Development of a Highly Sensitive and Specific Acute Diagnostic Test for Tick-Borne Rickettsioses
Abstract
Tick-borne rickettsioses are a group of disease that caused by several species of rickettsiae and transmitted to humans by ticks. Tick-borne rickettsioses continue to pose a significant threat to public health and to military Service members. Tick-borne diseases among training or deployed troops are not just theoretical risks but have actually occurred, with very high infection rates in endemic areas such as South Korea and Northern Sri Lanka. Tick-borne rickettsioses are transmitted to humans by ticks and can be life-threatening, or cause serious sequelae, if not diagnosed and treated in a timely manner. However, tick-borne rickettsioses, such as Rocky Mountain spotted fever, are difficult to diagnose early enough for effective treatment, mainly due to the nonspecific signs and symptoms of illness and lack of early-stage diagnostic tests. This proposed project will address the specific Focus Area: “accurate diagnostics and biomarkers for tick-borne rickettsial diseases.” This research is proposed for the near-term (2 years) development of a convenient point of care, acute-phase diagnostic test for multiple tick-borne rickettsioses. We recently discovered a novel pathogen protein, RC0497, by quantitative proteomic studies. We have demonstrated the circulation of RC0497 in both experimental model of infection and patients with tick-borne rickettsioses during the acute stage of disease. While we could in principle use the quantitative proteomic analysis as a diagnostic test, it requires sophisticated equipment and is too complex for clinical application, especially in rural or military settings. Thus, we propose to develop a lateral-flow assay (the format of the home pregnancy test) to quantitatively detect RC0497 as a timely diagnostic test for tick-borne rickettsioses. If successful, this assay will enable early, effective treatment of patients with tick-borne rickettsioses, which will significantly reduce the public health burden of disease. We will begin with aiming to characterize how early and at what levels this protein biomarker appears in the serum of experimental models of tick-borne rickettsioses. A parallel effort will be the development of a highly sensitive lateral flow assay for quantitative detection of RC0497 as an acute-phase diagnostic for tick-borne rickettsioses. In the second aim, in order to increase the sensitivity and applicability of the test, we will use the same phosphor materials found in “glow-in-the-dark” toys and safety materials, ground into nanoscale particles, which are used as reporters in the lateral flow assay. A smartphone flash and camera, driven by a custom app we have written, excites the phosphors to extreme brightness and images them before they can fade, giving extremely good sensitivity of detection. The third aim is to evaluate how reliable and accurate this diagnostic test will be by using acute-phase serum from patients with tick-borne rickettsioses. Serum samples from healthy individuals will be used as negative controls throughout the experiments. Recombinant RC0497 will be used as a control as well as a reference for optimizing the lateral flow assay. This study is both conceptually and technically innovative because this will be the first laboratory test for early diagnosis of tick-borne rickettsioses by a point-of-care test using the novel “glow-in-dark” nanophosphor materials. Several pathogenic rickettsial species have this protein, RC0497, with the highly conserved sequence, and so this assay is proposed to be useful for timely diagnosis of several tick-borne rickettsioses. The successful completion of the project will have a great impact on how the patients with tick-borne rickettsioses are managed by healthcare providers, leading to timely treatment and better outcomes. This assay will also distinguish active infection from previous exposures to rickettsial pathogens and will allow acquisition of accurate data on surveillance and epidemiology of tick-borne rickettsio
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 10, 2021
- Source ID
- W81XWH2010834
Entities
People
- Rong Fang
Organizations
- United States Army
- University of Texas Medical Branch