Brehm M, Samaniego L A, Bonneau R H, DeLuca N A, Tevethia S S
Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, 17033, USA.
Virology. 1999 Apr 10;256(2):258-69. doi: 10.1006/viro.1999.9653.
Replication defective mutants of HSV have been proposed both as vaccine candidates and as vehicles for gene therapy because of their inability to produce infectious progeny. The immunogenicity of these HSV replication mutants, at both qualitative and quantitative levels, will directly determine their effectiveness for either of these applications. We have previously reported (Brehm et al., J. Virol., 71, 3534, 1997) that a replication defective mutant of HSV-1, which expresses a substantial level of viral genes without producing virus particles, is as efficient as wild-type HSV-1 in eliciting an HSV-specific cytotoxic T-lymphocyte (CTL) response. In this report, we have further evaluated the immunogenic potential of HSV-1-derived replication defective mutants by examining the generation of HSV-specific CTL following immunization with viruses that are severely restricted in viral gene expression due to mutations in one or more HSV alpha genes (ICP4, ICP27, ICP22, and ICP0). To measure the CTL responses induced by the HSV alpha-mutants, we have targeted two H-2Kb-restricted CTL epitopes: an epitope in a virion protein, gB (498-505), and an epitope in a nonvirion protein, ribonucleotide reductase (RR1 822-829). The HSV mutants used in this study are impaired in their ability to express gB while a majority of them still express RR1. Our findings demonstrate that a single immunization with these mutants is able to generate a strong CTL response not only to RR1 822-829, but also to gB498-505 despite their inability to express wild-type levels of gB. Furthermore, a single immunization with any individual mutant can also provide immune protection against HSV challenge. These results suggest that mutants which are restricted in gene expression may be used as effective immunogens in vivo.
由于无法产生有感染性的子代病毒，单纯疱疹病毒（HSV）的复制缺陷型突变体已被提议作为疫苗候选物和基因治疗载体。这些HSV复制突变体在定性和定量水平上的免疫原性将直接决定它们在这些应用中的有效性。我们之前曾报道过（Brehm等人，《病毒学杂志》，71卷，3534页，1997年），一种HSV-1的复制缺陷型突变体，在不产生病毒颗粒的情况下能表达大量病毒基因，在引发HSV特异性细胞毒性T淋巴细胞（CTL）反应方面与野生型HSV-1一样有效。在本报告中，我们通过检测用因一个或多个HSVα基因（ICP4、ICP27、ICP22和ICP0）突变而在病毒基因表达上受到严重限制的病毒免疫后HSV特异性CTL的产生情况，进一步评估了源自HSV-1的复制缺陷型突变体的免疫原性潜力。为了测量HSVα突变体诱导的CTL反应，我们针对了两个H-2Kb限制性CTL表位：一个在病毒体蛋白gB（498-505）中的表位，以及一个在非病毒体蛋白核糖核苷酸还原酶（RR1 822-829）中的表位。本研究中使用的HSV突变体在表达gB的能力上受损，而其中大多数仍表达RR1。我们的研究结果表明，用这些突变体进行单次免疫不仅能够对RR1 822-829产生强烈的CTL反应，而且尽管它们无法表达野生型水平的gB，但对gB498-505也能产生强烈反应。此外，用任何单个突变体进行单次免疫也能提供针对HSV攻击的免疫保护。这些结果表明，在基因表达上受到限制的突变体可在体内用作有效的免疫原。
