Different transmission efficiencies may drive displacement of tomato begomoviruses in the fields in Taiwan

A progressive displacement of Tomato leaf curl Taiwan virus (ToLCTWV) by Tomato yellow leaf curl Thailand virus (TYLCTHV) from 2005 to 2009 has been recorded in tomato fields in Taiwan. Begomoviruses are exclusively transmitted by Bemisia tabaci complex, so we hypothesised that the displacement of tomato begomoviruses in the fields may be due to the invasion of a new virus/vector and the different transmission efficiencies of the viruses by the vectors. The objective of this research was to compare the transmission efficiency of TYLCTHV and ToLCTWV by the B and Q biotypes of B. tabaci complex. When transmission efficiency, virus retention in vector, and latent period for vector transmission were compared, the B biotype transmitted TYLCTHV and ToLCTWV more efficiently than did the Q biotype, and transmitted TYLCTHV more efficiently than ToLCTWV. The B biotype retained both viruses and remained infective throughout adulthood, but the Q biotype did not keep its infectivity, although it did retain both viruses lifelong. The B biotype transmitted TYLCTHV and ToLCTWV with the shortest latent period. In summary, B. tabaci B biotype and TYLCTHV is the best alliance for disease transmission, so we conclude that this may be one of drivers responsible for the displacement of ToLCTWV by TYLCTHV in tomato fields in Taiwan.     

The autophagy pathway participates in resistance to tomato yellow leaf curl virus infection in whiteflies

Macroautophagy/autophagy plays an important role against pathogen infection in mammals and plants. However, little has been known about the role of autophagy in the interactions of insect vectors with the plant viruses, which they transmit. Begomoviruses are a group of single-stranded DNA viruses and are exclusively transmitted by the whitefly Bemisia tabaci in a circulative manner. In this study, we found that the infection of a begomovirus, tomato yellow leaf curl virus (TYLCV) could activate the autophagy pathway in the Middle East Asia Minor 1 (MEAM1) species of the B. tabaci complex as evidenced by the formation of autophagosomes and ATG8-II. Interestingly, the activation of autophagy led to the subsequent degradation of TYLCV coat protein (CP) and genomic DNA. While feeding the whitefly with 2 autophagy inhibitors (3-methyladenine and bafilomycin A₁) and silencing the expression of Atg3 and Atg9 increased the viral load; autophagy activation via feeding of rapamycin notably decreased the amount of viral CP and DNA in the whitefly. Furthermore, we found that activation of whitefly autophagy could inhibit the efficiency of virus transmission; whereas inhibiting autophagy facilitated virus transmission. Taken together, these results indicate that TYLCV infection can activate the whitefly autophagy pathway, which leads to the subsequent degradation of virus. Furthermore, our report proves that an insect vector uses autophagy as an intrinsic antiviral program to repress the infection of a circulative-transmitted plant virus. Our data also demonstrate that TYLCV may replicate and trigger complex interactions with the insect vector.     

Transmission of tomato leaf curl geminiviruses by Bemisia tabaci: effects of virus isolate and vector biotype

Cultures of Bemisia tabaci from Ivory Coast (IC), Pakistan (PK) and USA (US B-type) were compared for the frequency with which they transmitted three tomato geminivirus isolates: Indian tomato leaf curl virus from Bangalore (ITmLCV), and tomato yellow leaf curl viruses from Nigeria (TYLCV-Nig) and Senegal (TYLCV-Sen). Frequency of transmission from tomato to tomato depended both on the whitefly culture and the virus isolate. US B-type and IC whiteflies transmitted TYLCV-Sen more frequently than ITmLCV whereas PK whiteflies transmitted ITmLCV more frequently than TYLCV-Sen. US B-type whiteflies transmitted both viruses four to nine times more frequently than IC whiteflies. TYLCV-Nig was transmitted rarely by US B-type and not at all by IC whiteflies. Previous work indicates that the geminivirus coat protein controls vector transmissibility. The differential adaptation of TYLCV-Sen to transmission by US B-type whiteflies and of ITmLCV to PK whiteflies was associated with a large difference in epitope profile of the coat proteins of the two viruses. Also, the readily transmissible TYLCV-Sen differed appreciably in epitope profile from the poorly transmissible TYLCV-Nig, which reached a consistently greater concentration in source tissues but lacked epitope 18. However, the lack of epitope 18 in ITmLCV did not prevent its transmission by US B-type whiteflies. Differences in frequency and specificity of geminivirus transmission by whitefly cultures from different countries therefore were associated with differences among epitope profiles of the coat proteins of the viruses, but the structural features of the proteins that control transmission remain to be determined.     

