“Cross-protection”, a nearly 100 years-old virological term, is suggested to be changed to “close protection”. Evidence for the need of such change has accumulated over the past six decades from the laboratory experiments and field tests conducted by plant pathologists and plant virologists working with different plant viruses, and, in particular, from research on Citrus tristeza virus (CTV). A direct confirmation of such close protection came with the finding that “pre-immunization” of citrus plants with the variants of the T36 strain of CTV but not with variants of other virus strains was providing protection against a fluorescent protein-tagged T36-based recombinant virus variant. Under natural conditions close protection is functional and is closely associated both with the conservation of the CTV genome sequence and prevention of superinfection by closely similar isolates. It is suggested that the mechanism is primarily directed to prevent the danger of virus population collapse that could be expected to result through quasispecies divergence of large RNA genomes of the CTV variants continuously replicating within long-living and highly voluminous fruit trees. This review article provides an overview of the CTV cross-protection research, along with a discussion of the phenomenon in the context of the CTV biology and genetics.

中文翻译：

---

走在一起：交叉保护，基因组保存和柑橘柑橘的复制机制。

建议将“交叉保护”这个已有近100年历史的病毒学术语改为“紧密保护”。在过去的六十年中，由从事不同植物病毒工作的植物病理学家和植物病毒学家进行的实验室实验和田间试验，尤其是对柑橘柑桔病毒的研究，积累了需要进行此类改变的证据。（CTV）。这种紧密保护的直接证实来自以下发现：用CTV T36株的变体而不是其他病毒株的变体对柑橘类植物进行“预免疫”提供了针对基于荧光蛋白标签的基于T36的重组体的保护病毒变体。在自然条件下，严密保护是功能性的，并且与CTV基因组序列的保守性和通过密切相似的分离物防止过度感染密切相关。建议该机制主要是为了防止病毒种群崩溃的危险，而这种危险可能是由于在长寿和高果树上连续复制的CTV变异体的大型RNA基因组的准种差异导致的。