Bera Sayanta, Moreno-Pérez Manuel G, García-Figuera Sara, Pagán Israel, Fraile Aurora, Pacios Luis F, García-Arenal Fernando
Centro de Biotecnología y Genómica de Plantas and Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Campus de Montegancedo, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain.
Centro de Biotecnología y Genómica de Plantas and Escuela Técnica Superior de Ingenieros de Montes, Campus de Montegancedo, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain.
J Virol. 2017 Aug 24;91(18). doi: 10.1128/JVI.00435-17. Print 2017 Sep 15.
In gene-for-gene host-virus interactions, virus evolution to infect and multiply in previously resistant host genotypes, i.e., resistance breaking, is a case of host range expansion, which is predicted to be associated with fitness penalties. Negative effects of resistance-breaking mutations on within-host virus multiplication have been documented for several plant viruses. However, understanding virus evolution requires analyses of potential trade-offs between different fitness components. Here we analyzed whether coat protein (CP) mutations in that break -gene resistance in pepper affect particle stability and, thus, survival in the environment. For this purpose, CP mutations determining the overcoming of and resistance alleles were introduced in biologically active cDNA clones. The kinetics of the disassembly of parental and mutant particles were compared under different conditions. Resistance-breaking mutations variously affected particle stability. Structural analyses identified the number and type of axial and side interactions of adjacent CP subunits in virions, which explained differences in particle stability and contribute to understanding of tobamovirus disassembly. Resistance-breaking mutations also affected virus multiplication and virulence in the susceptible host, as well as infectivity. The sense and magnitude of the effects of resistance-breaking mutations on particle stability, multiplication, virulence, or infectivity depended on the specific mutation rather than on the ability to overcome the different resistance alleles, and effects on different traits were not correlated. Thus, the results do not provide evidence of links or trade-offs between particle stability, i.e., survival, and other components of virus fitness or virulence. The effect of survival on virus evolution remains underexplored, despite the fact that life history trade-offs may constrain virus evolution. We approached this topic by analyzing whether breaking of -gene resistance in pepper by , determined by coat protein (CP) mutations, is associated with reduced particle stability and survival. Resistance-breaking mutations affected particle stability by altering the interactions between CP subunits. However, the sense and magnitude of these effects were unrelated to the capacity to overcome different resistance alleles. Thus, resistance breaking was not traded with survival. Resistance-breaking mutations also affected virus fitness within the infected host, virulence, and infectivity in a mutation-specific manner. Comparison of the effects of CP mutations on these various traits indicates that there are neither trade-offs nor positive links between survival and other life history traits. These results demonstrate that trade-offs between life history traits may not be a general constraint in virus evolution.
在基因对基因的宿主 - 病毒相互作用中，病毒进化以在先前具有抗性的宿主基因型中感染和繁殖，即抗性突破，是宿主范围扩展的一种情况，预计与适应性代价相关。几种植物病毒已记录到抗性突破突变对宿主体内病毒繁殖的负面影响。然而，了解病毒进化需要分析不同适应性成分之间潜在的权衡。在这里，我们分析了辣椒中打破基因抗性的外壳蛋白（CP）突变是否会影响颗粒稳定性，进而影响其在环境中的存活。为此，将决定克服抗性等位基因的CP突变引入具有生物活性的cDNA克隆中。在不同条件下比较了亲本颗粒和突变颗粒的解体动力学。抗性突破突变对颗粒稳定性有不同影响。结构分析确定了病毒粒子中相邻CP亚基轴向和侧向相互作用的数量和类型，这解释了颗粒稳定性的差异，并有助于理解烟草花叶病毒的解体。抗性突破突变还影响了易感宿主中的病毒繁殖、毒力以及感染力。抗性突破突变对颗粒稳定性、繁殖、毒力或感染力的影响方向和程度取决于具体突变，而非克服不同抗性等位基因的能力，并且对不同性状的影响不相关。因此，结果并未提供颗粒稳定性（即存活）与病毒适应性或毒力的其他成分之间存在联系或权衡的证据。尽管生活史权衡可能会限制病毒进化，但存活对病毒进化的影响仍未得到充分研究。我们通过分析由外壳蛋白（CP）突变决定的辣椒中基因抗性的突破是否与颗粒稳定性降低和存活减少相关来探讨这个话题。抗性突破突变通过改变CP亚基之间的相互作用影响颗粒稳定性。然而，这些影响的方向和程度与克服不同抗性等位基因的能力无关。因此，抗性突破与存活之间不存在权衡。抗性突破突变还以突变特异性方式影响受感染宿主体内的病毒适应性、毒力和感染力。比较CP突变对这些不同性状的影响表明，存活与其他生活史性状之间既不存在权衡也不存在正向联系。这些结果表明，生活史性状之间的权衡可能不是病毒进化的普遍限制因素。
