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Mixed Infections (mixed + infections)

Distribution by Scientific Domains

Life Sciences	68%
Medical Sciences	31%

Selected Abstracts

VIRULENCE AND COMPETITIVENESS: TESTING THE RELATIONSHIP DURING INTER- AND INTRASPECIFIC MIXED INFECTIONS

EVOLUTION, Issue 9 2010
Peter A. Staves
Understanding the reasons why different parasites cause different degrees of harm to their hosts is an important objective in evolutionary biology. One group of models predicts that if hosts are infected with more than one strain or species of parasite, then competition between the parasites will select for higher virulence. While this idea makes intuitive sense, empirical data to support it are rare and equivocal. We investigated the relationship between fitness and virulence during both inter- and intraspecific competition for a fungal parasite of insects, Metarhizium anisopliae. Contrary to theoretical expectations, competition favored parasite strains with either a lower or a higher virulence depending on the competitor: when in interspecific competition with an entomopathogenic nematode, Steinernema feltiae, less virulent strains of the fungus were more successful, but when competing against conspecific fungi, more virulent strains were better competitors. We suggest that the nature of competition (direct via toxin production when competing against the nematode, indirect via exploitation of the host when competing against conspecific fungal strains) determines the relationship between virulence and competitive ability. [source]

Analysis of mixed infections by multiple genotypes of human cytomegalovirus in immunocompromised patients

JOURNAL OF MEDICAL VIROLOGY, Issue 5 2009
P. Sowmya
Abstract Human cytomegalovirus (HCMV) is a significant cause of morbidity and mortality in immunocompromised patients. The present study was carried out to determine the frequency of occurrence of multiple genotypes of HCMV in immunocompromised patients, to determine if there is any discrepancy in identification of mixed infections by multiple genotypes in paired clinical specimens obtained from patients and to determine the significance of viral load differences between patients infected with single and multiple genotypes. One hundred clinical specimens from 75 patients were included in the study. Real-time PCR; Multiplex PCR and PCR-based RFLP were applied for the determination of viral load and genotyping of HCMV, respectively. Out of the 75 patients, 36 (48%) carried multiple genotypes. Discrepancy with regard to detection of genotypes were found in 17/25 patients whose paired clinical specimens were analyzed. Mixed genotypes were found more often in peripheral blood than urine or intraocular fluids collected from the same patient. There was a statistically significant difference between the median viral loads of clinical specimens carrying single genotypes and multiple genotypes. Mixed infections with multiple genotypes were found predominantly in the leukocyte fraction of peripheral blood specimens. The detection of mixed infections by multiple genotypes in the hypervariable regions of HCMV can be a surrogate marker of an increase in viral load. J. Med. Virol. 81:861,869, 2009. © 2009 Wiley-Liss, Inc. [source]

Competitive interactions and persistence of two nematode species that parasitize Drosophila recens

ECOLOGY LETTERS, Issue 6 2001
S.J. Perlman
Drosophila recens is parasitized in the wild by two nematodes, Howardula aoronymphium, a host generalist, and Parasitylenchus nearcticus, a host specialist known only from D. recens. In order to understand how these two parasite species coexist, we compared their ability to infect and grow in D. recens, their effects on host fecundity and survival, and whether one parasite species was competitively superior in double infections. The specialist nematode P. nearcticus had greater rates of infection and reproduction than the generalist H. aoronymphium, and completely sterilized females in single and mixed infections. The specialist was competitively superior in mixed infections, as generalist motherworms were significantly smaller than in single infections. These results suggest that P. nearcticus might competitively exclude H. aoronymphium if D. recens were the only host available. It is likely that H. aoronymphium persists in D. recens by transmission from other, more suitable host species. [source]

Persistence of Cryphonectria hypoviruses after their release for biological control of chestnut blight in West Virginia forests

