scholarly journals (257) Pepino Mosaic Virus: Variability in U.S. Isolates

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1089B-1089
Author(s):  
Clarissa J. Maroon-Lango ◽  
Mary Ann Guaragna ◽  
Ramon Jordan ◽  
John Hammond ◽  
Murali Bandla ◽  
...  

Pepino mosaic virus (PepMV) was first found in pepino (Solanum muricatum) growing in coastal Peru in 1974 and described in 1980; it reappeared in protected tomato (Lycopersiconesculentum) in the Netherlands in 1999. Since then, it has been reported to occur in tomato in several countries including Austria, Belgium, Canada, France, Germany, Italy, Peru, Spain and the Canary Islands, the United Kingdom, and in 11 states within the United States. Three strains of PepMV found in the United States have been cloned and sequenced. Full-length genomic sequences were obtained for two strains, PepMV-US1 and PepMV-US2, from co-infected tomato plant samples from Arizona. The 3'-end sequence of PepMV-US3 came from infected tomato fruits from Maryland. The genome organization, motifs and domains typical of the genus Potexvirus, and of other PepMV isolates, were found in full-length sequences of both US1 and US2 isolates. Direct comparison of US1 and US2 at the nucleotide level revealed an 86.3% identity; whereas, when individually compared to the French and Spanish isolates, which share ∼99% identity at the nucleotide level, US1 and US2 had 82% and 79% identities to each, respectively. Pair-wise gene-for-gene comparisons between United States and European isolates revealed a similar trend. While unique, US1 is more closely related to the previously reported European isolates than is US2. The CP of US3 is nearly identical to the European isolates at the amino acid level. None of 18 tomato germplasm accessions or 10 cultivars were resistant to mechanical inoculation with US3; in contrast, no infection was detected in nine pepper cultivars or four germplasm accessions. Plants grown from seeds of infected tomato fruits did not test positive for PepMV.

Plant Disease ◽  
2001 ◽  
Vol 85 (10) ◽  
pp. 1121-1121 ◽  
Author(s):  
C. J. French ◽  
M. Bouthillier ◽  
M. Bernardy ◽  
G. Ferguson ◽  
M. Sabourin ◽  
...  

During the winter of 2000, tomatoes (Lycopersicon esculentum) with a bright yellow leaf mosaic were observed in a commercial greenhouse in southern Ontario, Canada. Examination of leaf extracts, using leaf dips and immunosorbent absorption electron microscopy (ISEM), showed flexuous rods consistent with the potexvirus group. Polyclonal antibodies raised against the original Peruvian Pepino mosaic virus (PepMV) isolate (1) and commercial antibodies obtained from Deutsche Sammlung von Mikro-organismen und Zellkulturen (DSMZ), GmbH, Braunsweig, Germany, and Plant Research International (PRI), Wageningen, the Netherlands, were used in ISEM. Leaves tested positive in double-antibody sandwich-enzyme-linked immunosorbent assay (ELISA) with antibodies from DSMZ and PRI. A triple-antibody sandwich-ELISA obtained from Adgen Ltd. (Nellies Gate, UK) gave similar results. Potato virus X did not react with PepMV antiserum in ELISA. Positive PepMV ELISA controls were a U.K. and a Dutch isolate supplied by R. Mumford and R. A. A. van Vlugt, respectively, and DSMZ. Using primers generated from a sequence of the RNA polymerase region of a U.K. PepMV isolate (R. Mumford, unpublished data), a reverse transcription-polymerase chain reaction test showed the expected 312-bp amplicon for the Canadian, Dutch, and U.K. isolates. The primer sequences used were forward 5′ CTA TTA CAA CTC CGG AAG CCA 3′ and reverse 5′ TGG TCT GGC CAG GCT TTG AC 3′. The three isolates were maintained in tomato cv. Bush Beefsteak. When mechanically inoculated on L. esculentum cv. Rapsodie, the Canadian isolate caused a bright yellow mosaic in 1 to 2 weeks, while the two European isolates caused a faint yellow mosaic and mild puckering of the leaves. When mechanically inoculated on 17 indicator plants, the Canadian isolate had a host range similar to the U.K. isolate. The most striking difference in symptoms occurred in L. pimpinellifolium, in which the Canadian isolate caused a yellow mosaic, the Dutch isolate caused no symptoms, and the U.K. isolate caused a marked puckering of the leaves, suggesting virus strain differences among the isolates. Tomato fruits originating from the United States were collected during border inspections by the Canadian Food Inspection Agency and tested for PepMV by ELISA with antisera from DSMZ. PepMV was not detected in 7 samples from California, but was detected in 6 of 12 samples from Colorado, 6 of 7 samples from Arizona, and 1 of 5 samples from Texas. PepMV was originally isolated from pepino (Solanum muricatum) in Peru in 1980 (1) and subsequently from tomato in the Netherlands in 1999 (2). To our knowledge, this is the first report of PepMV in North America. References: (1) R. Jones et al. Ann. Appl. Biol. 94:61, 1980. (2) R. A. A. van Vlugt et al. Plant Dis. 84:103, 2000.


