Physical, chemical, and serological characterization of avian rotaviruses     

S Y Kang  K V Nagaraja  J A Newman 《Avian diseases》1988,32(2):195-203

Physical, chemical, and serological characterization of rotavirus isolates from turkeys was done. Cesium chloride (CsCl)-gradient isopycnic centrifugation of infected cell cultures revealed the presence of rotavirus particles of three different densities. They were double-shelled, single-shelled, and core particles. The double-shelled particles had a buoyant density (in CsCl) of 1.34 g/cml3, and that of single-shelled particles in CsCl was 1.36 g/cm3. The buoyant density of core particles in CsCl was greater than 1.40 g/cm3. These rotavirus isolates were not inactivated by chloroform and were relatively stable at pH 3.0. Their replication was not affected by 5-bromo-2'-deoxyuridine. Avian rotaviruses were not completely inactivated by heat treatment of 56 C for 8 hr. All six avian rotavirus isolates examined were antigenically related to each other. However, there was no antigenic relationship between mammalian rotaviruses and the avian rotavirus isolates examined.  相似文献   

Ruminal evacuation's effect on microbial activity and ruminal function   总被引：1，自引：0，他引：1  

G Towne  T G Nagaraja  C Owensby  D Harmon 《Journal of animal science》1986,62(3):783-788

The influence of evacuating, mixing and returning ruminal contents on microbial populations, volatile fatty acid (VFA) concentrations and liquid flow rate was investigated with four ruminal-cannulated Hereford steers (247 kg avg wt). Ruminoreticular contents were sampled, then completely removed, mixed for 5 min and returned to the rumen. Subsequent samples were taken immediately, 1 h and 4 h later. Non-evacuated steers were sampled at identical time intervals either 1 d before or after evacuation. Averaged over time, there was no significant difference between evacuated and non-evacuated steers in total anaerobic, cellulolytic and facultative bacteria, protozoa, oxidation-reduction potential, VFA concentrations, and liquid flow rates. There were no treatment X time interactions and, except for holotrich protozoa and VFA, no differences from time of sampling. Ruminal evacuation does not appear disruptive to anaerobiosis or detrimental to ruminal microorganisms and digestive processes.  相似文献   

Characterization of viral polypeptides from avian rotavirus     

S Y Kang  K V Nagaraja  J A Newman 《Avian diseases》1987,31(3):607-621

The synthesis of avian rotavirus (AvRV-1) polypeptides in MA 104 cells was investigated. Extracts of cells labeled with either [35S]methionine or [3H]mannose were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Viral protein synthesis was detected first at 6 hours postinfection. Ten major viral polypeptides were detected at this time. The presence of five viral structural proteins (100K, 90K, 88K, 45K, and 37K) were demonstrated in AvRV-1-infected cells by immunoprecipitation analysis. One structural polypeptide (37K) was identified as a glycoprotein. Two viral polypeptides (30K and 28K) were identified as nonstructural glycoproteins. By tunicamycin inhibition of glycosylation, a 32K polypeptide was identified. This 32K polypeptide later was proven to be the precursor of 37K structural glycoprotein by immunoprecipitation analysis, beta-N-acetylglucosaminidase H (Endo H) treatment, and peptide mapping analysis. Avian rotavirus contained high-mannose oligosaccharide content in the glycoproteins similar to the glycoproteins of mammalian rotaviruses.  相似文献   

Primary isolation and identification of avian rotaviruses from turkeys exhibiting signs of clinical enteritis in a continuous MA 104 cell line   总被引：4，自引：0，他引：4  

S Y Kang  K V Nagaraja  J A Newman 《Avian diseases》1986,30(3):494-499

Avian rotaviruses were isolated from turkeys with enteritis using MA 104 cell line. MA 104 cells were suitable for primary isolation and propagation of avian rotaviruses. Trypsin appeared essential for the enhancement of infectivity and the occurrence of cytopathic effect (CPE). Serum neutralization (SN), electron microscopy (EM), and analysis of genomic RNA were done to identify and confirm the identity of rotaviruses. Electrophoretic migration patterns of genomic RNA from avian rotaviruses were examined, and they were compared with those from mammalian rotaviruses. The migration patterns differed between these groups.  相似文献   

Factors affecting the leukotoxin activity of Fusobacterium necrophorum.     