FOREST PATHOLOGY, Issue 6 2002
Y.-C. Liu
Summary Although Cryphonectria hypoviruses have been relatively successful as biological control agents of chestnut blight in Europe, their success in North America has been limited. Experimental releases of hypoviruses were made in 1978,82 at two sites in West Virginia forests with high densities of regenerating chestnut trees. Cryphonectria hypovirus 1 (CHV-1) from Europe, as well as American isolates of Cryphonectria parasitica containing CHV-3, were used for these releases. Although most trees died during the 5-year release period, it was not known if the hypoviruses persisted in the C. parasitica population at the two sites. When the experimental plots were revisited in 1994, few chestnut trees were found. The exception was one plot containing coppice sprouts that had grown from the root collars of the original trees. The authors intensively sampled C. parasitica from experimental plots and screened recovered isolates for double-stranded RNA (dsRNA). None of the isolates contained CHV-1; only six isolates contained CHV-3, all from the plots with the coppice sprouts. CHV-4, which occurs naturally in West Virginia forests and in two released isolates, hybridized to dsRNA from the isolates containing CHV-3, indicating mixed infections. CHV-4 also hybridized to dsRNA from other isolates sampled inside and outside the treated plots. In contrast to CHV-1 and CHV-3, however, CHV-4 has little effect on the growth or phenotype of C. parasitica. The limited persistence of CHV-1 and CHV-3 may have resulted when the C. parasitica population was reduced in size due to the failure of chestnut trees to resprout because of competition from other hardwood species. Résumé Bien que les hypovirus de Cryphonectria aient remporté un réel succès comme agents de lutte biologique contre le chancre du châtaignier en Europe, leur succès en Amérique du nord a été limité. Des applications d'hypovirus ont été faites en 1978,1982 en Virginie de l'ouest dans deux sites forestiers à fortes densités de régénérations de châtaigniers. Le CHV-1 originaire d'Europe ainsi que des isolats américains contenant le CHV-3 ont été utilisés dans ces essais. Bien que la plupart des arbres soient morts pendant les cinq ans de l'application, on ne sait pas si les hypovirus ont persisté dans la population de Cryphonectria parasitica. Quand les parcelles expérimentales ont été revisitées en 1994, peu de châtaigniers ont été trouvés. Un site faisait exception qui était un taillis de rejets issu de racines de souches. Nous avons échantillonné intensivement le C. parasitica dans les placettes et le dsRNA a été examiné dans les isolats obtenus. Parmi tous les isolats provenant des placettes de taillis, aucun ne contenait CHV-1 et seulement six contenaient CHV-3. CHV-4 qui existe naturellement dans les forêts en Virginie de l'ouest et dans deux des isolats appliqués, s'hybridait avec le dsRNA d'autres isolats contenant CHV-3, ce qui indique des infections mixtes. CHV-4 s'hybridait aussi avec le dsRNA d'autres isolats recueillis dans ou au dehors des placettes traitées. Contrairement à CHV1 et à CHV-3, CHV-4 a cependant peu d'effet sur la croissance et le phénotype de C. parasitica. La persistance limitée de CHV-1 et de CHV-3 peut avoir résulté de la réduction de la population de C. parasitica par un manque de rejets de châtaigniers dûà la compétition avec les autres espèces de feuillus. Zusammenfassung Währenddem der Einsatz von Cryphonectria Hypoviren zur biologischen Bekämpfung des Kastanienrindenkrebses in Europa relativ erfolgreich war, stimmt dies in Nordamerika nur begrenzt. In West-Virginia wurden in den Jahren 1978,82 Hypoviren in Experimenten an zwei Waldstandorten mit hoher Dichte regenerierender Edelkastanien freigesetzt. Cryphonectria hypovirus 1 (CHV-1) von Europa und amerikanische Isolate von Cryphonectria parasitica, die CHV-3 enthielten, wurden für diese Freisetzungsversuche verwendet. Obschon die meisten Bäume während der fünfjährigen Freisetzungsperiode abstarben, war unklar, ob die Hypoviren in der C. parasitica Population überlebten. Als die Versuchsflächen im Jahre 1994 erneut aufgesucht wurden, konnten nur noch wenige Edelkastanien gefunden werden mit Ausnahme einer Fläche, auf der die Wurzelanläufe ursprünglicher Bäume Stockausschläge trugen. Zahlreiche C. parasitica Stämme wurden von den Versuchsflächen gewonnen und auf Besiedlung mit dsRNA untersucht. Keines der Isolate enthielt CHV-1; nur sechs Isolate, welche alle von der Fläche mit den Stockausschlägen stammten, enthielten CHV-3. CHV-4, das natürlich in den Wäldern West-Viriginias vorkommt und in zwei der freigesetzten Isolate vorhanden war, hybridisierte mit dsRNA aus den Isolaten, die CHV-3 enthielten, was auf eine Mischinfektion hindeutet. CHV-4 hybridisierte auch mit dsRNA aus anderen Isolaten, die innerhalb und ausserhalb der behandelten Versuchsflächen gesammelt wurden. Im Gegensatz zu CHV-1 und CHV-3 war der Einfluss von CHV-4 auf den Phänotyp von C. parasitica gering. Die begrenzte Persistenz von CHV-1 und CHV-3 wird möglicherweise durch die Abnahme der C. parasitica Population als Folge des Ausbleibens der Regeneration der Edelkastanie bedingt. Erschwerend für die Edelkastanien dürfte sich zudem die Konkurrenz mit anderen Laubhölzern auswirken. [source]

