The Rachel and Selim Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Viruses. 2019 Apr 30;11(5):404. doi: 10.3390/v11050404.
Viruses are the most prevalent infectious agents, populating almost every ecosystem on earth. Most viruses carry only a handful of genes supporting their replication and the production of capsids. It came as a great surprise in 2003 when the first giant virus was discovered and found to have a >1 Mbp genome encoding almost a thousand proteins. Following this first discovery, dozens of giant virus strains across several viral families have been reported. Here, we provide an updated quantitative and qualitative view on giant viruses and elaborate on their shared and variable features. We review the complexity of giant viral proteomes, which include functions traditionally associated only with cellular organisms. These unprecedented functions include components of the translation machinery, DNA maintenance, and metabolic enzymes. We discuss the possible underlying evolutionary processes and mechanisms that might have shaped the diversity of giant viruses and their genomes, highlighting their remarkable capacity to hijack genes and genomic sequences from their hosts and environments. This leads us to examine prominent theories regarding the origin of giant viruses. Finally, we present the emerging ecological view of giant viruses, found across widespread habitats and ecological systems, with respect to the environment and human health.
病毒是最普遍的感染性因子，几乎存在于地球上的每一个生态系统中。大多数病毒只携带少数基因来支持其复制和衣壳的生成。2003 年首次发现巨型病毒时，人们感到非常惊讶，因为它的基因组超过 1000 万碱基对，编码了近千种蛋白质。在这一首次发现之后，已经报道了数十种属于不同病毒家族的巨型病毒株。在这里，我们提供了一个关于巨型病毒的更新的定量和定性的观点，并详细阐述了它们的共有和可变特征。我们回顾了巨型病毒蛋白组的复杂性，其中包括传统上仅与细胞生物相关的功能。这些前所未有的功能包括翻译机制、DNA 维持和代谢酶的组成部分。我们讨论了可能塑造巨型病毒及其基因组多样性的潜在进化过程和机制，并强调了它们从宿主和环境中劫持基因和基因组序列的惊人能力。这使我们审视了关于巨型病毒起源的一些主流理论。最后，我们根据环境和人类健康，提出了巨型病毒在广泛分布的栖息地和生态系统中的新兴生态观点。
