PCR)-based fluorogenic 5' nuclease (TaqMan) system (ie, TaqMan PCR assay) was developed for the detection of the PLD gene in insects. Flies were collected monthly (May to November 2002) from 5 farms in northern California where C. pseudotuberculosis infection in horses is endemic. Three of the 5 farms (which housed a total of 358 horses) had diseased horses during the study period. A total of 2,621 flies of various species were tested for the PLD gene of C. pseudotuberculosis. RESULTS: Evidence of bacterial DNA for the PLD gene was detected in skin biopsy specimens from clinically affected horses and from 3 fly species collected from farms where affected horses were housed. Farms with a high incidence of diseased horses had a high proportion of insects carrying the organism. High percentages of flies with positive results for the PLD gene were observed in October, when most clinically affected horses were observed. CONCLUSIONS AND CLINICAL RELEVANCE: Our results are consistent with the hypothesis that C. pseudotuberculosis may be vectored to horses by flies. Three potential vectors were identified, including Haematobia irritans, Stomoxys calcitrans, and Musca domestica. The organism can be identified in up to 20% of house flies (Musca domestica) in the vicinity of diseased horses.     

沙门氏菌简便的核酸检测技术

利用聚合酶链反应技术，特异性扩增沙工菌Ｈ１基因的２６９ｂｐ片段。８株标准一菌和３株阳性菌检测结果完全相符，并对３０株分离的疑似沙门氏菌进行了检测。采用５０μｌ体系，引物为自行设计各２０６割寡聚苷酸，各１μＭ；ｄＮＴＰｓ各１００μＭ，Ｔａｑ本科Ｕ。二温段水浴扩增３５循环，条件为预变性９７℃７ｍｉｎ，变性９４℃６０ｓ，复性和延伸６０℃６０ｓ，终延伸７２℃７ｍｉｎ。     

Efficacy of amprolium for the treatment of pathogenic Eimeria species in Boer goat kids

This study evaluated the efficacy of two different doses of amprolium in goats heavily infected with pathogenic Eimeria species. Forty Boer goat kids ranging from 3 to 5 months of age with naturally occurring coccidiosis were randomly divided into 2 groups and treated orally with amprolium at doses of 10mg/kg daily for 5 days (n=20) or 50mg/kg daily for 5 days (n=20). The Eimeria oocyst per gram concentrations were significantly reduced on day 7 in the kids that received amprolium at 50mg/kg, however oocyst concentrations were not significantly reduced in goats that received the 10mg/kg dose. Out of 100 Eimeria oocysts identified from a pooled fecal sample, E. christenseni was the most frequently identified (52%) coccidial species present. The results of this trial indicate that amprolium can be an effective treatment for pathogenic Eimeria species in goat kids, however higher and extralabel doses (50mg/kg) should be used.     

Development of a competitive enzyme-linked immunosorbent assay for detection of turkey coronavirus antibodies

A competitive enzyme-linked immunosorbent assay (cELISA) was developed for detection of turkey coronavirus (TCV) antibodies. The cELISA utilized a recombinant baculovirus (Autographa californica nuclear polyhedrosis virus)-expressed TCV nucleocapsid (N) protein and biotin-labeled TCV N protein-specific monoclonal antibody. Sensitivity and specificity of the cELISA for detection of TCV antibodies were determined by comparison with the indirect fluorescent antibody test (IFAT) with 1269 reference, experimentally derived, and field-origin sera. Sera with discordant cELISA and IFAT results were further evaluated by western immunoblot analyses. The cELISA detected antibodies specific for TCV and infectious bronchitis virus, a closely related coronavirus, but did not detect antibodies specific for other avian viruses. A high degree of concordance was observed between the cELISA and IFAT; sensitivity and specificity of the cELISA relative to IFAT were 92.9% and 96.2%, respectively. Western immunoblot analyses provided additional evidence of cELISA specificity. The findings indicate that the cELISA is a rapid, sensitive, and specific serologic test for detection of TCV antibodies in turkeys.