两个入侵烟粉虱隐种MEAM1与MED对番茄黄曲叶病毒水平传播能力的比较

【目的】烟粉虱 Bemisia tabaci 是番茄黄曲叶病毒（Tomato yellow leaf curl virus, TYLCV）在自然界的唯一传播媒介,除了可以直接取食获取TYLCV,烟粉虱还可以通过交配获取此植物病毒。虽然前人研究证明了烟粉虱Middle East-Asia Minor 1 （MEAM1）和Mediterranean （MED）隐种都可以通过交配在两性个体之间水平传播TYLCV,但有关MEAM1与MED隐种水平传播TYLCV的能力是否存在差异,不同研究的结果却并不一致。另外,目前尚无关于烟粉虱的水平传播行为是否有助于TYLCV在田间扩散的相关研究。【方法】从浙江、广东、云南和河南4个省份的田间采集MEAM1和MED隐种烟粉虱种群,在室内应用分子标记对各种群所属隐种鉴定后分别建立7个供试种群,然后观察每个种群内带毒成虫与不带毒成虫通过交配在不同性别个体之间水平传播TYLCV的能力,并选用采自广东的MEAM1隐种烟粉虱模拟群体交配实验探究通过交配获毒的烟粉虱个体是否具有传播TYLCV致健康番茄植株发病的能力。【结果】4个省内的MEAM1和MED隐种烟粉虱都可通过交配对TYLCV进行水平传播,但传播频率一般在10%以下。不同省份的MEAM1隐种种群之间在水平传播TYLCV的能力上无显著差异,不同省份的MED隐种种群之间也不存在显著差异。另外,同一省份的MEAM1隐种与MED隐种之间在水平传播TYLCV的能力上也不存在显著差异,而且在两个隐种中,带毒雄虫将病毒水平传播给不带毒雌虫与带毒雌虫将病毒水平传播给不带毒雄虫的频率没有显著差异。研究还表明,采自广东的MEAM1隐种烟粉虱个体通过交配水平获毒后不能致健康番茄植株发病。【结论】综合以上结果,我们推测TYLCV在中国境内两个入侵烟粉虱隐种MEAM1和MED各自种群内个体之间的水平传播概率较低,对该病毒在田间的扩散可能没有作用或作用不大。     

Begomoviruses Associated with Leaf Curl Disease of Tomato in Java,Indonesia*

We report that several begomoviruses are associated with tomato leaf curl disease in Java, Indonesia. Tomato plants with leaf curl symptoms were collected from Bandung (west Java), Purwokerto (central Java), Magelang (central Java) and Malang (east Java) of Indonesia, the major tomato‐growing areas of the country. Viruses were detected using the polymerase chain reaction (PCR), with universal primers for the genus Begomovirus. PCR‐amplified fragments were cloned and sequenced. Based on sequence comparisons and phylogenetic analyses, the viruses were divided into three groups. With respect to amino acid (aa) identities of the N‐terminal halves of the coat proteins compared in this study, group I was most closely related to Ageratum yellow vein virus (AYVV) (97%), Ageratum yellow vein China virus‐[Hn2] (AYVCNV‐[Hn2]) (96%) and Ageratum yellow vein virus‐[Taiwan] (AYVV‐[Tai]) (95%), and ageratum‐infecting begomovirus from Java (99%). Group II had high sequence identity with a tentative species of tomato leaf curl Java virus (ToLCJAV) (96% aa) for the CP. Group III was most closely related to a proposed species of Pepper yellow leaf curl Indonesia virus (PepYLCIDV) (90% aa identity) by its partial CP sequence.     

Detection of three whitefly-transmitted geminiviruses occurring in Europe by tests with heterologous monoclonal antibodies

Selected monoclonal antibodies (MAbs), prepared to particles of African cassava mosaic or Indian cassava mosaic geminiviruses, detected three geminiviruses that occur in Europe: abutilon mosaic virus in Abutilon pictum ‘Thompsonii’, tobacco leaf curl virus in Lonicera japonica var. aureo-reticulata and tomato yellow leaf curl virus in Lycopersicon esculentum. All three viruses were detected in indirect ELISA by MAbs SCR 17 and SCR 20 but they were differentiated by their reactions with SCR 18 and SCR 23. Tobacco leaf curl virus was detected only when reducing agents were included in the leaf extraction medium. Inclusion of sodium sulphite slightly improved detection of tomato yellow leaf curl virus but reducing agents were not needed for detection of abutilon mosaic virus.     