Evidence of occult HCV genotypes in haemophilic individuals with unapparent HCV mixed infections

HAEMOPHILIA, Issue 4 2008
C. PARODI
Summary., Individuals with haemophilia who received non heat-treated factor concentrates were likely to undergo multiple exposures to the hepatitis C virus (HCV). Therefore, HCV mixed-genotype infections might be more frequent in these patients than in the general population. Their prevalence is extremely variable in similar groups of patients tested by different assays due to the fact that currently available genotyping techniques are not suitable to detect multiple HCV genotypes in a viral population. As an HCV viral reservoir, the peripheral blood mononuclear cell (PBMC) might harbor viral variants distinct from the genotypes detected in plasma. We investigated the presence of HCV genotypes in a group of chronically infected haemophilic patients in the PBMC compartment using a non-stimulated cell culture system that allows the detection of the HCV genome in culture supernatants. We compared them to the HCV genotypes found in plasma samples. Cell culture experiments performed with PBMC demonstrated the presence of additional HCV genotypes that were undetected in the corresponding plasma samples with the same genotyping technique. Although mixed infections at HCV genotype level became evident in 5.6% of the patients (16/288), the culture methodology increased the number of HCV infections with multiple genotypes to 62.5% (10/16) (P < 0.0001). Once more, the role of mononuclear cells as HCV viral reservoirs is emphasized. Considering minor strains could influence the outcome of treatment, detection of covert HCV mixed-genotype infections might be essential for choosing the adequate therapeutic regimen. [source]

Cocirculation of and coinfections with hepatitis A virus subgenotypes IIIA and IB in patients from Pune, western India

HEPATOLOGY RESEARCH, Issue 2 2007
Shobha Chitambar
Aim:, During the 1990s, a changing pattern of epidemiology of hepatitis A was reported in different populations of India. The present study was undertaken to investigate the molecular epidemiology of hepatitis A virus (HAV) strains over a period of 10 years. Methods:, Stool/serum samples were collected from hepatitis A patients clinically presenting acute viral hepatitis and hepatic encephalopathy. Reverse transcriptase polymerase chain reaction (RT-PCR) was performed to detect HAV-RNA. HAV genomes were examined by sequencing PCR products of VP1/2A junction (168 bp) and RNA polymerase (116 bp) regions. Results:, Subgenotype IIIA and IB were detected in 74.2% and 9.7% of specimens, respectively, while 16.1% of patients had mixed infections. Sewage samples also showed presence of both IIIA (9/10) and IB (1/10) subgenotypes. RNA polymerase region showed two clusters constituting 51.6% and 19.4% strains closer to Nor21 and HM175 strains, respectively, in clinical specimens. Three isolates appeared as discordant subgenotypes in VP1/2A and RNA polymerase regions. Conclusion:, The data revealed cocirculation of and coinfection with subgenotypes IIIA and IB, with predominance of IIIA and genetic heterogeneity of HAV strains in western India. [source]

