1
|
Harper SJ, Cowell SJ, Dawson WO. Bottlenecks and complementation in the aphid transmission of citrus tristeza virus populations. Arch Virol 2018; 163:3373-3376. [PMID: 30191371 DOI: 10.1007/s00705-018-4009-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 08/22/2018] [Indexed: 11/28/2022]
Abstract
Aphid transmission is a major factor in the formation of citrus tristeza virus (CTV) populations. Here, we examined the effect of population interaction on aphid transmissibility of different CTV genotypes. We found that there was no correlation between the proportion of viral genotypes in the source population and what was transmitted. We next examined the transmission of a poorly transmitted infectious cDNA clone (T36) in mixture with other CTV genotypes. T36 transmission increased from 0.5% alone, to up to 35.7%, depending on the coinfecting genotype. These results suggest that interaction between CTV genotypes affects the transmission of this virus.
Collapse
Affiliation(s)
- S J Harper
- Department of Plant Pathology, Washington State University, Prosser, WA, USA.
| | - S J Cowell
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL, USA
| | - W O Dawson
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL, USA
| |
Collapse
|
2
|
Harper SJ, Cowell SJ, Dawson WO. Isolate fitness and tissue-tropism determine superinfection success. Virology 2017; 511:222-228. [PMID: 28888112 DOI: 10.1016/j.virol.2017.08.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 08/24/2017] [Accepted: 08/26/2017] [Indexed: 01/07/2023]
Abstract
The mechanism of cross-protection, the deliberate infection of plants with a "mild" virus isolate to protect against "severe" isolates, has long been a topic of debate. In our model system, Citrus tristeza virus (CTV), this appears to be genotype-specific superinfection-exclusion, suggesting a simple recipe for cross-protection. However, this concept failed in field trials, which led us to examine the process of superinfection-exclusion more closely. We found that exclusion relies on the relative fitness of the primary versus the challenge isolates, and the host infected, and that significant differences in superinfection success could occur between isolates that differ by as few as 3 nucleotides. Furthermore, we found that exclusion was not uniform throughout the plant, but was tissue-specific. These data suggest that cross-protection is not a simple like-for-like process but a complex interaction between the primary and challenge isolates and the host.
Collapse
Affiliation(s)
- S J Harper
- Department of Plant Pathology, Washington State University, Prosser, WA 99350, USA.
| | - S J Cowell
- Department of Plant Pathology, Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, USA
| | - W O Dawson
- Department of Plant Pathology, Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, USA
| |
Collapse
|
3
|
Harper SJ, Killiny N, Tatineni S, Gowda S, Cowell SJ, Shilts T, Dawson WO. Sequence variation in two genes determines the efficacy of transmission of citrus tristeza virus by the brown citrus aphid. Arch Virol 2016; 161:3555-3559. [PMID: 27644950 DOI: 10.1007/s00705-016-3070-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 09/15/2016] [Indexed: 10/21/2022]
Abstract
Vector transmission is an important part of the viral infection cycle, yet for many viruses little is known about this process, or how viral sequence variation affects transmission efficacy. Here we examined the effect of substituting genes from the highly transmissible FS577 isolate of citrus tristeza virus (CTV) in to the poorly transmissible T36-based infectious clone. We found that introducing p65 or p61 sequences from FS577 significantly increased transmission efficacy. Interestingly, replacement of both genes produced a greater increase than either gene alone, suggesting that CTV transmission requires the concerted action of co-evolved p65 and p61 proteins.
Collapse
Affiliation(s)
- S J Harper
- Department of Plant Pathology, University of Florida, 700 Experiment Station Road, Lake Alfred, Florida, 33850, USA.
| | - N Killiny
- Department of Plant Pathology, University of Florida, 700 Experiment Station Road, Lake Alfred, Florida, 33850, USA
| | - S Tatineni
- U.S. Department of Agriculture, Agricultural Research Service, and Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - S Gowda
- Department of Plant Pathology, University of Florida, 700 Experiment Station Road, Lake Alfred, Florida, 33850, USA
| | - S J Cowell
- Department of Plant Pathology, University of Florida, 700 Experiment Station Road, Lake Alfred, Florida, 33850, USA
| | - T Shilts
- Department of Plant Pathology, University of Florida, 700 Experiment Station Road, Lake Alfred, Florida, 33850, USA
| | - W O Dawson
- Department of Plant Pathology, University of Florida, 700 Experiment Station Road, Lake Alfred, Florida, 33850, USA
| |
Collapse
|
4
|
Harper SJ, Cowell SJ, Dawson WO. With a little help from my friends: complementation as a survival strategy for viruses in a long-lived host system. Virology 2015; 478:123-8. [PMID: 25666523 DOI: 10.1016/j.virol.2014.12.041] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 12/07/2014] [Accepted: 12/20/2014] [Indexed: 11/16/2022]
Abstract
In selective host species, the extent of Citrus tristeza virus (CTV) infection is limited through the prevention of long-distance movement. As CTV infections often contain a population of multiple strains, we investigated whether the members of a population were capable of interaction, and what effect this would have on the infection process. We found that the tissue-tropism limitations of strain T36 in selective hosts could be overcome through interaction with a second strain, VT, increasing titer of, and number of cells infected by, T36. This interaction was strain-specific: other strains, T30 and T68, did not complement T36, indicating a requirement for compatibility between gene-products of the strains involved. This interaction was also host-specific, suggesting a second requirement of compatibility between the provided gene-product and host. These findings provide insight into the 'rules' that govern interaction between strains, and suggest an important mechanism by which viruses survive in a changing environment.
