The recent introduction of maize chlorotic mottle virus (MCMV) and spread of the resulting maize lethal necrosis disease (MLN) in East Africa presents a threat to maize production in all Southern African countries. As MLND is the result of the synergistic action of MCMV and various cereal-infecting potyviruses, the existing virus status of maize in KwaZulu-Natal, a province of South Africa bordering Mozambique and Eswatini, was determined. Additional viruses identified in MLND affected plants in East Africa previously were also tested for in this study, including maize streak virus (MSV), Morogoro maize-associated virus (MMaV), maize-associated pteridovirus (MaPV), and two maize-associated totivirus (MATV) variants. No MCMV or potyvirus infections were detected. MSV was identified in 29% of the pools (consisting of five plants each), MaPV was detected in three plants, while only a single plant tested positive for MMaV. The presence of MMaV and MaPV was confirmed with next generation sequencing (NGS) and their complete/near complete genome sequences assembled. MMaV was also further confirmed with additional PCR primer sets. This is the first time MMaV and MaPV have been reported in South Africa. Two distinct MATV variants and two Zea mays chrysovirus 1 strains were also detected using NGS but no further tests were conducted, hence, these findings remain preliminary. Future research is required to determine the incidence and distribution of these new viruses in South Africa, their mode(s) of transmission, and effects on maize yield to determine the possible risk they may pose to the South African maize industry.

玉米绿叶斑驳病毒（MCMV）的最新引入以及由此产生的玉米致死性坏死病（MLN）在东非的传播，对所有南部非洲国家的玉米生产构成了威胁。由于MLND是MCMV与多种谷物感染性马铃薯病毒协同作用的结果，因此确定了南非与莫桑比克和埃斯瓦蒂尼接壤的南非夸祖鲁-纳塔尔省玉米的现有病毒状况。先前在东非受MLND影响的植物中鉴定出的其他病毒也进行了此项研究的测试，包括玉米条纹病毒（MSV），莫罗哥罗玉米相关病毒（MMaV），玉米相关蕨类病毒（MaPV）和两种玉米相关Totivirus （MATV）变体。未检测到MCMV或杯状病毒感染。在29％的池中（每个由五株植物组成）鉴定出MSV，在三株植物中检测到了MaPV，而只有一株植物的MMaV检测呈阳性。下一代测序（NGS）证实了MMaV和MaPV的存在，并组装了它们的完整/接近完整的基因组序列。还用其他PCR引物组进一步证实了MMaV。这是南非首次报告MMaV和MaPV。两个不同的MATV变体和两个还使用NGS检测到了玉米黄热病毒1株，但没有进行进一步的测试，因此，这些发现仍然是初步的。需要进一步的研究来确定这些新病毒在南非的发病率和分布，它们的传播方式以及对玉米产量的影响，以确定它们可能对南非玉米产业构成的潜在风险。