Antimicrobial therapy in Dermatology

JOURNAL DER DEUTSCHEN DERMATOLOGISCHEN GESELLSCHAFT, Issue 1 2006
Cord Sunderkötter
Antiseptika; Antibiotika; ,-Laktam-Resistenz; Weichteilinfektion Summary The extensive and sometimes indiscriminate use of antibiotics sometimes without strict indications has led to increases in both bacterial resistance and sensitization of patients. Systemic antibiotics in skin infections are indicated when a severe local infection occurs which spreads into the surrounding tissue or when there are signs of systemic infection. There are special indications in patients with peripheral arterial occlusive disease,diabetes or immunosuppression. Topical use of antibiotics should be abandoned and replaced by antiseptics. The ,-lactam antibiotics are the antibiotics of first choice for many skin infections. They are usually effective, have a well-defined profile of adverse events and most are affordable. Penicillin G or V are the first line treatment for erysipelas. Infections with Staphylococcus aureus are usually treated with isoxazolyl penicillins or second generation cephalosporins. In mixed infections in patients with diabetes or peripheral arterial occlusive disease,the treatment of choice is metronidazole plus ,-lactam-/,-lactamase inhibitor antibiotics, but quinolones or second generation cephalosporins can also be used, once again with metronidazole. The aim of this review is to define the indications for antibiotics in dermatology, to highlight their modes of action and adverse effects and to make suggestions for rational antibiotic therapy in cutaneous infections frequently encountered in the practice of dermatology. Zusammenfassung Der bisweilen unkritische Einsatz von Antibiotika hat die Resistenzentwicklung beschleunigt und die Sensibilisierungsrate bei Patienten erhöht. Systemische Antibiotika sind bei kutanen Superinfektionen in der Regel dann indiziert, wenn eine schwere lokale Infektion mit Ausbreitung in das umgebende Gewebe vorliegt oder wenn sich gleichzeitig Zeichen einer systemischen Infektion einstellen. Bei peripherer arterieller Verschlusskrankheit, Diabetes mellitus oder Immunsuppression kann die Indikation auch früher gestellt werden. Lokale Antibiotika sollten in der Regel gemieden und durch moderne Antiseptika ersetzt werden. ,-Laktam-Antibiotika stellen für viele bakterielle Infektionserkrankungen in der ambulanten und klinischen Dermatologie die Antibiotika der ersten Wahl dar. Sie sind häufig ausreichend wirksam, besitzen ein gut definiertes Nebenwir-kungsprofil und sind zumeist preisgünstig. So wird das klassische Streptokokken-Erysipel mit Penicillin G oder V therapiert, bei Infektionen durch S. aureus kommen primär Isoxazolyl-Penicilline oder Zweit-Generations-Cephalosporine zum Einsatz. Im Falle von Mischinfektionen bei Diabetes mellitus oder pAVK sind ,-Laktam/,-Laktamaseinhibitoren indiziert, alternativ auch Chinolone oder Zweitgenerations-Cephalosporine, jeweils in Kombination mit Metronidazol. Diese Übersicht möchte die Indikationen für Antibiotika in der Dermatologie aufzeigen, das Wichtigste zu deren Wirkungsweise und Nebenwirkungen aufzählen und Therapievorschläge für häufige Infektionen der Haut in der dermatologischen Praxis geben. [source]

Analysis of mixed infections by multiple genotypes of human cytomegalovirus in immunocompromised patients

Genotypic analysis of two hypervariable human cytomegalovirus genes

JOURNAL OF MEDICAL VIROLOGY, Issue 9 2008
Amanda J. Bradley
Abstract Most human cytomegalovirus (HCMV) genes are highly conserved in sequence among strains, but some exhibit a substantial degree of variation. Two of these genes are UL146, which encodes a CXC chemokine, and UL139, which is predicted to encode a membrane glycoprotein. The sequences of these genes were determined from a collection of 184 HCMV samples obtained from Africa, Australia, Asia, Europe, and North America. UL146 is hypervariable throughout, whereas variation in UL139 is concentrated in a sequence encoding a potentially highly glycosylated region. The UL146 sequences fell into 14 genotypes, as did all previously reported sequences. The UL139 sequences grouped into 8 genotypes, and all previously reported sequences fell into a subset of these. There were minor differences among continents in genotypic frequencies for UL146 and UL139, but no clear geographical separation, and identical nucleotide sequences were represented among communities distant from each other. The frequent detection of multiple genotypes indicated that mixed infections are common. For both genes, the degree of divergence was sufficient to preclude reliable sequence alignments between genotypes in the most variable regions, and the mode of evolution involved in generating the genotypes could not be discerned. Within genotypes, constraint appears to have been the predominant mode, and positive selection was detected marginally at best. No evidence was found for linkage disequilibrium. The emerging scenario is that the HCMV genotypes developed in early human populations (or even earlier), becoming established via founder or bottleneck effects, and have spread, recombined and mixed worldwide in more recent times. J. Med. Virol. 80:1615,1623, 2008. © 2008 Wiley-Liss, Inc. [source]

