Re-evaluating the sensitivity of the rabbit infectivity test for Treponema pallidum in modern era

Tong, Man‐Li; Zhang, Huilin; Zhu, Xiao-Zhen; Fan, Jin-Yi; Gao, Kun; Lin, Li‐Rong; Liu, Lili; Li, Shulian; Lin, Hui-Ling; Lin, Zhifeng; Niu, Jianjun; Zheng, Weihong

doi:10.1016/j.cca.2016.11.031

Cited by 29 publications

(24 citation statements)

References 27 publications

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“…Indeed, the rabbit that was injected with CDC-SF007, which successfully grew in vivo, did not show any discernible orchitis even when seroreactive and PCR+, while the rabbit with CDC-SF003 developed orchitis beginning in week 6 when an increase in antibody titers was first noted. Consistent with previous studies [9,26,61,64,65], these observations indicate that including additional detection methods for treponemal propagation in rabbits can avoid overlooking an active infection that could inadvertently be cleared by the immune response before treponemal harvest can be performed. Of note, when comparing serology and PCR, both methods generally showed a reactive or positive result at comparable time points post infection for a given rabbit, which aligns with a previous study [61].…”

Section: Discussionsupporting

confidence: 89%

Successful isolation of Treponema pallidum strains from patients’ cryopreserved ulcer exudate using the rabbit model

et al. 2020

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Clinical isolates of Treponema pallidum subspecies pallidum (T. pallidum) would facilitate study of prevalent strains. We describe the first successful rabbit propagation of T. pallidum from cryopreserved ulcer specimens. Fresh ulcer exudates were collected and cryopreserved with consent from syphilis-diagnosed patients (N = 8). Each of eight age-matched adult male rabbits were later inoculated with a thawed specimen, with two rabbits receiving 1.3 ml intratesticularly (IT), and six receiving 0.6 ml intravenously (IV) and IT. Monitoring of serology, blood PCR and orchitis showed that T. pallidum grew in 2/8 rabbits that were inoculated IV and IT with either a penile primary lesion specimen (CDC-SF003) or a perianal secondary lesion specimen (CDC-SF007). Rabbit CDC-SF003 was seroreactive by T. pallidum Particle Agglutination (TP-PA) and Rapid Plasma Reagin (RPR) testing, PCR+, and showed orchitis by week 6. Euthanasia was performed in week 7, with treponemal growth in the testes confirmed and quantified by qPCR and darkfield microscopy (DF). Serial passage of the extract in a second age-matched rabbit also yielded treponemes. Similarly, rabbit CDC-SF007 showed negligible orchitis, but was seroreactive and PCR+ by week 4 and euthanized in week 6 to yield T. pallidum, which was further propagated by second passage. Using the 4-component molecular typing system for syphilis, 3 propagated strains (CDC-SF003, CDC-SF007, CDC-SF008) were typed as 14d9f, 14d9g, and 14d10c, respectively. All 3 isolates including strain CDC-SF011, which was not successfully propagated, had the A2058G mutation associated with azithromycin resistance. Our results show that immediate cryopreservation of syphilitic ulcer exudate can maintain T. pallidum viability for rabbit propagation.

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Section: Discussionsupporting

confidence: 89%

Successful isolation of Treponema pallidum strains from patients’ cryopreserved ulcer exudate using the rabbit model

et al. 2020

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“…The T. pallidum Nichols strain was kindly provided by Lorenzo Giacani, Ph.D. (University of Washington, Seattle) and was propagated via intra-testicular serial passage in New Zealand white rabbits to maintain virulence in our laboratory as previously described [ 12 ]. Forty-five male New Zealand white rabbits (purchased from the Xiamen University Laboratory Animal Center, weighing approximately three kilograms each) with negative results in both the reactive rapid plasma reagin and T. pallidum particle agglutination tests, were randomly assigned to two groups, a blank group ( n = 15) and an infection group ( n = 30).…”

