Cross-neutralization of genetic reassortants of bluetongue virus serotypes 20 and 21

Genetic reassortment studies of bluetongue virus (BTV) Types 20 and 21 have revealed a reassortant genotype that was not neutralized serotype-specifically. In reciprocal neutralization tests, BTV 20 and 21 were neutralized specifically by homologous antiserum. Similarly, reassortants that possessed both outer capsid proteins (i.e., VP2 and VP5) from the same parent virus reacted with that antiserum specifically. However, two reassortants, 16(9) and 19(1), with VP2 of BTV 20 and VP5 of BTV 21 had intermediate neutralization characteristics. These reassortants were neutralized to high titres by antiserum to BTV 20 and to lower, but significant titres by antiserum to BTV 21. In addition, antiserum to BTV 20 induced 10-16-fold higher titres in plaque reduction neutralization (PRN) tests with these two reassortants compared with BTV 20 itself. Evidence of the serological cross-reactivity of Reassortants 16(9) and 19(1) was also found with respect to reductions in plaque sizes observed in the PRN tests. The average plaque sizes of these reassortants were reduced to differing extents by antiserum to BTV 20 and 21, while those formed by the parent viruses were reduced in size by homologous antiserum only. Immunoblotting analysis of the structural proteins of BTV 20 and 21 demonstrated that VP2 alone was antigenically distinct, therefore confirming its role in determining serotype specificity in virus-neutralization tests. Electrophoretic analysis revealed considerable migrational differences between VP2 and VP5 of the parent viruses, suggesting that there was some divergence in their molecular weights, intrinsic charges or structural compositions. Taken together, the data suggest that the intermediate neutralization characteristics of the reassortants that contain VP2 and VP5 from different parent viruses are due to conformational alterations in their outer capsid structure which allow antibody recognition of common neutralizing epitopes that are not exposed on BTV 20 or BTV 21.     

Lumbar epidural chondrosarcoma in a dog treated by excision and chemotherapy

A 5-year-old dog developed neurologic signs of thoracolumbar spinal cord dysfunction. The presence of an epidural mass which affected the electromyogram of the T-13 to L-3 spinal segments was demonstrated by myelography. Surgical removal was attempted. Examination of frozen and formalin-fixed tissues revealed the mass to be a chondrosarcoma. Doxorubicin hydrochloride was given every third week for a total of 6 doses following surgery. No signs of recurrence or metastases have been found for over 6 months. The differential diagnosis of epidural masses should include chondrosarcoma, even in the absence of vertebral lesions on plain radiographs, as in this case. Rapid diagnosis and aggressive therapy may have improved the prognosis.     

Ultrasound diagnosis: intra-abdominal torsion of a non-neoplastic testicle in a cryptorchid dog

A 6-month-old male bilaterally cryptorchid Boxer was examined for acute abdominal pain. The results of physical examination, laboratory testing, and ultrasonographic examination are presented. Intra-abdominal testicular torsion was suspected and confirmed at surgery. No evidence of neoplasia was found at histopathologic examination of the twisted testicle. A discussion of testicular torsion is presented.     

English field samples of Thrips tabaci show strong and ubiquitous resistance to deltamethrin

BACKGROUND: Onion thrips, Thrips tabaci Lindeman, is a prevalent pest of glasshouse and field vegetables, such as leeks and salad onions. Pesticides are the main option for control, but this approach risks the evolution and spread of insecticide resistance. In the light of anecdotal reports in the United Kingdom of poor efficacy of pyrethroids against T. tabaci, thought to be primarily a consequence of resistance, the responses to deltamethrin of ten English samples of T. tabaci, collected from field leeks and salad onions in 2006, were measured to establish the level and prevalence of potential resistance to this compound. RESULTS: All the samples showed significant deltamethrin resistance that was comparable or slightly lower than the maximum level reported previously for T. tabaci from New Zealand. CONCLUSION: The mechanism(s) conferring deltamethrin resistance remain unknown at present but are likely to extend to other synthetic pyrethroids approved for use against this species. The findings suggest that these compounds are unlikely to give satisfactory control of T. tabaci in England and have stimulated the recommendation to use alternatives. Copyright © 2010 Society of Chemical Industry     

Age-specific expression of resistance to a neonicotinoid insecticide in the whitefly Bemisia tabaci

Neonicotinoid insecticides retain a crucial role within many chemical and integrated control strategies for the tobacco whitefly, Bemisia tabaci Gennadius, in spite of the establishment of potent and widespread resistance in many areas. Metabolic resistance mechanisms mediated by overexpression of P450-dependent monooxygenases have been implicated in neonicotinoid resistance in the two most prevalent B. tabaci biotypes. Further characterisation of resistance to the neonicotinoid imidacloprid in populations of both these B- and Q-types is reported.Expression of resistance to imidacloprid was age specific in B- and Q-type strains of B. tabaci. The highest observed resistance ratio at LC(50) expressed in prepupal nymphs was 13, compared with at least 580 in their adult counterparts. For all strains, resistance expressed in immatures was not sufficiently potent to compromise recommended imidacloprid application rates.Targeting neonicotinoids towards immature life stages of B. tabaci may circumvent the protection conferred by current mechanisms of resistance, simultaneously reducing the selection pressures imposed. However, such tactics may enhance the expression of existing resistance mechanisms in immatures, or promote the establishment of novel ones expressed in all life stages.     