Plant Disease ◽  
2013 ◽  
Vol 97 (9) ◽  
pp. 1259-1259 ◽  
Author(s):  
O. A. Abdalla ◽  
A. Ali

During the 2010 to 2011 growing seasons, nine cucurbit leaf samples including cantaloupe, cucumber, pumpkin, squash, and watermelon, showing mosaic and mottling, were collected from fields in the Homestead and Tampa areas in Florida (1). Eight of the nine samples were positive by dot-immunobinding assay (DIBA) and reverse transcription (RT)-PCR for either Watermelon mosaic virus (WMV), Papaya ringspot virus (PRSV-W), or mixed infection of both viruses. One squash sample from the Homestead area showing unique symptoms including chlorotic spots, yellowing, mottling, vein clearing, and mild mosaic was negative by RT-PCR against PRSV-W, Squash vein yellowing virus (SqVYV), WMV, and Zucchini yellow mosaic virus (ZYMV).The presence of virus-like particles (VLP) from symptomatic squash leaves (1) was prepared as described previously (2). Typical potyvirus-like particles ~700 nm long and 12 to 14 nm wide were observed by electron microscope from VLP preparations. Analysis of VLP on SDS-PAGE demonstrated a slightly larger coat protein (CP) (37 kDa compared with PRSV-W [35 kDa]). Sap from symptomatic squash leaf samples or VLP was mechanically inoculated to 10 squash seedlings at cotyledon stage using 0.1 M K2HPO4 buffer. Chlorotic spots were observed on the first true leaf 7 days post inoculation. However, symptoms became more severe by 2 to 3 weeks post inoculation and systemically infected leaves showed chlorosis and mottling similar to the original symptoms when tissues were collected from the field. Mock-inoculated control squash seedlings did not produce any symptoms. Symptomatic leaves from mechanically infected squash plants were used for VLP preparations and virus particles and size of the CP on SDS-PAGE was observed as before. Total RNA was extracted from VLP (2) and tested by RT-PCR using universal Potyviridae primers (forward primer 5′-CACGGATCCCGGG (T)17AGC and reverse primer 5′-GGBAAYAAYAGYGGDCARCC (3) to amplify a fragment from the 3′ end of the genome (including part of NIb gene, whole CP). A band of 1.2 kb was observed when the PCR product was analyzed on 1% agarose gel. PCR product was purified using QIAquick PCR Purification Kit (QIAGEN, USA), cloned (pGEM-T Easy Vector, Promega, USA), and sequenced in both directions. Consensus sequence was obtained from at least five clones and submitted to GenBank (KC522968). A BLASTn comparing the sequence from the squash potyvirus to others in GenBank found the highest similarity was 72.0% at nucleotide level and 64.8% at amino acid level with PRSV-W (JN831646), and less than 70% nucleotide similarity with WMV (NC_006262) and SqVYV (NC_010521). Based on the particle morphology, CP size on SDS-PAGE, nucleotide identity with other cucurbit potyviruses, and unique symptoms, it is concluded that this could be a new potyvirus. The threshold for classifying distinct species in Potyviridae is less than 76% identity at nucleotide level for either CP gene or the whole genome (4). This virus has been tentatively named as Squash chlorosis mottling virus (SqCMV). Florida is one of the leading states in acreage and production of cucurbits in the United States. The emergence of this new virus could be a potential future threat to cucurbits production. References: (1) A. Ali et al. Plant Health Progress. Online publication. doi:10.1094/PHP-2012-0824-01-RS, 2012. (2) A. Ali et al. Plant Dis. 96:243, 2012. (3) A. Gibbs and A. Mackenzie. J. Virol. Methods 63:9, 1997. (4) A. M. Q. King et al. Virus Taxonomy-ICTV 9th Report:1071, 2012.