A temperature-regulated Campylobacter jejuni gluconate dehydrogenase is involved in respiration-dependent energy conservation and chicken colonization

MOLECULAR MICROBIOLOGY, Issue 2 2008
Mohanasundari Pajaniappan
Summary Campylobacter jejuni is a gastrointestinal pathogen of humans but can asymptomatically colonize the avian gut. C. jejuni therefore grows at both 37°C and 42°C, the internal temperatures of humans and birds respectively. Microarray and proteomic studies on temperature regulation in C. jejuni strain 81,176 revealed the upregulation at 42°C of two proteins, Cj0414 and Cj0415, orthologous to gluconate dehydrogenase (GADH) from Pectobacterium cypripedii. 81,176 demonstrated GADH activity, converting d -gluconate to 2-keto- d -gluconate, that was higher at 42°C than at 37°C. In contrast, cj0414 and cj0415 mutants lacked GADH activity. Wild-type but not cj0415 mutant bacteria exhibited gluconate-dependent respiration. Neither strain grew in defined media with d -gluconate or 2-keto- d -gluconate as a sole carbon source, revealing that gluconate was used as an electron donor rather than as a carbon source. When administered to chicks individually or in competition with wild-type, the cj0415 mutant was impaired in establishing colonization. In contrast, there were few significant differences in colonization of BALB/c-ByJ mice in single or mixed infections. These results suggest that the ability of C. jejuni to use gluconate as an electron donor via GADH activity is an important metabolic characteristic that is required for full colonization of avian but not mammalian hosts. [source]

Molecular analysis of the root canal microbiota associated with endodontic treatment failures

MOLECULAR ORAL MICROBIOLOGY, Issue 4 2008
M. Sakamoto
Introduction:, The failure of endodontic treatment is usually caused by persistent/secondary intraradicular infections and Enterococcus faecalis has been considered to be the main pathogen involved. Nevertheless, the breadth of bacterial diversity involved with endodontic treatment failures remains to be consistently explored by culture-independent approaches. Methods:, This study determined the intraradicular microbiota of root-canal-treated teeth with post-treatment apical periodontitis using 16S ribosomal RNA gene clone library analysis. Results:, Bacteria were present in all cases, confirming the infectious etiology of post-treatment disease. Seventy-four bacterial taxa belonging to six phyla were found in the nine cases investigated. Of these, 55% were identified as as-yet-uncultivated phylotypes, which also made up a significant proportion of the microbiota in many cases. Twenty-five new phylotypes were identified. Most teeth harbored a mixed consortium, with a mean number of 10 taxa per case. Only 11 taxa were found in more than one case, revealing a high interindividual variability in the composition of the microbiota. Conclusion:, The current findings revealed new candidate endodontic pathogens, including as-yet-uncultivated bacteria and taxa other than E. faecalis, which may participate in the mixed infections associated with post-treatment apical periodontitis. [source]

Chronic lung disease in human immunodeficiency virus (HIV) infected children,

PEDIATRIC PULMONOLOGY, Issue 1 2008
Heather J. Zar
Abstract The development of chronic lung disease is common in HIV-infected children. The spectrum of chronic HIV-associated lung disease includes lymphocytic interstitial pneumonia (LIP), chronic infections, immune reconstitution inflammatory syndrome (IRIS), bronchiectasis, malignancies, and interstitial pneumonitis. Chronic lung disease may result from recurrent or persistent pneumonia due to bacterial, mycobacterial, viral, fungal or mixed infections. In high tuberculosis (TB) prevalence areas, M. tuberculosis is an important cause of chronic respiratory illness. With increasing availability of highly active antiretroviral therapy (HAART) for children in developing countries, a rise in the incidence of IRIS due to mycobacterial or other infections is being reported. Diagnosis of chronic lung disease is based on chronic symptoms and persistent chest X-ray changes but definitive diagnosis can be difficult as clinical and radiological findings may be non-specific. Distinguishing LIP from miliary TB remains a difficult challenge in HIV-infected children living in high TB prevalence areas. Treatment includes therapy for specific infections, pulmonary clearance techniques, corticosteroids for children with LIP who are hypoxic or who have airway compression from tuberculous nodes and HAART. Children who are taking TB therapy and HAART need adjustments in their drug regimes to minimize drug interactions and ensure efficacy. Preventative strategies include immunization, chemoprophylaxis, and micronutrient supplementation. Early use of HAART may prevent the development of chronic lung disease. Pediatr Pulmonol. 2008; 43:1,10. © 2007 Wiley-Liss, Inc. [source]