Section: Methodsmentioning

confidence: 99%

Development of tissue inflammation accompanied by NLRP3 inflammasome activation in rabbits infected with Treponema pallidum strain Nichols

et al. 2018

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BackgroundThe inflammasome responses in Treponema pallidum infection have been poorly understood to date. This study aimed to investigate the expression of the nucleotide-binding leucine-rich receptor protein 3 (NLRP3) inflammasome in the development of tissue inflammation in rabbits infected with T. pallidum.MethodsForty-five rabbits were randomly assigned to a blank group or an infection group, and the latter was divided into no benzathine penicillin G (BPG) and BPG treatment subgroups. Rabbits in the infection group were injected intradermally with 0.1 mL of a 107/mL T. pallidum suspension at 10 marked sites along the back, and the blank group was treated with normal saline. The BPG treatment subgroup received 200,000 U of BPG administered intramuscularly twice, at 14 d and 21 d post-infection. The development of lesions was observed, and biopsies of the injection site and various organs, including the kidney, liver, spleen, lung, and testis, were obtained for NLRP3, caspase-1, and interleukin-1β (IL-1β) mRNA analysis during infection. Blood was also collected for the determination of IL-1β concentration.ResultsRabbits infected with T. pallidum (both the BPG treatment and no BPG treatment subgroups), exhibited NLRP3 inflammasome activation and IL-1β secretion in cutaneous lesions, showing a trend in elevation to decline; NLRP3 mRNA expression reached a peak at 18 d in the BPG treatment subgroup and 21 d in the no BPG treatment subgroup and returned to “normal” levels [vs. the blank group (P > 0.05)] at 42 d post-infection. The trend was similar to the change in cutaneous lesions in the infected rabbits, which reached a peak at 16 d in the BPG treatment subgroup and 18 d in the no BPG treatment subgroup. NLRP3, caspase-1, and IL-1β mRNA expression levels were slightly different in different organs. NLRP3 inflammasome activation was also observed in the kidney, liver, lung, spleen and testis. IL-1β expression was observed in the kidney, liver, lung and spleen; however, there was no detectable level of IL-1β in the testes of the infected rabbits.ConclusionsThis study established a clear link between NLRP3 inflammasome activation and the development of tissue inflammation in rabbits infected with T. pallidum. BPG therapy imperceptibly adjusted syphilitic inflammation.

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“…This information can provide a fresh perspective to help researchers address the current challenges. the sensitivity of rabbit infectivity test in current post-antibiotic era is no longer highly sensitive, 8 and high false-positive or falsenegative result of microscopy test usually occurs when laboratory workers lack experiences to distinguish T. pallidum from commensal treponemas. All these factors make pathogenic detection arduous in extensive clinical application.…”

Section: Conventional Detection Of Syphilismentioning

confidence: 99%

“…They have been recognized as the gold standard in syphilis diagnosis. However, T. pallidum still encounter difficulties in extra‐corporal cultivation even though a new article expounded T. pallidum can be co‐incubated in rabbit epithelial cell for 180 days; the sensitivity of rabbit infectivity test in current post‐antibiotic era is no longer highly sensitive, and high false‐positive or false‐negative result of microscopy test usually occurs when laboratory workers lack experiences to distinguish T. pallidum from commensal treponemas . All these factors make pathogenic detection arduous in extensive clinical application.…”

Section: Introductionmentioning

confidence: 99%

PCR detection for syphilis diagnosis: Status and prospects

Zhou

Zhang

et al. 2019

Clinical Laboratory Analysis

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Syphilis, a re‐emerging public health problem worldwide caused by Treponema pallidum subsp pallidum (T. pallidum), usually induces systemic and chronic inflammation in hosts who do not receive timely therapy after exposing to high‐risk factors such as leprous sexual contact. Before the treatment, rapid and accurate detection of syphilis is essential. However, the existing detection methods, which focus on the treponemal or non‐treponemal antibody test, both have inherent limitations. For instance, both of them cannot distinguish the stage and severity of syphilis. Non‐treponemal test such as RPR, which is generally deemed to be used for assessing treatment response, is influenced by biological false positives. Therefore, it is imperative to seek out a new and effective diagnostic test. With recent advancements in molecular biology and whole‐genome sequencing, the molecular diagnosis has increased in popularity, especially the use of polymerase chain reaction (PCR). Here, we firstly present a mini‐review on the research of PCR detection methods used for syphilis diagnosis over the past decade, and we then compare these methodologies to assess their potential and the challenges faced. This information can provide a fresh perspective to help researchers address the current challenges.

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Re-evaluating the sensitivity of the rabbit infectivity test for Treponema pallidum in modern era

Cited by 29 publications

References 27 publications

Successful isolation of Treponema pallidum strains from patients’ cryopreserved ulcer exudate using the rabbit model

Successful isolation of Treponema pallidum strains from patients’ cryopreserved ulcer exudate using the rabbit model

Development of tissue inflammation accompanied by NLRP3 inflammasome activation in rabbits infected with Treponema pallidum strain Nichols

PCR detection for syphilis diagnosis: Status and prospects

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