Plant Disease ◽  
2008 ◽  
Vol 92 (12) ◽  
pp. 1683-1688 ◽  
Author(s):  
Kai-Shu Ling ◽  
William M. Wintermantel ◽  
Michael Bledsoe

In just a few short years, pepino mosaic disease has quickly become endemic in greenhouse tomatoes around the world. Although three genotypes of Pepino mosaic virus (PepMV) were identified in the United States, genetic composition of PepMV in greenhouse tomato crops in North America has not been determined. In this study, genetic variability and population structure of PepMV were evaluated through nucleotide sequence comparison and phylogenetic analysis of two genomic regions (helicase domain and TGB2-3) derived from 91 cDNA clones that were derived from 31 field-collected samples. These samples were collected from several major greenhouse tomato facilities in five states in the United States and two provinces in Canada. All four major genotypes of PepMV (EU, US1, US2, and CH2) were found in North America. Three distinct genotypes (EU, US1, and US2) were found in mixed infection in samples collected from Arizona and Colorado, two genotypes (EU and CH2) in Texas, and a single genotype (EU) in Alabama and California and the provinces of British Columbia and Ontario in Canada. The complexity of population genetics of PepMV in the United States poses an additional challenge to the greenhouse tomato industry because a tomato cultivar with durable resistance to multiple genotypes of PepMV may be harder to develop.


2008 ◽  
Vol 9 (1) ◽  
pp. 42 ◽  
Author(s):  
Rayapati A. Naidu ◽  
Gandhi Karthikeyan

The ornamental Chinese wisteria (Wisteria sinensis) is a woody perennial grown for its flowering habit in home gardens and landscape settings. In this brief, the occurrence of Wisteria vein mosaic virus (WVMV) was reported for the first time in Chinese wisteria in the United States of America. Accepted for publication 18 June 2008. Published 18 August 2008.


Plant Disease ◽  
2013 ◽  
Vol 97 (1) ◽  
pp. 44-52 ◽  
Author(s):  
Vessela Mavrodieva ◽  
Delano James ◽  
Karen Williams ◽  
Sarika Negi ◽  
Aniko Varga ◽  
...  

Four of 19 Prunus germplasm accessions hand carried from the Ukraine into the United States without authorization were found to be infected with Plum pox virus (PPV). Of the three isolates characterized, isolates UKR 44189 and UKR 44191 were confirmed to be isolates of PPV strain W, and UKR 44188 was confirmed to be an isolate of PPV strain D. UKR 44189 and UKR 44191 are very closely related to the PPV strain W isolate LV-145bt (HQ670748) from Latvia. Nucleotide and amino acid sequence identities between these three isolates were greater than 99%. This indicates that the isolates are very closely related and likely originated from a common source. The high genetic diversity among PPV-W strain isolates allowed the identification of potential recombination events between PPV isolates. It appears also that GF 305 peach and Prunus tomentosa are not hosts for the PPV isolate UKR 44189.


Plant Disease ◽  
2014 ◽  
Vol 98 (5) ◽  
pp. 701-701
Author(s):  
K.-S. Ling ◽  
R. Li ◽  
D. Groth-Helms ◽  
F. M. Assis-Filho

