PDF(Pubmed)
Abstract：
The S2 subunit of infectious bronchitis virus (IBV) is a heavily glycosylated protein that can impact various characteristics of the virus. It is currently known that N-glycosylation modifications are predominantly located on the S2 subunit. However, the exact role of their N-glycosylation modification remains undisclosed. To elucidate the function of these N-glycosylation sites, we identified 14 common sites distributed on the S2 subunit of the 5 genotypes of IBV in present study. Subsequently, we selected 7 sites to generate mutants and assessed their impact on viral virulence, replication ability, and antigenicity. Our finding revealed that only 2 substitutions, N545S and K717N, increased the viral replication titer and antigenicity, and ultimately the pathogenicity in chicks. To delve into the mechanisms underlying this increased pathogenicity, we discovered that K717N can change the structure of antigenic epitopes. The N545S substitution not only influenced antigenic epitope structure, but also enhanced the ability of the virus to enter CEKs during the early stages of viral replication. These results suggest that the enhanced viral pathogenicity associated with N545S and K717N substitutions is multifaceted, with acceleration of the viral membrane fusion process and alterations in epitope structure representing crucial factors in the capability of N-glycosylation modifications to boost viral virulence. These insights provide valuable guidance for the efficient development of live attenuated vaccines.
摘要：
传染性支气管炎病毒（IBV）的S2亚基是一种高度糖基化的蛋白质，可以影响病毒的各种特征。目前已知N-糖基化修饰主要位于S2亚基上。然而,其N-糖基化修饰的确切作用仍未公开。为了阐明这些N-糖基化位点的功能，在本研究中，我们确定了分布在IBV5个基因型的S2亚基上的14个常见位点。随后，我们选择了7个位点来产生突变体，并评估它们对病毒毒力的影响，复制能力，和抗原性。我们的发现显示只有2个替换，N545S和K717N,增加病毒复制滴度和抗原性，最终是雏鸡的致病性。为了深入研究这种致病性增加的潜在机制，我们发现K717N可以改变抗原表位的结构。N545S取代不仅影响抗原表位结构，而且还增强了病毒在病毒复制的早期阶段进入CEK的能力。这些结果表明，与N545S和K717N取代相关的病毒致病性增强是多方面的，随着病毒膜融合过程的加速和表位结构的改变，代表了N-糖基化修饰增强病毒毒力的能力的关键因素。这些见解为高效开发减毒活疫苗提供了有价值的指导。
