Department of Virology, Dhaka Medical College Hospital, Dhaka 1000, Bangladesh.
GenExpress Gesellschaft für Proteindesign GmbH, Eresburgstraße 22-23 D, 12103 Berlin, Germany.
Viruses. 2021 Nov 19;13(11):2310. doi: 10.3390/v13112310.
Novel SARS-CoV-2 variants are emerging at an alarming rate. The delta variant and other variants of concern (VoC) carry spike (S)-protein mutations, which have the potential to evade protective immunity, to trigger break-through infections after COVID-19 vaccination, and to propagate future waves of COVID-19 pandemic. To identify SARS CoV-2 variants in Bangladesh, patients who are RT-PCR-positive for COVID-19 infections in Dhaka were screened by a RT-PCR melting curve analysis for spike protein mutations. To assess the anti-SARS CoV-2 antibody responses, the levels of the anti-S -proteins IgA and IgG and the anti-N-protein IgG were measured by ELISA. Of a total of 36 RT-PCR positive samples (75%), 27 were identified as delta variants, with one carrying an additional Q677H mutation and two with single nucleotide substitutions at position 23029 (compared to Wuhan-Hu-1 reference NC 045512) in the genome sequence. Three (8.3%) were identified as beta variants, two (5.5%) were identified as alpha variants, three (8.3%) were identified as having a B.1.1.318 lineage, and one sample was identified as an eta variant (B.1.525) carrying an additional V687L mutation. The trend of higher viral load (lower Cp values) among delta variants than in the alpha and beta variants was of borderline statistical significance ( = 0.045). Prospective studies with larger Bangladeshi cohorts are warranted to confirm the emergence of S-protein mutations and their association with antibody response in natural infection and potential breakthrough in vaccinated subjects.
新的 SARS-CoV-2 变体正在以惊人的速度出现。德尔塔变体和其他关切变体 (VoC) 携带刺突 (S)-蛋白突变，有可能逃避保护性免疫，在 COVID-19 疫苗接种后引发突破性感染，并引发未来的 COVID-19 大流行浪潮。为了在孟加拉国识别 SARS-CoV-2 变体，对达卡 COVID-19 感染 RT-PCR 阳性的患者进行 RT-PCR 熔解曲线分析，以筛选刺突蛋白突变。为了评估抗 SARS-CoV-2 抗体反应，通过 ELISA 测量抗 S-蛋白 IgA 和 IgG 以及抗 N-蛋白 IgG 的水平。在总共 36 个 RT-PCR 阳性样本（75%）中，有 27 个被鉴定为德尔塔变体，其中一个携带额外的 Q677H 突变，两个在基因组序列中 23029 位（与武汉-Hu-1 参考 NC_045512 相比）有单核苷酸取代。三个（8.3%）被鉴定为 beta 变体，两个（5.5%）被鉴定为 alpha 变体，三个（8.3%）被鉴定为具有 B.1.1.318 谱系，一个样本被鉴定为 eta 变体（B.1.525）携带额外的 V687L 突变。德尔塔变体的病毒载量较高（较低的 Cp 值）的趋势与 alpha 和 beta 变体相比具有边缘统计学意义（=0.045）。需要进行具有更大孟加拉国队列的前瞻性研究，以确认 S-蛋白突变的出现及其与自然感染和接种疫苗者潜在突破的抗体反应的关联。
