Polymorphisms in Human Cytomegalovirus Glycoprotein O (gO) Exert Epistatic Influences on Cell-Free and Cell-to-Cell Spread and Antibody Neutralization on gH Epitopes
Polymorphisms in Human Cytomegalovirus Glycoprotein O (gO) Exert Epistatic Influences on Cell-Free and Cell-to-Cell Spread and Antibody Neutralization on gH Epitopes
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DOI：
10.1128/jvi.02051-19
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发表时间：
2020-04-01
影响因子：
5.4
通讯作者：
Ryckman, Brent J.
中科院分区：
文献类型：
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作者：
Day, Le Zhang;Stegmann, Cora;Ryckman, Brent J.
人巨细胞病毒糖蛋白H和L(Gh/g1)可与GO或UL128与UL131蛋白(简称UL128-131)结合形成便于进入和扩散的复合体，该复合体是中和抗体的重要靶点。HCMV毒株的Gh/gl/Go和Gh/gl/UL128-131水平差异很大，这会影响感染性和细胞嗜性。在这项研究中，我们研究了GO氨基酸序列的自然株间变异如何影响HCMV的生物学特性。构建了异源GO重组体，其中GO的8个等位基因或基因类型(GT)中的6个在菌株TR和Merlin(ME)的背景下进行了分析。Gh/Gl复合体的水平不受影响，但对抗Gh抗体进入、扩散和中和有影响。AD169(AD)GO(GT1a)[这里称为AdGO(GT1a)]显著降低了这两种菌株对成纤维细胞和上皮细胞的无细胞感染力。PHgO(GT2a)在两种细胞中都增加了TR的无细胞感染性，但在成纤维细胞中的传播受到抑制。相反，Towne(TN)G0(GT4)促进了ME在两种细胞类型中的传播，尽管它们的无细胞感染性相似。TnGO(GT4)能抵抗抗GH抗体AP86和14-4b的中和，而Adgo(GT1a)能抵抗14-4b，但能增强AP86的中和作用。反之，表达Adgo(GT1a)的ME对14-4b的抗性更强。这些结果表明：(1)Gh/Gl/Go在病毒的无细胞传播和细胞间传播中起着不同的作用；(2)Go亚型可以不同程度地保护病毒免受中和抗体的侵袭；(3)Go基因多态的作用依赖于其他变量。此外，不同基因类型之间的重组可能会将可变基因座改组为各种组合，结果未知。UL74(Go)是HCMV感染性的重要决定因素，也是病毒基因组中最具多样性的基因座之一。通过对株间异源UL74(GO)重组体的分析，我们发现GO多样性可以对细胞外传播和细胞间传播以及抗体中和产生显著影响，这些影响的表现可能受到全球遗传背景的上位性影响。这些结果突显了使用单一、分离的基因型或毒株的巨细胞病毒生物学实验室研究的潜在局限性。
Human cytomegalovirus (HCMV) glycoproteins H and L (gH/gL) can be bound by either gO or the UL128 to UL131 proteins (referred to here as UL128-131) to form complexes that facilitate entry and spread, and the complexes formed are important targets of neutralizing antibodies. Strains of HCMV vary considerably in the levels of gH/gL/gO and gH/gL/UL128-131, and this can impact infectivity and cell tropism. In this study, we investigated how natural interstrain variation in the amino acid sequence of gO influences the biology of HCMV. Heterologous gO recombinants were constructed in which 6 of the 8 alleles or genotypes (GT) of gO were analyzed in the backgrounds of strains TR and Merlin (ME). The levels of gH/gL complexes were not affected, but there were impacts on entry, spread, and neutralization by anti-gH antibodies. AD169 (AD) gO (GT1a) [referred to here as ADgO(GT1a)) drastically reduced cell-free infectivity of both strains on fibroblasts and epithelial cells. PHgO(GT2a) increased cell-free infectivity of TR in both cell types, but spread in fibroblasts was impaired. In contrast, spread of ME in both cell types was enhanced by Towne (TN) g0 (GT4), despite similar cell-free infectivity. TR expressing TNgO(GT4) was resistant to neutralization by anti-gH antibodies AP86 and 14-4b, whereas ADgO(GT1a) conferred resistance to 14-4b but enhanced neutralization by AP86. Conversely, ME expressing ADgO(GT1a) was more resistant to 14-4b. These results suggest that (i) there are mechanistically distinct roles for gH/gL/gO in cell-free and cell-to-cell spread, (ii) gO isoforms can differentially shield the virus from neutralizing antibodies, and (iii) effects of gO polymorphisms are epistatically dependent on other variable loci.IMPORTANCE Advances in HCMV population genetics have greatly outpaced understanding of the links between genetic diversity and phenotypic variation. Moreover, recombination between genotypes may shuffle variable loci into various combinations with unknown outcomes. UL74(gO) is an important determinant of HCMV infectivity and one of the most diverse loci in the viral genome. By analyzing interstrain heterologous UL74(gO) recombinants, we showed that gO diversity can have dramatic impacts on cell-free and cell-to-cell spread as well as on antibody neutralization and that the manifestation of these impacts can be subject to epistatic influences of the global genetic background. These results highlight the potential limitations of laboratory studies of HCMV biology that use single, isolated genotypes or strains.