Z L Tan  T G Nagaraja  M M Chengappa 《Veterinary microbiology》1992,32(1):15-28

The effect of cultural conditions on the production of leukotoxin by biotypes A and B of F. necrophorum was investigated. Biotypes A and B were grown in prereduced, anaerobically sterilized, brain-heart infusion (BHI) broth. The average leukotoxin titer of culture supernatant was 18 times higher from biotype A strains than from biotype B strains. Leukotoxin activity peaked during the late-log and early-stationary phases of growth, then declined precipitously in both biotypes. F. necrophorum biotype A was grown in different media (BHI, liver infusion, and Eugon broths), at various pH (6.6, 7.3, 7.7, and 8.2), incubation temperatures (30, 35, 39, and 43 degrees C), redox potentials (-352 to +375 mV), and iron concentrations (less than 0.2, 4.2, 42.1, and 361.4 microM). Anaerobic BHI broth with pH from 6.6 to 7.7 at 39 degrees C incubation temperature supported maximal F. necrophorum growth and leukotoxin production. The optimum redox potential for F. necrophorum growth was in the range of -230 to -280 mV. However, the presence of titanium III citrate or dithiothreitol (7.78 mM) in the medium decreased (P less than 0.05) the leukotoxicity of F. necrophorum. Low iron concentration (less than 0.2 microM) decreased (P less than 0.05) growth rate but not leukotoxin activity of F. necrophorum, whereas high iron concentration inhibited the leukotoxin activity.  相似文献   

Evidence of avian pneumovirus spread beyond Minnesota among wild and domestic birds in central North America     

Bennett RS  Nezworski J  Velayudhan BT  Nagaraja KV  Zeman DH  Dyer N  Graham T  Lauer DC  Njenga MK  Halvorson DA 《Avian diseases》2004,48(4):902-908

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Expression of drought responsive genes in pigeonpea and in silico comparison with soybean cDNA library     

Nagaraja Deeplanaik  Ramesh Chapeyil Kumaran  Krishna Venkatarangaiah  Santosh Kumar Hulikal Shivashankar  Dadakhalandar Doddamani  Sandeep Telkar 《Journal of Crop Science and Biotechnology》2013,16(4):243-251

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Evaluation of a high-throughput nucleic acid extraction method for the detection of Mycobacterium avium subsp. paratuberculosis in bovine fecal samples by PCR     

Nagaraja R. Thirumalapura  Willard Feria  Eric Hue  Corey Zellers  Deepanker Tewari 《Journal of veterinary diagnostic investigation》2021,33(2):375

Johne’s disease (paratuberculosis) is an economically important disease of cattle worldwide. The disease is caused by Mycobacterium avium subsp. paratuberculosis (MAP), a fastidious gram-positive bacterium. PCR is increasingly used in diagnostic laboratories for the detection of MAP in fecal samples given the rapid test turnaround time and sensitivity and specificity comparable to fecal culture. However, efficient extraction of DNA for sensitive detection of MAP by PCR is affected by the complex lipid-rich cell wall of MAP and the presence of PCR inhibitors in feces. We evaluated a high-throughput nucleic acid extraction method (MagMAX core nucleic acid purification kit with mechanical lysis module) in conjunction with an hspX gene PCR for the detection of MAP from bovine fecal samples, which resulted in correct identification of all negative (13 of 13) and positive (35 of 35) proficiency test samples obtained from the National Veterinary Services Laboratories. In addition, all 6 negative and 50 of 51 positive diagnostic specimens tested were categorized correctly.  相似文献   

Estimating the level of disease risk and biosecurity on commercial poultry farms in New Zealand     

SS Greening  K Mulqueen  TG Rawdon  NP French  MC Gates 《New Zealand veterinary journal》2020,68(5):261-271

ABSTRACT

Aims: To collect baseline data on the contact risk pathways and biosecurity practices of commercial poultry farms in New Zealand, investigate the relationship between the farm-level disease contact risks and biosecurity practices, and identify important poultry health concerns of producers.

