Blazevic Azra, Xia Mei, Turan Aldin, Tennant Janice, Hoft Daniel F
Department of Internal Medicine, Saint Louis University, Doisy Research Center, 8th floor, 1100 S. Grand Blvd., St. Louis, MO 63104, United States.
Department of Internal Medicine, Saint Louis University, Doisy Research Center, 8th floor, 1100 S. Grand Blvd., St. Louis, MO 63104, United States.
Tuberculosis (Edinb). 2017 Jul;105:108-112. doi: 10.1016/j.tube.2017.05.001. Epub 2017 May 4.
Despite the great effort to develop an effective vaccine against tuberculosis (TB) there is currently no reliable and safe human challenge model that can be used for in vivo evaluation of new TB vaccine candidates and/or elucidation of the mechanisms of TB protective immunity. In this study, five volunteers were challenged with BCG intradermally (ID). Swab specimens were collected at multiple time points from the vaccination site pre- and post-vaccination to quantitate mycobacterial shedding as a surrogate of in vivo mycobacterial immunity. We compared the performance of the TaqMan qPCR assay against colony-forming unit cultures on 7H10 agar plates, and time to positivity (TTP) of mycobacterial growth indicator tubes (MGIT) in order to evaluate the reproducibility and sensitivity in measuring BCG burden in swab specimens. BCG was detected in swab specimens from all five volunteers by at least one method, and no single method was superior in terms of sensitivity and reproducibility. A comparison of all three methods showed significant correlations by Spearman's rank test between 7H10 agar plating and qPCR (R = 0.601, P = 0.00072), MGIT culture TTP and 7H10 agar plating (R = 0.412, P = 0.029) as well as MGIT culture TTP and qPCR (R = -0.708, P = 0.00003). However, the three methods were somewhat different with regard to early versus late detection of BCG shedding post-challenge. This ID BCG challenge model has unique potential to further explore correlations between reactogenicity and immune mechanisms involved in protection against mycobacterial infections, and could therefore become a reliable tool in the evaluation process of new TB vaccination strategies.
尽管人们付出了巨大努力来研发一种有效的抗结核疫苗，但目前尚无可靠且安全的人体激发模型可用于体内评估新型结核疫苗候选物和/或阐明结核保护性免疫机制。在本研究中，五名志愿者接受了皮内注射卡介苗（BCG）的激发。在接种前后的多个时间点从接种部位采集拭子标本，以定量分枝杆菌脱落情况，作为体内分枝杆菌免疫的替代指标。我们比较了TaqMan qPCR检测法与7H10琼脂平板上的菌落形成单位培养法以及分枝杆菌生长指示管（MGIT）的阳性时间（TTP），以评估测量拭子标本中卡介苗载量的重现性和敏感性。通过至少一种方法在所有五名志愿者的拭子标本中检测到了卡介苗，就敏感性和重现性而言，没有单一方法具有优势。对所有三种方法的比较表明，通过Spearman秩检验，7H10琼脂平板培养法与qPCR之间存在显著相关性（R = 0.601，P = 0.00072），MGIT培养TTP与7H10琼脂平板培养法之间存在显著相关性（R = 0.412，P = 0.029），以及MGIT培养TTP与qPCR之间存在显著相关性（R = -0.708，P = 0.00003）。然而，这三种方法在激发后卡介苗脱落的早期与晚期检测方面存在一定差异。这种皮内注射卡介苗激发模型具有独特的潜力，可进一步探索反应原性与抗分枝杆菌感染保护中涉及的免疫机制之间的相关性，因此可能成为新的结核疫苗接种策略评估过程中的可靠工具。
