DEN4 DELETION MUTANTS AS VACCINES & VIRUSES OF OTHER SEROTYPES AS DENGUE VACCINE

最近，已经通过反复的实验制备了活的候选登革热疫苗。 病毒在非自然宿主的培养细胞中的传代。 科学家 泰国声称，一种通过连续传代获得的DEN 2疫苗， 原代狗肾细胞对于敏感的 人类 其他血清型的活登革病毒疫苗也类似。 准备并声称是减毒的。 然而，这些观察结果 尚未得到证实，其他实验室的经验表明， 这种方法不能产生令人满意的减毒疫苗株。 因此，仍然没有安全有效的登革热疫苗， 尽管经过了50年的深入研究 我们在分子研究中积累的经验表明， 有可能产生一组登革热病毒突变体， 限制了病毒的复制此外，经验与几个 针对其他病毒的经过充分研究的活疫苗表明， 病毒复制的减少通常与病毒的减毒有关， 人类 为此目的，一系列含有一个或多个突变体的DEN 4突变体， 在5'或3'非编码（NC）区的缺失，导致减少 已经构建了猿细胞培养物中的复制能力， 分析了 缺失突变体的优势应该是 比氨基酸置换突变体更易发生表型逆转。 在这个项目中开发的一个或多个突变体可能被证明是 用于免疫人类以抵抗登革热引起的疾病 病毒 最近，我们描述了型间嵌合cDNA的构建， 替换C-PreM-E或仅替换C-PreM-E结构蛋白基因， DEN 4全长cDNA与DEN 1或DEN 2的相应基因。 表达DEN 1抗原性的活的型间登革热嵌合体 或DEN 2从用cDNA衍生的RNA转染的细胞中回收 成绩单我们发现嵌合登革病毒感染恒河猴 猴，单独给药时具有高度免疫原性， 同时作为二价疫苗。 这些嵌合体有效地 诱导针对登革热病毒攻击的保护性免疫， 相同的血清型 最近，一个可行的DEN 3/DEN 4嵌合体也被发现。 使用DEN 4 cDNA构建。 这些令人鼓舞的观察结果表明， 含有DEN 4和DEN 1/DEN 4的活多价登革热疫苗， DEN 2/DEN 4和DEN 3/DEN 4嵌合体可能是可行的。 使用所有四个 在相同DEN 4背景下的登革热病毒血清型代表了一种新的 登革热疫苗战略。

Recently, live candidate dengue vaccines have been prepared by repeated passage of virus in cultured cells of an unnatural host. Scientists in Thailand claimed that a DEN2 vaccine derived by serial passages in primary dog kidney cells was satisfactorily attenuated for susceptible humans. Live dengue virus vaccines of other serotypes were similarly prepared and claimed to be attenuated. However, these observations have not been confirmed and experience from other laboratories indicated that this approach did not yield satisfactorily attenuated vaccine strains. Thus, a safe and effective dengue vaccine is still not available, despite five decades of intensive research. The cumulative experience gained during our molecular studies has shown that it is possible to produce a panel of dengue virus mutants that are restricted in viral replication. Also, experience with several well-studied live vaccines directed against other viruses indicates that reduced viral replication is usually associated with attenuation for humans. For this purpose, a series of DEN4 mutants containing a deletion in the 5' or 3' noncoding (NC) region that results in reduced replicative capacity in simian cell culture have been constructed and analyzed. Deletion mutants should have the advantage of being less subject to reversion of phenotype than amino acid substitution mutants. One or more mutants developed during this project might prove to be useful for immunization of humans against disease caused by dengue virus. Recently, we described construction of intertypic chimeric cDNA by replacing the C-PreM-E or only the PreM-E structural protein genes of full-length DEN4 cDNA with the corresponding genes of DEN1 or DEN2. Viable intertypic dengue chimeras that express the antigenicity of DEN1 or DEN2 were recovered from cells transfected with the cDNA-derived RNA transcripts. We showed that chimeric dengue viruses infected rhesus monkeys and were highly immunogenic when given individually or simultaneously as a bivalent vaccine. These chimeras were effective in inducing protective immunity against challenge with dengue virus of the same serotype. More recently, a viable DEN3/DEN4 chimera was also constructed using DEN4 cDNA. These encouraging observations suggest that a live multivalent dengue vaccine containing DEN4 and DEN1/DEN4, DEN2/DEN4 and DEN3/DEN4 chimeras might be feasible. The use of all four dengue virus serotypes on the same DEN4 background represents a novel dengue vaccine strategy.