Chinese tomato yellow leaf curl virus--a new species of geminivirus

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Differential indirect effects of two plant viruses on an invasive and an indigenous whitefly vector: implications for competitive displacement

The role of vector–begomovirus–plant interactions in the widespread invasion by some members of the whitefly species complex Bemisia tabaci is poorly understood. The invasive B biotype of B. tabaci entered China in the late 1990s and had become the predominant or only biotype of the whitefly in many regions of the country by 2005–2006. Meanwhile epidemics of begomoviruses have been observed in many crops including tomato for which Tomato yellow leaf curl China virus (TYLCCNV) and Tomato yellow leaf curl virus (TYLCV) have been identified as two major disease-causing agents. Here, we conducted laboratory experiments to compare the performance of the invasive B and indigenous ZHJ1 whitefly biotypes on uninfected, TYLCCNV-infected and TYLCV-infected plants of tomato cv. Hezuo903, a cultivar that has been widely cultivated in many regions of China. The infection of tomato plants by either of the viruses had no or only marginal effects on the development, survival and fecundity of the B biotype. In contrast, survival and fecundity of the ZHJ1 biotype were significantly reduced on virus-infected plants compared to those on uninfected plants. Populations of the B biotype on uninfected and TYLCCNV-infected plants increased at similar rates, whereas population increase of the ZHJ1 biotype on TYLCCNV-infected plants was affected adversely. These asymmetric responses to virus infection of tomato plants between the B and ZHJ1 biotypes are likely to offer advantages to the B biotype in its invasion and displacement of the indigenous biotype.     

Low frequency of horizontal and vertical transmission of two begomoviruses through whiteflies exhibits little relevance to the vector infectivity

Transmissions of plant viruses between individuals of their vector insects through mating are rare events. Recently, three begomoviruses were found to be transmitted between males and females of the whitefly Bemisia tabaci through mating, and two viruses were shown to be transmitted transovarially to progeny. However, results between reports were not consistent. Here we examined the horizontal and vertical transmission of Tomato yellow leaf curl virus (TYLCV) and Tomato yellow leaf curl China virus (TYLCCNV) by the B and Q biotypes of B. tabaci, using virus isolates and whitefly colonies established recently in China. Both TYLCV DNA and TYLCCNV DNA were shown to be transmitted horizontally and vertically by each of the two biotypes of the whitefly, but frequency of transmission was usually low. In transovarial transmission, virus DNA was detected in eggs and nymphs but not in the adults of the first generation progeny, except in the combination of TYLCV and Q biotype whitefly where 2–3% of the offspring adults contained the virus DNA. We also showed that the first generation adults, which developed from eggs of viruliferous whiteflies, were not infective to plants. These results demonstrated that for the viruses and whiteflies tested here low frequency of horizontal and vertical transmission can be expected but these two modes of transmission are unlikely to have much epidemiological relevance in the field.     

烟粉虱传播双生病毒研究进展

综述了烟粉虱Bemisia tabaci对双生病毒的获取、传播及存留等方面的特性。烟粉虱最短的获毒和接种时间为15～30 min;双生病毒在烟粉虱体内可存留1至数周,有的终身存在。烟粉虱对双生病毒的传毒效率除了随其获毒及传毒时间的延长、传毒烟粉虱个体数量的增加以及病毒体浓度的增加而提高外,还与烟粉虱的龄期及性别有关。双生病毒除了在植物与粉虱之间直接传播外,还可通过烟粉虱交配及经卵携带的途径在烟粉虱个体和代别间进行传播。寄主植物、双生病毒的一些特殊蛋白以及烟粉虱内共生菌产生的GroEL蛋白,都可影响烟粉虱携带的双生病毒种类及传毒的可能性。双生病毒可对烟粉虱的发育、存活和生殖产生不利或有利的影响。雌成虫携带番茄黄化曲叶病毒（tomato yellow leaf curl virus, TYLCV）后,存活力和生殖力均下降; 而携带番茄斑驳病毒（tomato mottle virus, ToMoV）后,生殖力提高。此外,植物感染双生病毒后,其对烟粉虱的适合性可能提高。     