In recent years, viroid disease outbreaks have resulted in serious economic losses to a number of tomato growers in North America (1,2,3). At least three pospiviroids have been identified as the causal agents of tomato disease, including Potato spindle tuber viroid (PSTVd), Tomato chlorotic dwarf viroid (TCDVd), and Mexican papita viroid (MPVd). In the spring of 2013, a severe disease outbreak with virus-like symptoms (chlorosis and plant stunting) was observed in a tomato field located in the Dominican Republic, whose tomato production is generally exported to the United States in the winter months. The transplants were produced in house. The disease has reached an epidemic level with many diseased plants pulled and disposed of accordingly. Three samples collected in May of 2013 were screened by ELISA against 16 common tomato viruses (Alfalfa mosaic virus, Cucumber mosaic virus, Impatiens necrotic spot virus, Pepino mosaic virus, Potato virus X, Potato virus Y, Tobacco etch virus, Tobacco mosaic virus, Tobacco ringspot virus, Tomato aspermy virus, Tomato bushy stunt virus, Tomato mosaic virus, Tomato ringspot virus, Tomato spotted wilt virus, Groundnut ringspot virus, and Tomato chlorotic spot virus), a virus group (Potyvirus group), three bacteria (Clavibacter michiganensis subsp. michiganensis, Pectobacterium atrosepticum, and Xanthomonas spp.), and Phytophthora spp. No positive result was observed, despite the presence of symptoms typical of a viral-like disease. Further analysis by RT-PCR using Agdia's proprietary pospiviroid group-specific primer resulted in positive reactions in all three samples. To determine which species of pospiviroid was present in these tomato samples, full-genomic products of the expected size (~360 bp) were amplified by RT-PCR using specific primers for PSTVd (4) and cloned using TOPO-TA cloning kit (Invitrogen, CA). A total of 8 to 10 clones from each isolate were selected for sequencing. Sequences from each clone were nearly identical and the predominant sequence DR13-01 was deposited in GenBank (Accession No. KF683200). BLASTn searches into the NCBI database demonstrated that isolate DR13-01 shared 97% sequence identity to PSTVd isolates identified in wild Solanum (U51895), cape gooseberry (EU862231), or pepper (AY532803), and 96% identity to the tomato-infecting PSTVd isolate from the United States (JX280944). The relatively lower genome sequence identity (96%) to the tomato-infecting PSTVd isolate in the United States (JX280944) suggests that PSTVd from the Dominican Republic was likely introduced from a different source, although the exact source that resulted in the current disease outbreak remains unknown. It may be the result of an inadvertent introduction of contaminated tomato seed lots or simply from local wild plants. Further investigation is necessary to determine the likely source and route of introduction of PSTVd identified in the current epidemic. Thus, proper control measures could be recommended for disease management. The detection of this viroid disease outbreak in the Dominican Republic represents further geographic expansion of the viroid disease in tomatoes beyond North America. References: (1). K.-S. Ling and M. Bledsoe. Plant Dis. 93:839, 2009. (2) K.-S. Ling and W. Zhang. Plant Dis. 93:1216, 2009. (3) K.-S. Ling et al. Plant Dis. 93:1075, 2009. (4) A. M. Shamloul et al. Can. J. Plant Pathol. 19:89, 1997.


Plant Disease ◽  
2010 ◽  
Vol 94 (7) ◽  
pp. 924-924 ◽  
Author(s):  
C. Hernandez-Zepeda ◽  
T. Isakeit ◽  
A. Scott ◽  
J. K. Brown

During the okra growing season from August to November of 2009, symptoms reminiscent of geminivirus infection were observed on 75% of ‘Green Emerald’ Abelmoschus esculentus (L.) Moench, plants in a 0.2-km2 field in Hidalgo County, TX. Visible symptoms consisted of irregular yellow patches on leaves, distinctive yellow borders on leaf edges, and chlorosis of subsequently developing leaves. The whitefly vector of begomoviruses, Bemisia tabaci (Genn.), infested okra plants in the early growth stages during late July 2009. Total DNA was isolated from the leaves of three symptomatic okra plant samples (1) and used as the PCR template to amplify a 575-bp fragment of the coat protein gene (CP) using the universal begomovirus primers AV494 and AC1048 (2). PCR products of the expected size were cloned into the pGEM-T Easy (Promega, Madison, WI) and sequenced using the universal M13F and M13 R primers. ClustalV alignment indicated 99 to 100% shared nucleotide (nt) identity, and BLAST analysis revealed that the closest relative was Okra yellow mosaic Mexico virus - Tetekalitla (OkYMMV) (GenBank Accession No. EF591631) at 98%. To amplify the full-length DNA-A and a possible cognate DNA-B component, one plant that was positive by CP-PCR and DNA sequencing was selected for further analysis. Total DNA from this plant was used as template for a second detection method that consisted of rolling circle amplification (RCA) using the TempliPhi 100 Amplification System (GE Healthcare). RCA is a non-sequence-specific approach that permits amplification of circular DNA. The RCA products were linearized to release unit length ~2.6 kb DNA-A and DNA-B components using BamHI, and EcoRI, respectively. These products were cloned into pGEM3zf+ (Promega) and sequenced using M13F and M13 R primers and then by primer walking (>300 base overlap). Full-length DNA-A and DNA-B components were obtained, respectively, at 2,613 bp (GenBank Accession No. HM035059) and 2,594 bp (GenBank Accession No HM035060). Alignment of the DNA-A component using ClustalV (MegAlign, DNASTAR, Madison, WI) with begomoviral sequences available in GenBank indicated that it was 99% identical to OkYMMV DNA-A (GenBank Accession No. DQ022611). The closest relative to the DNA-B component (ClustalV) was Sida golden mosaic virus (SiGMV) (GenBank Accession No. AJ250731) at 73%. The nt identity of the 172-nt ‘common region’ present in the DNA-A and DNA-B components was 99%, and the iterons (predicted Rep binding motif) were identical for the two components, indicating that they are a cognate pair. The genome organization was typical of other New World bipartite begomoviruses. The economic losses due to infection by this virus could not be determined because an early freeze killed the plants. Hidalgo County is adjacent to Tamaulipas, Mexico, where ~50 km2 of okra are grown and the whitefly vector is also present. The identification of OkYMMV based on two independent detection methods, and the presence of begomovirus-like symptoms together with the whitefly vector, provide robust evidence for the association of OkYMMV-TX with diseased okra plants. To our knowledge, this is the first report of OkYMMV-TX infecting okra crops in Texas and in the continental United States. References: (1) J. J. Doyle and J. L. Doyle. Focus 12:13, 1990. (2) S. Wyatt and J. K. Brown. Phytopathology 86:1288, 1996.