Collapse
Affiliation(s)
- S J Harper
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL, USA.
| | - S J Cowell
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL, USA
| | - W O Dawson
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL, USA
| |
Collapse
|
5
|
|
6
|
|
7
|
|
8
|
|
9
|
Affiliation(s)
- S J Cowell
- St Thomas's Hospital Medical School and the Medical Unit, University College Hospital, London
| |
Collapse
|
10
|
Affiliation(s)
- S J Cowell
- The Medical School, St Thomas's Hospital, London
| |
Collapse
|
11
|
Abstract
Aortic stenosis is the most common adult heart valve condition seen in the Western world and its incidence continues to rise. No established disease modifying treatments retard progression of the stenotic process. Recent insights into the pathogenesis of calcific aortic stenosis suggest that the disease mimics atherosclerosis. The natural history and progression of calcific aortic stenosis are described with particular emphasis on new and emerging medical treatments that may modify the disease process. In particular, statins and angiotensin converting enzyme inhibitors appear to hold promise but definitive evidence from large clinical trials is awaited.
Collapse
Affiliation(s)
- D E Newby
- Department of Cardiology, Royal Infirmary, Edinburgh, UK.
| | | | | |
Collapse
|
12
|
Houslay ES, Cowell SJ, Prescott RJ, Reid J, Burton J, Northridge DB, Boon NA, Newby DE. Progressive coronary calcification despite intensive lipid-lowering treatment: a randomised controlled trial. Heart 2006; 92:1207-12. [PMID: 16449511 PMCID: PMC1861190 DOI: 10.1136/hrt.2005.080929] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
OBJECTIVES To evaluate the effect of intensive lipid-lowering treatment on coronary artery calcification in a substudy of a trial recruiting patients with calcific aortic stenosis. METHODS In a double blind randomised controlled trial, 102 patients with calcific aortic stenosis and coronary artery calcification were randomly assigned by the minimisation technique to atorvastatin 80 mg daily or matched placebo. Coronary artery calcification was assessed annually by helical computed tomography. RESULTS 48 patients were randomly assigned to atorvastatin and 54 to placebo with a median follow up of 24 months (interquartile range 24-30). Baseline characteristics and coronary artery calcium scores were similar in both groups. Atorvastatin reduced serum low density lipoprotein cholesterol (-53%, p < 0.001) and C reactive protein (-49%, p < 0.001) concentrations whereas there was no change with placebo (-7% and 17%, p > 0.95 for both). The rate of change in coronary artery calcification was 26%/year (0.234 (SE 0.037) log arbitrary units (AU)/year; n = 39) in the atorvastatin group and 18%/year (0.167 (SE 0.034) log AU/year; n = 49) in the placebo group, with a geometric mean difference of 7%/year (95% confidence interval -3% to 18%, p = 0.18). Serum low density lipoprotein concentrations were not correlated with the rate of progression of coronary calcification (r = 0.05, p = 0.62). CONCLUSION In contrast to previous observational studies, this randomised controlled trial has shown that, despite reducing systemic inflammation and halving serum low density lipoprotein cholesterol concentrations, statin treatment does not have a major effect on the rate of progression of coronary artery calcification.
Collapse
Affiliation(s)
- E S Houslay
- Department of Cardiology, Royal Infirmary, Edinburgh, UK
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Cowell SJ, Newby DE, Burton J, White A, Northridge DB, Boon NA, Reid J. Aortic valve calcification on computed tomography predicts the severity of aortic stenosis. Clin Radiol 2003; 58:712-6. [PMID: 12943644 DOI: 10.1016/s0009-9260(03)00184-3] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM Incidental aortic valve calcification is often detected during computed tomography. The aim was to compare the severity of valvular stenosis and calcification in patients with aortic stenosis. MATERIALS AND METHODS One hundred and fifty-seven patients aged 68+/-11 years (range: 34-85) with aortic valve stenosis underwent multislice helical computed tomography and Doppler echocardiography performed by independent, blinded observers. The aortic valve calcium score was determined using automated computer software calibrated with a phantom. RESULTS Doppler echocardiography demonstrated a post-valve velocity of 3.45+/-0.66 m/s and a peak gradient of 49+/-11 mmHg. Computed tomography showed excellent reproducibility and the median aortic valve calcium score was 5858 AU (interquartile range, 1555-14,596). The computed tomography aortic valve calcium score positively correlated with the Doppler post-valve velocity and peak gradient (r=0.54, p<0.0001 for both) of the aortic valve. All patients with severe aortic stenosis had a calcium score of >3700 AU. CONCLUSION Calcification of the aortic valve is closely associated with the severity of aortic stenosis, and heavy calcification suggests the presence of severe aortic stenosis that requires urgent cardiological assessment. Patients with lesser degrees of aortic valve calcification should be screened for aortic stenosis and monitored for disease progression.
Collapse
Affiliation(s)
- S J Cowell
- Department of Cardiology, Royal Infirmary, Edinburgh, Scotland, UK.
| | | | | | | | | | | | | |
Collapse
|
14
|
|
15
|
Cowell SJ. RECENT RESEARCH ON VITAMINS. West J Med 1956. [DOI: 10.1136/bmj.1.4965.498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
16
|
|
17
|
Cowell SJ. The Training of Dieticians: The Current Position. Proc Nutr Soc 1946; 4:259-62. [DOI: 10.1079/pns19460052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
18
|
Cowell SJ. Physiological Bases of Nutrition. West J Med 1937; 2:406-9. [DOI: 10.1136/bmj.2.3999.406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|