Testing Borrelia recurrentis isolates by using a newly developed louse-borne relapsing fever mouse model

使用新开发的虱传回归热小鼠模型测试复发疏螺旋体分离株

• 批准号: 10286259
• 负责人: Artem Rogovsky
• 金额: $ 7.58万
• 依托单位: TEXAS A&M AGRILIFE RESEARCH
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-09 至 2023-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10286259
• 关键词: Ache; African; Animal Model; Animals; Antibiotics; Antibodies; Antigenic Variation; B-Lymphocytes; Borrelia; Chromosomes; Communities; Country; Enzyme-Linked Immunosorbent Assay; Epidemic; Ethiopia; Europe; Exhibits; Feces; Fever Chills; Genes; Genetic; Genome; Hospitalization; Human; Human body; Immunocompetent; Immunocompromised Host; Immunoglobulin M; Inbred Mouse; Infection; Integration Host Factors; Left; Lice; Liquid substance; Liver; Location; Malaise; Microscopy; Modeling; Morbidity - disease rate; Mus; Nausea; Order Spirochaetales; Parasites; Pathogenesis; Patients; Pediculus humanus humanus; Plasmids; Proteins; Public Health; Reaction; Recombinants; Relapse; Relapsing Fever; Research; Research Personnel; Resources; Reverse Transcriptase Polymerase Chain Reaction; SCID Mice; Skin; Spleen; System; T-Lymphocyte; Testing; Tick-Borne Relapsing Fever; Vaccines; Virulent; Western Blotting; Work; adaptive immunity; antimicrobial; genetic makeup; human disease; human pathogen; improved; insight; mortality; mouse model; novel; pathogen; relapsing fever borrelia; research and development; response; transmission process; vaccine development; whole genome

PROJECT SUMMARY Louse-borne relapsing fever (LBRF) is a human disease caused by Borrelia recurrentis. LBRF remains a significant burden in several African nations. LBRF could account for 27% of hospital admissions. B. recurrentis is transmitted between humans by the body louse, Pediculus humanus humanus, which is a strictly human parasite. The mortality can be as high as 40%, if left untreated, and low as 1-5% when treated with antimicrobials. Treatment is often problematic because up to 76% of patients exhibit a systemic antibiotic-induced reaction, the Jarisch-Herxeimer reaction, which is associated with an elevated mortality. LBRF research has been hampered by the lack of immunocompetent animal model. Recently, we developed an immunocompetent mouse model. The mice consistently developed an increasing level of spirochetemia during day 1-3 pi and anti-Bre IgM response. However, Bre was not detected from day 4 through day 10 post infection. In contrast to Bre, tick-borne relapsing fever Borrelia (e.g., B. hermsii) have multiple peaks of spirochetemia over 7-14-day period, which is driven by antigenic variation of Vmp proteins (products of vlsp and vsp genes) allowing spirochetes to evade antibodies. The lack of secondary spirochetemia could be accounted for by genetic make-up of Bre antigenic system. Recently, genomes of A17 (year of isolation, 1985) and other Bre strains, PBeK (2004), and PAbN, PAbJ, PMaC, and PUfA (2015) were whole-genome sequenced (Marosevic et al 2017) and compared to the reference strain A1. As a result, low genetic variability (only 29-38 SNPs) was identified between the chromosome/plasmids for all of these strains. However, due to sequence similarity and variable numbers of vlp/vsl genes in lp124, there was discrepant coverage of vlp/vsl genes than surrounding regions (10-20x higher), which indicated that the numbers of vlp/vsp copies were highly variable. The latter and de novo assembly approach taken by that study precluded identification of exact numbers and location of vlp/vsp (pseudo)genes for the 6 sequenced Bre strains (Marosevic et al 2017). Thus, it is possible that the single relapse of spirochetemia observed in the EE mice (and most human patients) is due to a limited repertoire of vlp/vsl system in some Bre strains. We hypothesize that the Bre strains that possess a higher number of intact vlp/vsp copies will develop more relapses of spirochetemia. To test it, we will pursue the following Specific Aims: SA1: Determine the number of spirochetemic relapses that 7 Bre strains will develop in the novel LBRF immunocompetent mouse model. SA2: Determine the exact copy numbers of intact vlp and vsp (pseudo)genes in 7 Bre strains by using the PacBio sequencing. This is a significant and impactful proposal because novel insights into Bre pathogenesis will be provided. This study may also improve our Bre mouse model by having Bre strain(s) develop more than one spirochetemic cycle, which will allow us study the antigenic variation of Bre in greater details. Our approach is novel since, in addition to our new (the only available) immunocompetent mouse model, we will also use PacBio to accurately sequence the Bre vlp/vsp system.

项目摘要 虱子传播的复发热（LBRF）是由伯氏骨borrentis引起的人类疾病。 LBRF仍然是一个 几个非洲国家的巨大负担。 LBRF可以占住院的27％。 B. recurrentis 是由虱子人类人类人类人类人类在人类之间传播的，这是一个严格的人类 寄生虫。如果未经治疗，死亡率可能高达40％，当用抗菌药物处理时，死亡率可能高达1-5％。 治疗通常是有问题的，因为多达76％的患者表现出全身性抗生素诱导的反应，即 jarisch-------示例反应，这与死亡率升高有关。 LBRF研究受到了阻碍 由于缺乏免疫能力的动物模型。最近，我们开发了一种免疫能力的小鼠模型。 在第1-3天PI和抗BRE IgM中，小鼠始终发生螺旋藻血症的水平不断提高 回复。但是，从感染后第4天到第10天，未检测到BRE。与BRE相反，Tick-Borne 复发性发烧疏螺旋体（例如B. hermsii）在7-14天内具有多个螺旋藻血峰，即 由VMP蛋白（VLSP和VSP基因的产物）的抗原变异驱动，允许螺旋体逃避 抗体。缺乏继发性螺旋藻可以通过BRE抗原的遗传组成来解释 系统。最近，A17的基因组（孤立年份，1985年）和其他BRE菌株，PBEK（2004）和PABN， PABJ，PMAC和PUFA（2015）是全基因组测序（Marosevic等人，2017年），并将其与 参考应变A1。结果，鉴定 所有这些菌株的染色体/质粒。但是，由于序列相似性和可变数字 LP124中的VLP/VSL基因，VLP/VSL基因的范围比周围地区（高10-20x）， 这表明VLP/VSP副本的数量高度可变。后者和从头大会 该研究采用的方法排除了VLP/VSP（伪）基因的确切数字和位置的识别 对于6个测序的BRE菌株（Marosevic等，2017）。因此，可能的单一复发 在EE小鼠（和大多数人类患者）中观察到的螺旋藻血症是由于VLP/VSL系统的曲目有限 在某些bre菌株中。我们假设拥有更高数量完整的VLP/VSP的BRE菌株 副本将产生更多的螺旋藻复发。为了测试它，我们将追求以下特定目标： SA1：确定新型LBRF中7 BRE菌株将出现7 BRE菌株的螺旋体复发的数量 免疫功能小鼠模型。 SA2：确定完整VLP和VSP的确切副本编号 通过使用PACBIO测序，（伪）基因在7个BRE菌株中。这是一个重要而有影响力的建议 因为将提供对BRE发病机理的新见解。这项研究也可以改善我们的BRE鼠标 通过使BRE菌株发展多个螺旋体循环来模型，这将使​​我们研究抗原 BRE的变化更大。我们的方法是新颖的，因为除了我们的新方法（唯一可用） 免疫能力的小鼠模型，我们还将使用PACBIO准确地对BRE VLP/VSP系统进行测序。