Host range, vector relations and serological relationships of cotton leaf curl virus from southern India

In 1989 to 1991, leaf curl disease was observed in cotton (Gossypium bar-badense cv. Local) grown in kitchen gardens in five districts in Karnataka State, India, and in 1994 it was recorded in G. hirsutum cv. Sharada in two districts. Symptoms consist of leaf curling, vein thickening, leaf enations, and stunting and distortion of plants. The disease is caused by cotton leaf curl virus (CLCuV-K), which was transmitted by the whitefly Bemisia tabaci to 24 plant species in six families. Hosts include bean (Phaseolus vulgaris), pepper, tobacco, tomato and several weeds, almost all of which developed leaf curl, with or without vein thickening. CLCuV-K was transmitted from cotton to cotton by adult B. tabaci after an acquisition access period of 1 h, could be inoculated in 5 min, had a minimum latent period of 8 h and was retained by viruliferous insects for up to 9 days. Female B. tabaci transmitted more frequently than males. CLCuV-K is a whitefly-transmitted geminivirus. It reacted with two out of 17 monoclonal antibodies (MAbs) raised to African cassava mosaic virus and five out of 10 MAbs raised to Indian cassava mosaic virus. CLCuV-K isolates from different locations in Karnataka had similar epitope profiles. As judged by these profiles, CLCuV-K is closely related to Indian tomato leaf curl virus from Karnataka, is distinguishable from several other whitefly-transmitted geminiviruses found in India and is still more distantly related to those, including cotton leaf crumple virus from the USA, found in other continents. CLCuV-K infected all cultivars tested of G. barbadense and one of six cultivars of G. hirsutum but none of G. arboreum or G. herbaceum.     

Tomato yellow leaf curl virus infection of tomato does not affect the performance of the Q and ZHJ2 biotypes of the viral vector Bemisia tabaci

Abstract To better understand the etiology of begomovirus epidemics in regions under invasion we need to know how indigenous and invasive whitefly vectors respond to virus infection. We investigated both direct and indirect effects of infection with Tomato yellow leaf curl virus (TYLCV) on the performance of the invasive Q biotype and the indigenous Asian ZHJ2 biotype of whitefly Bemisia tabaci. The Q biotype performed better than the ZHJ2 biotype on either uninfected or virus‐infected tomato plants. However, virus‐infection of host plants did not, or only marginally affected, the performance of either biotype of whiteflies in terms of fecundity, longevity, survival, development and population increase. Likewise, association of the vectors with TYLCV did not affect fecundity and longevity of the Q or ZHJ2 biotypes on cotton, a non‐host of TYLCV. These results indicate that the alien Q biotype whitefly, but not the indigenous ZHJ2 biotype, is likely to become the major vector of TYLCV in the field and facilitate virus epidemics.     

Detection and relationships of cotton leaf curl virus and allied whitefly-transmitted geminiviruses occurring in Pakistan

A stock culture of cotton leaf curl virus from Pakistan (CLCuV-PK), was transmitted by whiteflies (Bemisia tabaci) to seven plant species, including French bean, okra, tobacco and tomato, and caused vein thickening and leaf curl symptoms. It was readily detected in triple antibody sandwich ELISA (TAS-ELIS A) by 11 out of 31 monoclonal antibodies raised against the particles of three other geminiviruses: African cassava mosaic, Indian cassava mosaic and okra leaf curl viruses. Reaction strength was enhanced when the tissue extraction fluid contained sodium sulphite. Minor variations in epitope profile were found among virus isolates from cotton (Gossypium hirsutum) collected from different districts in Pakistan over a 5-year period. These epitope profiles were distinguishable from that of cotton leaf curl virus from G. barbadense in southern India but indistinguishable from the profiles of viruses causing yellow vein disease of okra in India or Pakistan, or leaf curl of okra {Abelmoschus esculentus), Hibiscus tiliaceus, radish or sunflower in Pakistan, suggesting that these plants are putative natural hosts of CLCuV-PK. The viruses in cotton, and in okra with leaf curl or yellow vein symptoms, were also detected by PCR with three pairs of CLCuV-PK-specific primers. Five additional whitefly-transmitted geminiviruses were found among isolates from 11 other naturally-infected species in Pakistan, and were distinguished by their epitope profiles. These viruses were associated, respectively, with tobacco leaf curl, squash yellow blotch, tomato yellow leaf curl, watermelon leaf crinkle and soybean yellow mosaic diseases. The first four of these viruses were detected readily by PCR with geminivirus general primers but only weakly, if at all, with two pairs of CLCuV-PK-specific primers. Pakistani crops are infected with a range of distinguishable but relatively closely related whitefly-transmitted geminiviruses, some of which resemble those found in India.     

