Disruption of the murine gammaherpesvirus 68 M1 open reading frame leads to enhanced reactivation from latency
Disruption of the murine gammaherpesvirus 68 M1 open reading frame leads to enhanced reactivation from latency
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DOI：
10.1128/jvi.74.4.1973-1984.2000
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发表时间：
2000-02-01
影响因子：
5.4
通讯作者：
Speck, SH
中科院分区：
文献类型：
--
作者：
Clambey, ET;Virgin, HW;Speck, SH
鼠γ疱疹病毒68（gamma HV 68，或MHV-68）是一种！用于分析γ疱疹病毒发病机制的遗传上易处理的小动物模型。γ HV 68基因组与其他序列γ疱疹病毒的基因组共线，包含大量保守基因，其中散布着许多推定基因，在其他γ疱疹病毒中没有明确的同源物。这些推定的独特基因之一，M1开放阅读框（ORF），表现出序列同源性的痘病毒丝氨酸蛋白酶抑制剂，SPI-1，以及另一个γ HV 68基因，M3，我们最近已经证明编码大量分泌的趋化因子结合蛋白。为了评估M1 ORF对γ HV 68发病机制的贡献，我们产生了重组γ HV 68，其中M1 ORF已通过靶向插入lacZ表达盒（M1.LacZ）而被破坏。虽然M1.LacZ在组织培养中复制正常，但在免疫活性小鼠和免疫缺陷小鼠中，其在感染后第4天和第9天均表现出脾滴度降低。尽管急性病毒复制水平降低，但M1.LacZ建立了与野生型（wt）γ HV 68相当的潜伏感染，但从潜伏期再激活的效率增加了约5倍。M1.LacZ还在γ干扰素受体（IFN-γ R）缺陷小鼠中引起大弹性动脉的严重血管炎，其频率与wt γ HV 68相当，但不引起IFN-γ R缺陷小鼠的wt γ HV 68感染所观察到的死亡率或脾脏病理学。将M1 ORF序列恢复到M1.LacZ中（M1标记拯救，或M1.MR）表明，体内生长和潜伏期的M1.LacZ表型改变不是由于M1.LacZ基因组中其他位置存在额外突变所致。在M1 ORF（M1 Delta 511）的5'端含有缺失但缺乏LacZ表达盒的第二种M1突变体病毒的产生揭示了用M1.LacZ突变体观察到的相同的潜伏表型。然而，M1 Delta 511在脾脏中的急性病毒复制未减毒。我们的结论是：（i）在γ HV 68感染的IFN-γ R缺陷小鼠中，动脉炎的诱导可以在没有脾脏病理和死亡的情况下发生，（ii）急性感染期间的复制不是建立潜伏感染的主要决定因素，（iii）M1 ORF或紧密连锁的基因编码一种基因产物，其功能是抑制病毒再活化。
Murine gammaherpesvirus 68 (gamma HV68, or MHV-68) is a! genetically tractable, small animal model for the analysis of gammaherpesvirus pathogenesis. The gamma HV68 genome is colinear with the genomes of other sequence gammaherpesviruses, containing large blocks of conserved genes interspersed by a number of putative genes without clear homologs in the other gammaherpesviruses. One of these putative unique genes, the M1 open reading frame (ORF), exhibits sequence homology to a poxvirus serine protease inhibitor, SPI-1, as well as to another gamma HV68 gene, M3, which we have recently shown encodes an abundantly secreted chemokine binding protein. To assess the contribution of the M1 ORF to gamma HV68 pathogenesis, we have generated a recombinant gamma HV68 in which the M1 ORF has been disrupted through targeted insertion of a lacZ expression cassette (M1.LacZ). Although M1.LacZ replicated normally in tissue culture, it exhibited decreased splenic titers at days 4 and 9 postinfection in both immunocompetent and immunodeficient mice. Despite decreased levels of acute virus replication, M1.LacZ established a latent infection comparable to wild-type (wt) gamma HV68, but exhibited an approximately fivefold increase in efficiency of reactivation from latency. M1.LacZ also caused severe vasculitis of the great elastic arteries in gamma interferon receptor (IFN-gamma R)-deficient mice with a frequency comparable to wt gamma HV68, but did not cause the mortality or splenic pathology observed with wt gamma HV68 infection of IFN-gamma R-deficient mice. Restoration of M1 ORF sequences into M1.LacZ (M1 marker rescue, or M1.MR) demonstrated that M1.LacZ phenotypic alterations in growth in vivo and latency were not due to the presence of additional mutations located elsewhere in the M1.LacZ genome. Generation of a second M1 mutant virus containing a deletion at the 5' end of the M1 ORF (M1 Delta 511), but lacking the LacZ expression cassette, revealed the same latency phenotype observed with the M1.LacZ mutant. However, M1 Delta 511 was not attenuated for acute virus replication in the spleen. We conclude that (i) the induction of arteritis in gamma HV68-infected IFN-gamma R-deficient mice cam occur in the absence of splenic pathology and mortality, (ii) replication during acute infection is not the primary determinant for the establishment of latent infection, and (iii) the M1 ORF, or a closely linked gene, encodes a gene product that functions to suppress virus reactivation.