Zhao Kaixi, Rosa Cristina
Department of Plant Pathology and Environmental Microbiology, The Pennsylvania State University, University Park, PA 16802, USA.
Plants (Basel). 2020 Apr 15;9(4):509. doi: 10.3390/plants9040509.
Mixed infections provide opportunities for viruses to increase genetic diversity by facilitating genomic reassortment or recombination, and they may lead to the emergence of new virus species. Mixed infections of two economically important orthotospoviruses, Tomato spotted wilt orthotospovirus (TSWV) and Impatiens necrotic spot orthotospovirus (INSV), were found in recent years, but no natural reassortants between INSV and TSWV were ever reported. The goal of this study was to establish how vector preferences and the ability to transmit INSV and TSWV influence transmission and establishment of mixed infections. Our results demonstrate that thrips prefer to oviposit on TSWV and INSV mixed-infected plants over singly infected or healthy plants, providing young nymphs with the opportunity to acquire both viruses. Conversely, we observed that thrips served as a bottleneck during transmission and favored transmission of one of the two viruses over the second one, or over transmission of both viruses simultaneously. This constraint was relaxed in plants, when transmission of TSWV and INSV occurred sequentially, demonstrating that plants serve as orthotospovirus permissive hosts, while thrips serve as a bottleneck. Viral fitness, as measured by virus replication, transmission, and competition with other viral strains, is not well studied in mixed infection. Our study looks at the success of transmission during mixed infection of orthotopoviruses, enhancing the understanding of orthotospovirus epidemiology and evolution.
混合感染为病毒通过促进基因组重配或重组来增加遗传多样性提供了机会，并且可能导致新病毒种类的出现。近年来发现了两种具有经济重要性的正番茄斑萎病毒属病毒，即番茄斑萎正番茄斑萎病毒（TSWV）和凤仙花坏死斑正番茄斑萎病毒（INSV）的混合感染，但从未有过关于INSV和TSWV之间自然重配体的报道。本研究的目的是确定传毒介体偏好以及传播INSV和TSWV的能力如何影响混合感染的传播和建立。我们的结果表明，蓟马更喜欢在TSWV和INSV混合感染的植株上产卵，而不是在单独感染或健康的植株上，这为若虫提供了同时获取两种病毒的机会。相反，我们观察到蓟马在传播过程中起到了瓶颈作用，更倾向于传播两种病毒中的一种，而不是同时传播两种病毒。当TSWV和INSV的传播依次发生时，这种限制在植株中得到缓解，这表明植株是正番茄斑萎病毒属病毒的允许宿主，而蓟马起到了瓶颈作用。在混合感染中，通过病毒复制、传播以及与其他病毒株系竞争来衡量的病毒适合度尚未得到充分研究。我们的研究关注正番茄斑萎病毒属病毒混合感染期间的传播成功情况，增进了对正番茄斑萎病毒属病毒流行病学和进化的理解。