Patterns of host cell inheritance in the bacterial symbiosis of whiteflies

Whiteflies possess bacterial symbionts Candidatus Portiera aleyrodidium that are housed in specialized cells called bacteriocytes and are faithfully transmitted via the ovary to insect offspring. In one whitefly species studied previously, Bemisia tabaci MEAM1, transmission is mediated by somatic inheritance of bacteriocytes, with a single bacteriocyte transferred to each oocyte and persisting through embryogenesis to the next generation. Here, we investigate the mode of bacteriocyte transmission in two whitefly species, B. tabaci MED, the sister species of MEAM1, and the phylogenetically distant species Trialeurodes vaporariorum. Microsatellite analysis supported by microscopical studies demonstrates that B. tabaci MED bacteriocytes are genetically different from other somatic cells and persist through embryogenesis, as for MEAM1, but T. vaporariorum bacteriocytes are genetically identical to other somatic cells of the insect, likely mediated by the degradation of maternal bacteriocytes in the embryo. These two alternative modes of transmission provide a first demonstration among insect symbioses that the cellular processes underlying vertical transmission of bacterial symbionts can diversify among related host species associated with a single lineage of symbiotic bacteria.     

The circulative pathway of begomoviruses in the whitefly vector Bemisia tabaci— insights from studies with Tomato yellow leaf curl virus

Our current knowledge concerning the transmission of begomoviruses by the whitefly vector Bemisia tabaci is based mainly on research performed on the Tomato yellow leaf curl virus (TYLCV) complex and on a number of viruses originating from the Old World, such as Tomato leaf curl virus, and from the New World, including Abutilon mosaic virus, Tomato mottle virus, and Squash leaf curl virus. In this review we discuss the characteristics of acquisition, transmission and retention of begomoviruses by the whitefly vector, concentrating on the TYLCV complex, based on both published and recent unpublished data. We describe the cells and organs encountered by begomoviruses in B. tabaci. We show immunolocalisation of TYLCV to the B. tabaci stylet food canal and to the proximal part of the descending midgut, and TYLCV‐specific labelling was also associated with food in the lumen. The microvilli and electron‐dense material in the epithelial cells of the gut wall were also labelled by the anti TYLCV serum, pointing to a possible virus translocation route through the gut wall and to a putative site of long‐term virus storage. We describe the path of begomoviruses in their vector B. tabaci and in the non‐vector whitefly Trialeurodes vaporariorum, and we follow the rate of virus translocation in these insects. We discuss TYLCV transmission between B. tabaci during mating, probably by exchange of haemolymph. We show that following a short acquisition access to infected tomato plants, TYLCV remains associated with the B. tabaci vector for weeks, while the virus is undetectable after a few hours in the non‐vector T. vaporariorum. The implications of the long‐term association of TYLCV with B. tabaci in the light of interactions of the begomovirus with insect receptors are discussed.     

Virus–vector Relationships,Host Range,Detection and Sequence Comparison of Chilli leaf curl virus Associated with an Epidemic of Leaf Curl Disease of Chilli in Jodhpur,India

An epidemic of chilli leaf curl disease was recorded in 2004 in Jodhpur, a major chilli‐growing area in Rajasthan, India. Several isolates were efficiently transmitted by the whitefly (Bemisia tabaci), all of which induced severe leaf curl symptoms in chilli. A single whitefly was capable of transmitting the virus, and eight or more whiteflies per plant resulted in 100% transmission. The minimum acquisition access period (AAP) and inoculation access period (IAP) were 180 and 60 min, respectively. The virus persisted in whiteflies for up to 5 days postacquisition. Of 25 species tested, the virus infected only five (Capsicum annuum, Carica papaya, Solanum lycopersicum, Nicotiana tabacum and N. benthamiana). The virus was identified as Chilli leaf curl virus (ChiLCV), which shared the closest sequence identity (96.1%) with an isolate of ChiLCV from potato in Pakistan and showed sequence diversity up to 12.3% among the ChiLCV isolates reported from India and Pakistan. A betasatellite was identified, which resembled most closely (97.3%) that of Tomato leaf curl Bangladesh betasatellite previously reported from chilli and tomato leaf curl in India. The betasatellite was very different from that reported from chilli leaf curl in Pakistan, indicating that different betasatellites are associated with chilli leaf curl in India and Pakistan. We describe here for the first time the virus–vector relationships and host range of ChiLCV.     

