Ogbe F O, Atiri G I, Robinson D, Winter S, Dixon A G O, Quin F M, Thottappilly G
International Institute of Tropical Agriculture (IITA), P.M.B. 5320, Ibadan, Nigeria.
Department of Crop Protection and Environmental Biology, University of Ibadan, Nigeria.
Plant Dis. 1999 Apr;83(4):398. doi: 10.1094/PDIS.1999.83.4.398A.
Cassava (Manihot esculenta Crantz) is an important food crop in sub-Saharan Africa. One of the major production constraints is cassava mosaic disease caused by African cassava mosaic (ACMV) and East African cassava mosaic (EACMV) begomoviruses. ACMV is widespread in its distribution, occurring throughout West and Central Africa and in some eastern and southern African countries. In contrast, EACMV has been reported to occur mainly in more easterly areas, particularly in coastal Kenya and Tanzania, Malawi, and Madagascar. In 1997, a survey was conducted in Nigeria to determine the distribution of ACMV and its strains. Samples from 225 cassava plants showing mosaic symptoms were tested with ACMV monoclonal antibodies (MAbs) in triple antibody sandwich enzyme-linked immunosorbent assay (1). Three samples reacted strongly with MAbs that could detect both ACMV and EACMV. One of them did not react with ACMV-specific MAbs while the other two reacted weakly with such MAbs. With polymerase chain reaction (2), the presence of EACMV and a mixture of EACMV and ACMV in the respective samples was confirmed. These samples were collected from two villages: Ogbena in Kwara State and Akamkpa in Cross River State. Co-infection of some cassava varieties with ACMV and EACMV leads to severe symptoms. More importantly, a strain of mosaic geminivirus known as Uganda variant arose from recombination between the two viruses (2). This report provides evidence for the presence of EACMV in West Africa. References: (1) J. E. Thomas et al. J. Gen. Virol. 67:2739, 1986. (2) X. Zhou et al. J. Gen. Virol. 78:2101, 1997.
木薯（Manihot esculenta Crantz）是撒哈拉以南非洲地区的一种重要粮食作物。主要生产限制因素之一是由非洲木薯花叶病毒（ACMV）和东非木薯花叶病毒（EACMV）引起的木薯花叶病。ACMV分布广泛，在西非和中非以及一些东部和南部非洲国家均有发生。相比之下，据报道EACMV主要发生在更偏东的地区，特别是在肯尼亚和坦桑尼亚沿海、马拉维和马达加斯加。1997年，在尼日利亚进行了一项调查，以确定ACMV及其毒株的分布情况。在三重抗体夹心酶联免疫吸附试验中，用ACMV单克隆抗体（MAbs）对225株表现出花叶症状的木薯植株样本进行了检测（1）。三个样本与能同时检测ACMV和EACMV的MAbs发生强烈反应。其中一个样本与ACMV特异性MAbs不发生反应，而另外两个样本与这类MAbs反应较弱。通过聚合酶链反应（2），证实了相应样本中存在EACMV以及EACMV和ACMV的混合物。这些样本采自两个村庄：夸拉州的奥格贝纳和克罗斯河州的阿卡姆帕。一些木薯品种同时感染ACMV和EACMV会导致严重症状。更重要的是，两种病毒之间的重组产生了一种名为乌干达变种的花叶双生病毒毒株（2）。本报告为EACMV在西非的存在提供了证据。参考文献：（1）J. E. Thomas等人，《病毒学杂志》67:2739，1986年。（2）X. Zhou等人，《病毒学杂志》78:2101，1997年。
