Department of Biology, Trent University, Peterborough, ON, Canada.
Virol J. 2010 Feb 18;7:41. doi: 10.1186/1743-422X-7-41.
Viruses included in the family Iridoviridae are large, icosahedral, dsDNA viruses that are subdivided into 5 genera. Frog virus 3 (FV3) is the type species of the genus Ranavirus and the best studied iridovirus at the molecular level. Typically, antibodies directed against a virus act to neutralize the virus and limit infection. Antibody dependent enhancement occurs when viral antibodies enhance infectivity of the virus rather than neutralize it.
Here we show that anti-FV3 serum present at the time of FV3 infection enhances infectivity of the virus in two non-immune teleost cell lines. We found that antibody dependent enhancement of FV3 was dependent on the Fc portion of anti-FV3 antibodies but not related to complement. Furthermore, the presence of anti-FV3 serum during an FV3 infection in a non-immune mammalian cell line resulted in neutralization of the virus. Our results suggest that a cell surface receptor specific to teleost cell lines is responsible for the enhancement.
This report represents the first evidence of antibody dependent enhancement in iridoviruses. The data suggests that anti-FV3 serum can either neutralize or enhance viral infection and that enhancement is related to a novel antibody dependent enhancement pathway found in teleosts that is Fc dependent.
虹彩病毒科的病毒是大型二十面体双链 DNA 病毒，分为 5 个属。蛙病毒 3（FV3）是 Ranavirus 属的模式种，也是在分子水平上研究最多的虹彩病毒。通常情况下，针对病毒的抗体可起到中和病毒并限制感染的作用。而抗体依赖性增强（ADE）则是指病毒抗体增强了病毒的感染力，而非中和它。
本研究表明，在 FV3 感染时存在的抗 FV3 血清可增强两种非免疫硬骨鱼类细胞系中病毒的感染力。我们发现，FV3 的 ADE 依赖于抗 FV3 抗体的 Fc 部分，而与补体无关。此外，在非免疫哺乳动物细胞系中 FV3 感染期间存在抗 FV3 血清会导致病毒被中和。我们的结果表明，特定于硬骨鱼类细胞系的细胞表面受体负责增强作用。
本报告首次证明了虹彩病毒中的抗体依赖性增强。数据表明，抗 FV3 血清既能中和也能增强病毒感染，增强作用与在硬骨鱼类中发现的新型、依赖于 Fc 的抗体依赖性增强途径有关。