A virus and its vector,pepper yellow leaf curl virus and <Emphasis Type="Italic">Bemisia tabaci</Emphasis>, two new invaders of Indonesia

Bemisia tabaci is a species of sap-sucking insect belonging to the Aleyrodidae and are commonly known as whiteflies. The species is made up of a complex of distinct genetic groups which have a strong geographic pattern to their genetic structure. Two members of this complex known as the B and Q biotypes have proven to be particularly invasive, spreading with the aid of trade in ornamental plants, well beyond their home ranges across the Mediterranean Basin, Middle East and Asia Minor. This study uses DNA microsatellites to identify another biological invasion this time involving a B. tabaci from south east Asia. We provide evidence which supports an invasion sometime between 1994 and 1999 of B. tabaci from central Thailand into the Indonesian islands of Sumatra then Java and Bali. The invasion is also associated with the invasion of pepper yellow leaf curl virus, a begomovirus transmitted by B. tabaci, which is also shown to have a probable origin in the same geographic region as the invading whitefly. The consequences of the invasion of a plant-infecting virus and its vector has been a massive increase in the scale and impact of begomoviruses in tomato and chilli production which has seen regional bans imposed on the planting of chilli, an important cash crop for many village farmers in Sumatra and Java.     

Incidences and progression of tomato chlorosis virus disease and tomato yellow leaf curl virus disease in tomato under different greenhouse covers in southeast Spain

Epidemics of whitefly‐transmitted Tomato chlorosis virus, Tomato yellow leaf curl Sardinia virus and Tomato yellow leaf curl virus have been present in the south east of Spain since the 1990s. A survey was performed in 40 greenhouses and nethouses during 2003 to establish the relationship between the disease incidence and the quality of greenhouse or nethouse coverings, providing a physical protection of crops against whiteflies. For tomato chlorosis virus disease (ToCD), the incidence correlated with the type of greenhouse cover and was most reduced under higher quality covers. Control of tomato yellow leaf curl disease (TYLCD) was achieved only for crops grown in the highest quality greenhouses. TYLCD incidence in tolerant tomatoes remained below 100% within the 5 months of sampling, despite the disease progress rate at the initial stage of the cultivation being higher than that of ToCD, which did reach 100% incidence in many greenhouses. Linear regression analysis showed that the development of ToCD and TYLCD in most of the greenhouses was best described by the monomolecular model and the Gompertz model, respectively. Tomato infectious chlorosis virus was not detected in parallel surveys carried out during this study, although it has been described previously in the area studied.     

Occurrence of whitefly-transmitted geminiviruses in crops in Burkina Faso, and their serological detection and differentiation

Whitefly-transmitted geminiviruses were found to be associated with four diseases of crop plants in Burkina Faso: cassava mosaic, okra leaf curl, tobacco leaf curl and tomato yellow leaf curl. Tomato yellow leaf curl is an economically serious disease, reaching a high incidence in March, following a peak population of the vector whitefly, Bemisia tabaci, in December. Okra leaf curl is also a problem in the small area of okra grown in the dry season but is not important in the main period of okra production in the rainy season. The geminiviruses causing these four diseases, African cassava mosaic (ACMV), okra leaf curl (OLCV), tobacco leaf curl (TobLCV) and tomato yellow leaf curl (TYLCV) viruses, were each detected in field-collected samples by triple antibody sand-wich-ELISA with cross-reacting monoclonal antibodies (MAbs) to ACMV. Epitope profiles obtained by testing each virus isolate with panels of MAbs to ACMV, OLCV and Indian cassava mosaic virus enabled four viruses to be distinguished. ACMV and OLCV had similar but distinguishable profiles. The epitope profile of TobLCV was the same as that of one form of TYLCV (which may be the same virus) and was close to the profile of TYLCV from Sardinia. The other form of TYLCV reacted with several additional MAbs and had an epitope profile close to that of TYLCV from Senegal. Only minor variations within each of these four types of epitope profile were found among geminivirus isolates from Burkina Faso. Sida acuta is a wild host of OLCV.