Comparative whitefly transmission of Tomato chlorosis virus and Tomato infectious chlorosis virus from single or mixed infections

PLANT PATHOLOGY, Issue 2 2009
A. Dalmon
Tomato chlorosis virus (ToCV) and Tomato infectious chlorosis virus (TICV) are two criniviruses that are emerging worldwide, and induce similar yellowing diseases in tomato crops. While TICV is transmitted only by Trialeurodes vaporariorum, ToCV is transmitted by three whitefly species in two genera Trialeurodes vaporariorum, T. abutilonea and Bemisia tabaci. The efficiency of transmission by T. vaporariorum from plants infected by one virus or by both was compared, and the probability of virus transmission by a single whitefly was derived from group testing experiments. The estimated transmission probabilities ranged from 0·01 to 0·13, and were not significantly different between ToCV and TICV, or between single and mixed infections. Experiments using B. tabaci as a vector and source plants infected by TICV and ToCV did not reveal any functional trans-complementation for transmission of TICV by ToCV, suggesting that if this phenomenon occurs in nature, it is at a very low frequency. Possible reasons why TICV did not establish in southern France while ToCV is now endemic are discussed. [source]

Two New Species of Symbiotic Ciliates from the Respiratory Tract of Cetaceans with Establishment of the New Genus Planilamina n. gen. (Dysteriida, Kyaroikeidae)

THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 6 2006
HONGWEI MA
ABSTRACT. Examination of mucus discharged from the blowhole of Atlantic bottlenose dolphin (Tursiops truncatus) at Marine Life Oceanarium, Gulfport, Mississippi, and false killer whale (Pseudorca crassidens) and Atlantic bottlenose dolphin at SeaWorld Orlando, Orlando, Florida, using live observations and protargol impregnation revealed mixed infections of Kyaroikeus cetarius and two new species. Planilamina n. gen. is characterized by a C-shaped argentophilic band located along the laterally flattened margin of cell and extending from the cell apex to subposterior cone-shaped podite; a deep oral cavity containing one short preoral kinety, two circumoral kineties, seven to 13 infundibular kineties, and a cytostome; a broadly funnel-shaped cytopharynx reinforced by argentophilic fibers but without nematodesmata; closely packed postoral kinetofragments set in a pocket located anterior left of the podite; and somatic kineties as a right field closely situated at the right surface and a left field bordering the anterior left margin of the oral cavity. The type species for the genus, Planilamina ovata n. sp., is distinguished from its sister species Planilamina magna n. sp. by the following characteristics: body size (28,65 × 20,43 ,m vs. 57,90 × 40,63 ,m), number of right field kineties (38,55 vs. 79,99), and position of the anterior end of the leftmost kinety in the right somatic field (anterior one-third vs. mid-body). The morphogenesis of Planilamina ovata is similar to that of K. cetarius. The diagnosis of Kyaroikeidae is emended to accommodate the new genus. [source]

Epidemics of Tomato torrado virus, Pepino mosaic virus and Tomato chlorosis virus in tomato crops: do mixed infections contribute to torrado disease epidemiology?