2020 ◽  
Vol 18 (4) ◽  
pp. e10SC05
Author(s):  
Ivana Stankovic ◽  
Ana Vucurovic ◽  
Katarina Zecevic ◽  
Branka Petrovic ◽  
Danijela Ristic ◽  
...  

Aim of study: To report the occurrence of Pepino mosaic virus (PepMV) on tomato in Serbia and to genetically characterize Serbian PepMV isolates.Area of study: Tomato samples showing virus-like symptoms were collected in the Bogojevce locality (Jablanica District, Serbia).Material and methods: Collected tomato samples were assayed by DAS-ELISA using antisera against eight economically important or quarantine tomato viruses. Three selected isolates of naturally infected tomato plants were mechanically transmitted to tomato ‘Novosadski jabučar’ seedlings. For confirmation of PepMV infection, RT-PCR was performed using specific primers PepMV TGB F/PepMV UTR R. Maximum-likelihood phylogenetic tree was constructed with 47 complete CP gene sequences of PepMV to determine the genetic relationship of Serbian PepMV isolates with those from other parts of the world.Main results: The results of DAS-ELISA indicated the presence of PepMV in all tested samples. Mechanically inoculated ‘Novosadski jabučar’ seedlings expressed yellow spots and light and dark green patches, bubbling, and curled leaves. All tested tomato plants were RT-PCR positive for the presence of PepMV. The CP sequence analysis revealed that the Serbian PepMV isolates were completely identical among themselves and shared the highest nucleotide identity of 95.1% (99.2% aa identity) with isolate from Spain (FJ263341). Phylogenetic analysis showed clustering of the Serbian PepMV isolates into CH2 strain, but they formed separate subgroup within CH2 strain.Research highlights: This is the first data of the presence of PepMV in protected tomato production in Serbia. Considering increased incidence and rapid spread in Europe, the presence of PepMV on tomato could therefore represent serious threat to this valuable crop in Serbia.


Plant Disease ◽  
1997 ◽  
Vol 81 (10) ◽  
pp. 1214-1214 ◽  
Author(s):  
J. R. Fisher ◽  
S. T. Nameth

