Cytomegaloviruses (CMVs) are highly adapted to their host species resulting in strict species specificity. Hence, in vivo examination of all aspects of CMV biology employs animal models using host-specific CMVs. Infection of rhesus macaques (RM) with rhesus CMV (RhCMV) has been established as a representative model for infection of humans with HCMV due to the close evolutionary relationships of both host and virus. However, the commonly used 68-1 strain of RhCMV has been passaged in fibroblasts for decades resulting in multiple genomic changes due to tissue culture adaptation that cause reduced viremia in RhCMV-naïve animals and limited shedding compared to low passage isolates. Using sequence information from primary RhCMV isolates we constructed a full-length (FL) RhCMV by repairing all presumed mutations in the 68-1 bacterial artificial chromosome (BAC). Inoculation of adult, immunocompetent, RhCMV-naïve RM with the reconstituted virus resulted in significant replication in the blood similar to primary isolates of RhCMV and furthermore led to extensive viremia in many tissues at day 14 post infection. In contrast, viral dissemination and viremia was greatly reduced upon deletion of genes also lacking in 68-1. Transcriptome analysis of infected tissues further revealed that chemokine-like genes deleted in 68-1 are among the most highly expressed viral transcripts both in vitro and in vivo consistent with an important immunomodulatory function of the respective proteins. We conclude that FL-RhCMV displays in vitro and in vivo characteristics of a wildtype virus while being amenable to genetic modifications through BAC recombineering techniques.

中文翻译：

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含有完整基因组的重组恒河猴巨细胞病毒的体外和体内表征

巨细胞病毒（CMV）高度适应其宿主物种，因此具有严格的物种特异性。因此，CMV生物学所有方面的体内检查均采用动物模型，使用宿主特异性CMV。由于宿主和病毒之间的密切进化关系，已经建立了以恒河猴CMV（RhCMV）感染恒河猴（RM）作为人类感染HCMV的代表性模型。然而，常用的68-1株RhCMV菌株已经在成纤维细胞中传代了数十年，这是由于组织培养适应性导致了多种基因组变化，与低传代分离株相比，这种培养可降低纯天然RhCMV动物的病毒血症并减少脱落。使用来自主要RhCMV分离株的序列信息，我们通过修复68-1细菌人工染色体（BAC）中所有假定的突变，构建了全长（FL）RhCMV。用重组病毒接种成人，具有免疫能力的RhCMV幼稚RM会导致血液中的大量复制，类似于RhCMV的主要分离株，而且在感染后第14天导致许多组织中出现大量病毒血症。相比之下，删除同样缺乏68-1的基因后，病毒的传播和病毒血症大大减少。感染组织的转录组分析进一步表明，在68-1中缺失的趋化因子样基因是体外和体内表达最强的病毒转录物之一，与相应蛋白质的重要​​免疫调节功能相一致。