Modified Vaccinia Virus Ankara Exerts Potent Immune Modulatory Activities in a Murine Model

BackgroundModified vaccinia virus Ankara (MVA), a highly attenuated strain of vaccinia virus, has been used as vaccine delivery vector in preclinical and clinical studies against infectious diseases and malignancies. Here, we investigated whether an MVA which does not encode any antigen (Ag) could be exploited as adjuvant per se.
Methodology/Principal FindingsWe showed that dendritic cells infected in vitro with non-recombinant (nr) MVA expressed maturation and activation markers and were able to efficiently present exogenously pulsed Ag to T cells. In contrast to the dominant T helper (Th) 1 biased responses elicited against Ags produced by recombinant MVA vectors, the use of nrMVA as adjuvant for the co-administered soluble Ags resulted in a long lasting mixed Th1/Th2 responses.
Conclusions/SignificanceThese findings open new ways to potentiate and modulate the immune responses to vaccine Ags depending on whether they are co-administered with MVA or encoded by recombinant viruses.

背景 修饰型安卡拉痘苗病毒（Modified vaccinia virus Ankara, MVA）是一种高度减毒的痘苗病毒毒株，已作为疫苗递送载体被应用于针对传染病与恶性肿瘤的临床前及临床研究中。本研究旨在探讨不编码任何抗原（antigen, Ag）的MVA是否可直接用作佐剂。
方法与主要结果 本研究证实，经体外感染非重组（non-recombinant, nr）MVA的树突状细胞（dendritic cells）可表达成熟与活化标志物，并能够高效地将外源致敏抗原呈递给T细胞。与重组MVA载体所表达抗原诱导的主导性T辅助细胞（T helper, Th）1型偏倚免疫应答不同，将nrMVA作为共递送可溶性抗原的佐剂使用时，可诱导产生持久的混合Th1/Th2型免疫应答。
结论与意义 本研究结果为依据疫苗抗原是与MVA共递送还是由重组病毒编码，来增强并调控针对疫苗抗原的免疫应答提供了全新的思路。