Creeping bugleweed (Ajuga reptans L.) is a perennial ornamental commonly grown as a ground cover in temperate climates. Commercial samples of the A. reptans cultivars Royalty, var. Atropurpurea Bronze, Bronze Beauty, and Burgundy Glow showing mosaic and ringspot symptoms were tested for the presence of virus infection by direct antibody sandwich enzyme-linked immunosorbent assay (ELISA) and viral-associated double-stranded (ds) RNA analysis. Cucumber mosaic cucumovirus (CMV) was detected by ELISA and dsRNA analysis in symptomatic samples of all cultivars tested. ELISA values were considered positive if the absorbance values were twice the negative control. Negative control values were established with asymptomatic tissue of the cv. Bronze Beauty. Tobacco streak ilarvirus (TSV) was detected only by ELISA in symptomatic samples of all cultivars except Royalty. No dsRNA suggestive of TSV was detected. Alfalfa mosaic virus (AMV) was detected by ELISA and dsRNA analysis in symptomatic samples of all cultivars tested except Royalty and var. Atropurpurea Bronze. dsRNA analysis also indicated the presence of a low molecular weight, possible satellite (sat) RNA associated with all symptomatic and asymptomatic Royalty and var. Atropurpurea Bronze plants tested. Northern (RNA) blot analysis with a digoxigenin-labeled full-length clone of the (S) CARNA-5 (-) CMV satRNA (ATCC no. 45124) confirmed that the low molecular weight RNA associated with the Royalty and var. Atropurpurea Bronze cultivars was indeed CMV satRNA. Only AMV has been previously reported in A. reptans in the United States (1). This is the first report of CMV and its satRNA, as well as TSV, in A. reptans in the United States. Reference: (1) W. T. Schroeder and R. Provvidenti. Plant Dis. Rep. 56:285, 1972.


Plant Disease ◽  
2006 ◽  
Vol 90 (6) ◽  
pp. 833-833 ◽  
Author(s):  
C. A. Baker ◽  
L. Breman ◽  
L. Jones

In the fall of 1998, the Division of Plant Industry (DPI) received vegetative propagations of Scutellaria longifolia (skullcap) with symptoms of foliar mosaic, chlorotic/necrotic ringspots, and wavy line patterns from a nursery in Manatee County. Flexuous particles approximately 500 nm long were found with electron microscopy. The plants tested positive for Papaya mosaic virus (PaMV) in an enzyme-linked immunosorbent assay (ELISA) test with antiserum to PaMV (Agdia, Elkhart, IN). However, in immunodiffusion tests (antiserum from D. Purcifull, University of Florida), this virus gave a reaction of partial identity indicating it was related but not identical to PaMV (1). The original infected plants were kept in a greenhouse. In January 2005, a specimen of Crossandra infundibuliformis (firecracker plant) with mosaic symptoms was submitted to the DPI from a nursery in Alachua County. Inclusions found with light microscopy and particles found with electron microscopy indicated that this plant was infected with a potexvirus. This was confirmed by reverse transcription-polymerase chain reaction (RT-PCR) with primers designed to detect members of the virus family Potexviridae (3). These plants reacted positive to PaMV antiserum in ELISA and gave a reaction of partial identity to PaMV in immunodiffusion. A specimen of Portulaca grandiflora (moss rose) with distorted leaves found at a local retail store was also tested and gave the same results. Leaves from each of the three plant species were rubbed onto a set of indicator plants using Carborundum and potassium phosphate buffer. Total RNA was extracted from symptomatic indicator plants of Nicotiana benthamiana. RT-PCR (3) was performed, and PCR products were sequenced directly. Sequences of approximately 700 bp were obtained for all three plant species and showed 98% identity with each other. BLAST search results showed that these sequences were 93% identical to an Alternanthera mosaic virus (AltMV) sequence at the nucleotide level but only 76% identical to PaMV. The amino acid sequences were 98 and 82% identical to AltMV and PaMV, respectively. The PCR products of the virus from Scutellaria sp. were cloned, resequenced, and the sequence was entered into the GenBank (Accession No. DQ393785). The bioassay results matched those found for AltMV in Australia (2) and the northeastern United States (4), except that the Florida viruses infected Datura stramonium and Digitalis purpurea (foxglove). The virus associated with the symptoms of these three plants appears to be AltMV and not PaMV. AltMV has been found in ornamental plants in Australia, Italy, and the United States (Pennsylvania, Maryland, and now Florida). Since this virus is known to infect several plants asymptomatically and can be easily confused with PaMV serologically, it is likely that the distribution of this virus is much wider than is known at this time. References: (1) L. L. Breman. Plant Pathology Circular No. 396. Fla. Dept. Agric. Consum. Serv. DPI, 1999. (2) A. D. W. Geering and J. E. Thomas. Arch Virol 144:577, 1999. (3) A. Gibbs et al. J Virol Methods 74:67, 1998. (4) J. Hammond et al. Arch Virol. 151:477, 2006.


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