Department of Medical Microbiology and Infectious Diseases, Canisius Wilhelmina Hospital (CWZ), Nijmegen, Netherlands.
Centre of Expertise in Mycology, Radboudumc/CWZ, Nijmegen, Netherlands.
Front Cell Infect Microbiol. 2019 Mar 29;9:82. doi: 10.3389/fcimb.2019.00082. eCollection 2019.
More than a decade ago a short tandem repeat-based typing method was developed for the fungus . This STR assay is based on the analysis of nine short tandem repeat markers. Interpretation of this STR assay is complicated when there are only one or two differences in tandem repeat markers between isolates, as the stability of these markers is unknown. To determine the stability of these nine markers, a STR assay was performed on 73-100 successive generations of five clonally expanded isolates. In a total of 473 generations we found five times an increase of one tandem repeat unit. Three changes were found in the trinucleotide repeat marker STR 3A, while the other two were found in the trinucleotide repeat marker STR 3C. The di- or tetranucleotide repeats were not altered. The altered STR markers 3A and 3C demonstrated the highest number of repeat units (≥50) as compared to the other markers (≤26). Altogether, we demonstrated that 7 of 9 STR markers remain stable for 473 generations and that the frequency of alterations in tandem repeats is positively correlated with the number of repeats. The potential low level instability of STR markers 3A and 3C should be taken into account when interpreting STR data during an outbreak.
十多年前，人们开发了一种基于短串联重复序列的真菌分型方法。该 STR 分析基于对 9 个短串联重复标记的分析。当分离株之间只有一个或两个串联重复标记存在差异时，这种 STR 分析的解释就变得复杂了，因为这些标记的稳定性是未知的。为了确定这 9 个标记的稳定性，对 5 株克隆扩增的分离株进行了 73-100 代的 STR 分析。在总共 473 代中，我们发现有一次串联重复单元增加了一个。在三核苷酸重复标记 STR3A 中发现了 3 次变化，而在另两个三核苷酸重复标记 STR3C 中发现了 2 次变化。二核苷酸或四核苷酸重复未发生改变。与其他标记（≤26）相比，改变的 STR 标记 3A 和 3C 显示出最高的重复单元数（≥50）。总之，我们证明了在 473 代中，9 个 STR 标记中有 7 个保持稳定，串联重复的改变频率与重复次数呈正相关。在疫情爆发期间解释 STR 数据时，应考虑 STR 标记 3A 和 3C 的潜在低水平不稳定性。