Methods: A cross-sectional survey of all registered New Zealand commercial poultry operations was conducted in 2016 collecting information on farm demographics, biosecurity practices, and contact risk pathways. Survey responses were used to generate an unweighted subjective disease risk score based on eight risk criteria and a subjective biosecurity score based on the frequency with which producers reported implementing seven biosecurity measures. Producer opinions towards poultry health issues were also determined.

Results: Responses to the survey response were obtained from 120/414 (29.0%) producers, including 57/157 (36.3%) broiler, 33/169 (19.5%) layer, 24/55 (44%) breeder, and 6/32 (19%) other poultry production types. Median disease risk scores differed between production types (p?<?0.001) and were lowest for breeder enterprises. The greatest risk for layer and broiler enterprises was from the potential movement of employees between sheds, and for breeder enterprises was the on- and off-farm movement of goods and services. Median biosecurity scores also differed between production types (p?<?0.001), and were highest for breeder and broiler enterprises. Across all sectors there was no statistical correlation between biosecurity scores and disease risk scores. Producers showed a high level of concern over effectively managing biosecurity measures.

Conclusions: The uptake of biosecurity measures in the commercial poultry farms surveyed was highly variable, with some having very low scores despite significant potential disease contact risks. This may be related to the low prevalence or absence of many important infectious poultry diseases in New Zealand leading farmers to believe there is a limited need to maintain good biosecurity as well as farmer uncertainty around the efficacy of different biosecurity measures. Further research is needed to understand barriers towards biosecurity adoption including evaluating the cost-effectiveness of biosecurity interventions.  相似文献   

Effects of feeding wet corn distillers grains with solubles with or without monensin and tylosin on the prevalence and antimicrobial susceptibilities of fecal foodborne pathogenic and commensal bacteria in feedlot cattle     

Jacob ME  Fox JT  Narayanan SK  Drouillard JS  Renter DG  Nagaraja TG 《Journal of animal science》2008,86(5):1182-1190

Distillers grains, a coproduct of ethanol production from cereal grains, are composed principally of the bran, protein, and germ fractions and are commonly supplemented in ruminant diets. The objective of this study was to assess the effect of feeding wet distillers grains with solubles (WDGS) and monensin and tylosin on the prevalence and antimicrobial susceptibilities of fecal foodborne and commensal bacteria in feedlot cattle. Cattle were fed 0 or 25% WDGS in steam-flaked corn-based diets with the addition of no antimicrobials, monensin, or monensin and tylosin. Fecal samples were collected from each animal (n = 370) on d 122 and 136 of the 150-d finishing period and cultured for Escherichia coli O157. Fecal samples were also pooled by pen (n = 54) and cultured for E. coli O157, Salmonella, commensal E. coli, and Enterococcus species. Antimicrobial resistance was assessed by determining antimicrobial susceptibilities of pen bacterial isolates and quantifying antimicrobial resistance genes in fecal samples by real-time PCR. Individual animal prevalence of E. coli O157 in feces collected from cattle fed WDGS was greater (P < 0.001) compared with cattle not fed WDGS on d 122 but not on d 136. There were no treatment effects on the prevalence of E. coli O157 or Salmonella spp. in pooled fecal samples. Antimicrobial susceptibility results showed Enterococcus isolates from cattle fed monensin or monensin and tylosin had greater levels of resistance toward macrolides (P = 0.01). There was no effect of diet or antimicrobials on concentrations of 2 antimicrobial resistance genes, ermB or tetM, in fecal samples. Results from this study indicate that WDGS may have an effect on the prevalence of E. coli O157 and the concentration of selected antimicrobial resistance genes, but does not appear to affect antimicrobial susceptibility patterns in Enterococcus and generic E. coli isolates.  相似文献