ANNALS OF APPLIED BIOLOGY, Issue 3 2010
P. Gómez
Torrado disease was first observed in protected tomato crops in the Murcia province of Spain in spring 2001, causing serious concern to regional tomato producers. The disease-causing agent was initially identified as a picorna-like bipartite plant RNA virus, now known as Tomato torrado virus (ToTV), but several additional torradoviruses inducing similar disease symptoms have been described more recently. We studied the incidence of torradoviruses between 2005 and 2008 in two parts of Murcia (Spain) where tomato crops are grown commercially. We also analysed the potential association among ToTV, Pepino mosaic virus (PepMV) and Tomato chlorosis virus (ToCV) in samples showing torrado symptoms of varying severity. ToTV was the only torradovirus found in the samples (predominantly as single infections), but double and triple infections comprising ToTV, PepMV and/or ToCV were also detected. There was no evidence of a specific association among the viruses as the frequencies of mixed infections did not deviate from those expected to occur by chance. Statistical analysis of the potential association between torrado symptoms and the type of infection (single or multiple) was inconclusive. To determine whether co-infections with ToTV and PepMV have any marked influence on the torrado disease, we analysed torrado symptom severity and virus accumulation in tomato plants experimentally infected with ToTV-CE, PepMV-Sp13 and PepMV-PS5 in single and mixed infections. The severity of the torrado symptoms was not affected by the presence of PepMV. In single infections, the ToTV titre remained very low, reaching its maximum in the early stages of infection and declining rapidly thereafter, whereas the disease symptoms became more severe over the same timescale. In mixed infections, the accumulation of both ToTV and PepMV was altered with respect to single infections, and the magnitude of this alteration appeared to be virus and strain specific. Therefore, ToTV and PepMV mixed infections may modulate the epidemiology of both viruses in a complex way by altering virus fitness. The impact of our studies on efforts to track and prevent the spread of torrado disease is discussed. [source]

Survey of the incidence and distribution of viruses infecting yam (Dioscorea spp.) in Ghana and Togo

ANNALS OF APPLIED BIOLOGY, Issue 2 2010
A.O. Eni
Yam leaves were collected during surveys of major yam producing agro-ecological zones (AEZs) in Ghana (n = 628) and Togo (n = 218) respectively, in 2005. Leaf tissues were tested for Cucumber mosaic virus (CMV), Dioscorea mottle virus (DMoV), Yam mild mosaic virus (YMMV), Yam mosaic virus (YMV) and badnaviruses by enzyme-linked immunosorbent assay (ELISA), immunocapture-polymerase chain reaction (IC-PCR) and/or IC-reverse transcription-PCR (IC-RT-PCR). Eighty-one percent (370/459) and 78.9% (127/161) of symptomatic leaf samples from Ghana and Togo, respectively and 56.2% (95/169) and 57.9% (33/57) of non-symptomatic leaf samples, reacted positive to CMV, YMMV, YMV and/or badnaviruses, but DMoV was not detected. The highest incidence of YMV and badnaviruses was observed in the forest,savannah transition and Guinea savannah AEZ respectively in Ghana. In Togo, incidence of badnaviruses across the four AEZ ranged from 50 to 57.9%; however, Savane Derivée Seche AEZ had the highest incidence of badnaviruses (57.9%), YMV (34.2%) and CMV (7.9%). Mixed infection of badnaviruses and YMMV was the most frequent (105 of 276 mixed infections) in the two countries and Dioscorea alata was more heavily infected than D. rotundata in both countries. [source]

High frequency of multiple HPV types in cervical specimens from Danish women

APMIS, Issue 2 2009
NINA MEJLHEDE
Genital human papillomavirus infection (HPV) is common and usually harmless. However, chronic cervical infection with high-risk HPV types can cause cell changes that may eventually lead to cancer. To determine the frequency of individual HPV types among mixed infections, we examined the type distribution among cervical specimens from more than 1000 Danish women. We also examined the HPV type distribution and the frequency of single and multiple HPV types for specimens from 113 women who underwent conization and were diagnosed with cervical intraepithelial neoplasia grade II or worse (CIN2+). Using microarray technology, we found that 49% of the HPV-positive patients were infected with multiple HPV types. Among the CIN2+ diagnosed women, this frequency was 41%. The most frequently found high-risk HPV type was HPV-16, which was found in 25% of the HPV-positive cervical specimens. Among the HPV positive CIN2+ diagnosed women, 48% were HPV-16 positive. Women younger than 30 years of age had a higher frequency of multiple infections (61%) than women older than 30 years (39%). We conclude that cervical infection with multiple HPV types is common among women in all age groups and among women with or without the diagnosis of CIN2+. [source]