High-throughput allelic discrimination of B and Q biotypes of the whitefly, Bemisia tabaci, using TaqMan allele-selective PCR

BACKGROUND: B and Q biotypes of the whitefly, Bemisia tabaci (Gennadius), are generally regarded as the most significant given their global distribution and strong resistance to insecticides. Since these biotypes can coexist and differ markedly in their insecticide resistance profiles, a rapid but reliable means of discriminating between them would be a valuable complement to resistance monitoring and management programmes. Recently, PCR‐based methods have been developed to determine the biotype status of B. tabaci populations. However, these require post‐amplification procedures, which increase time and labour. RESULTS: The authors have developed an allelic discrimination real‐time PCR assay using fluorescent dye‐labelled probes to distinguish the B and Q biotypes. The assay targets a single nucleotide polymorphism (SNP) in the mitochondrial cytochrome oxidase I (mtCOI) gene. To evaluate the assay, DNA was extracted from individual whiteflies of six known biotype strains, and all scored correctly as either a B or Q biotype. As further validation, 72 individuals from field samples collected in different parts of the world were also tested by the assay. No failed reactions were observed, with all 72 samples scoring clearly as either the B or Q biotype. CONCLUSION: The development of this rapid and high‐throughput assay has important potential for routine monitoring of B and Q biotypes on ornamental plants and for the screening of B. tabaci populations in countries where these biotypes are not yet established. Copyright © 2007 Society of Chemical Industry     

Effects of acute fasting and age on leptin and peroxisome proliferator‐activated receptor gamma production relative to fat depot in immature and mature pigs

Leptin and peroxisome proliferator‐activated receptor gamma (PPARγ) are adipogenic proteins that are actively involved in metabolic homeostasis of fat. Recently, it was reported that fat tissue in humans and rodents differs in metabolic activity relative to anatomical location of the fat tissue (i.e. depots) and animal age. Hence, we hypothesized that leptin and PPARγ production in various fat depots in female pigs differs in response to acute fasting, and that these responses vary with physiological maturity of the animal. Sixteen intact crossbred immature female pigs [prepubertal (PP); 132.2 ± 4.1 days] and 16 sexually mature female pigs (M; 224 ± 7.4 days) housed in an open‐air, concrete slab, sheltered barn were randomly assigned to either Control or Fasted treatments. Control pigs (PP, n = 8; M, n = 8) had ad libitum access to feed, while Fasted pigs (PP, n = 8; M, n = 8) were denied access to feed from the onset of the study (0 h) to euthanasia at 72 h. Immediately post‐mortem, fat samples were collected from the subcutaneous, pelvic, kidney, and heart (M pigs only) fat depots and analysed for leptin and PPARγ mRNA and protein content. Acute fasting decreased mean leptin mRNA tissue content in a depot specific manner in M pigs (p < 0.01), while mean leptin protein concentrations in fat tissues did not differ with fat depot or age of the pig. Furthermore, acute fasting did not affect mean PPARγ mRNA tissue content in a fat depot or age dependent manner. Mean concentrations of PPARγ protein in fat depots tended to be greater in M vs. PP pigs (p = 0.07). We suggest that these data provide evidence that acute fasting has a greater effect on leptin than PPARγ production in a fat depot dependent manner in M pigs, which may be indicative of changing physiological demands as an animal matures.     

Comparison of Short‐ and Long‐term Function and Radiographic Osteoarthrosis in Dogs After Postoperative Physical Rehabilitation and Tibial Plateau Leveling Osteotomy or Lateral Fabellar Suture Stabilization

Objectives— To compare short‐ and long‐term functional and radiographic outcome of cranial cruciate ligament (CrCL) injury in dogs treated with postoperative physical rehabilitation and either tibial plateau leveling osteotomy (TPLO) or lateral fabellar suture stabilization (LFS). Study Design— Prospective observational clinical study. Animals— Medium to large breed dogs with naturally occurring CrCL injury (n=65). Methods— Dogs with CrCL injury were treated with either TPLO or LFS and with identical physical rehabilitation regimes postoperatively. Limb peak vertical force (PVF) was measured preoperatively and at 3, 5, and 7 weeks, and 6 months and 24 months postoperatively. Stifles were radiographically assessed for osteoarthrosis (OA) preoperatively and 24 months postoperatively. Results— Thirty‐five dogs had LFS and 30 dogs had TPLO. Radiographic OA scores were significantly increased at 24 months compared with preoperative scores in all dogs. Radiographic OA scores preoperatively and at 24 months were not significantly different between treatment groups. PVF was significantly increased from preoperative to 24 months among both treatment groups but not significantly different between treatment groups preoperatively or at 3, 5, 7 weeks, 6, or 24 months. Conclusion— No significant difference in outcome as determined by ground reaction forces or radiographic OA scores were found between dogs with CrCL injury treated with LFS or TPLO. Clinical Relevance— LFS and TPLO remain good options for stabilizing stifles with CrCL injury with all dogs showing significant functional improvement. This study does not support the superiority of either surgical technique.     

Biotype Q of<Emphasis Type="Italic">Bemisia tabaci</Emphasis> identified in Israel

The biotype status of samples of the whiteflyBemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) collected from several field and greenhouse sites in Israel during 1999–2000 was determined by polyacrylamide gel electrophoresis (PAGE) for general esterases, and by RAPD-PCR using primers of arbitrary sequence. Results of this survey provide the first published evidence for the occurrence of theB. tabaci Q biotype, alongside the more widely distributed B biotype. Based on the collected samples, it appears that both the B and Q biotypes are present in Israel, and that field populations consist of a mixture of the two biotypes. A possible link betweenB. tabaci biotypes and insecticide resistance is discussed. Contribution no. 508/02 from the Inst. of Plant Protection, ARO, The Volcani Center, Bet Dagan, Israel. http://www.phytoparasitica.org posting Dec. 5, 2002.