PDF(Pubmed)
Abstract：
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly evolved to generate several antigenic variants. These variants have raised concerns whether pre-existing immunity to vaccination or prior infection would be able to protect against the newly emerging SARS-CoV-2 variants or not. We isolated SARS-CoV-2 from the coronavirus disease 2019 (COVID-19)-confirmed patients in the beginning of the first (April/May 2020) and second (April/May 2021) waves of COVID-19 in India (Hisar, Haryana). Upon complete nucleotide sequencing, the viruses were found to be genetically related with wild-type (WT) and Delta variants of SARS-CoV-2, respectively. The Delta variant of SARS-CoV-2 produced a rapid cytopathic effect (24-36 h as compared to 48-72 h in WT) and had bigger plaque size but a shorter life cycle (~6 h as compared to the ~8 h in WT). Furthermore, the Delta variant achieved peak viral titers within 24 h as compared to the 48 h in WT. These evidence suggested that the Delta variant replicates significantly faster than the WT SARS-CoV-2. The virus neutralization experiments indicated that antibodies elicited by vaccination are more efficacious in neutralizing the WT virus but significantly less potent against the Delta variant. Our findings have implications in devising suitable vaccination, diagnostic and therapeutic strategies, besides providing insights into understanding virus replication and transmission.
摘要：
严重急性呼吸道综合征冠状病毒2（SARS-CoV-2）已迅速进化以产生几种抗原变体。这些变体引起了人们的担忧，即对疫苗接种或先前感染的预先存在的免疫力是否能够防止新出现的SARS-CoV-2变体。我们在印度首次(2020年4月/5月)和第二次(2021年4月/5月)COVID-19波初(Hisar，哈里亚纳邦）。在完成核苷酸测序后，发现这些病毒分别与SARS-CoV-2的野生型（WT）和Delta变体遗传相关。SARS-CoV-2的Delta变体产生了快速的细胞病变效应（24-36小时，而WT为48-72小时），并且斑块大小更大，但生命周期更短（约6小时，而WT为8小时）。此外，与WT中的48小时相比，Delta变体在24小时内达到了病毒滴度的峰值。这些证据表明，Delta变体的复制速度明显快于WTSARS-CoV-2。病毒中和实验表明,通过疫苗接种引发的抗体在中和WT病毒方面更有效,但针对Delta变体的效力显著较低。我们的发现对设计合适的疫苗接种有影响，诊断和治疗策略，除了提供了解病毒复制和传播的见解。
