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Longevity of antibody and T-cell responses against outer membrane antigens of Orientia tsutsugamushi in scrub typhus patients
- Source :
- Emerging Microbes & Infections
- Publication Year :
- 2017
-
Abstract
- Scrub typhus, caused by Orientia tsutsugamushi infection, has been a serious public health issue in the Asia-Pacific region, with rising incidence and sporadic outbreaks. However, human protective immunity against specific antigens has been poorly characterized for this bacterium. In addition, immunity produced in early vaccine trials or even after natural infections, did not last long and had poor cross-reactivity among various genotypes. Here, we systematically investigated the kinetics and magnitude of specific adaptive immunity against two membrane antigens, 56 kDa type-specific antigen (TSA56) and surface cell antigen A (ScaA), that are involved in bacterial adhesion and invasion of the host in 64 recovered scrub typhus patients. Antibody responses to the bacterial antigens in patients were generally short-lived and waned to baseline levels 2 years after recovery. The anti-TSA56 IgG responses were predominantly composed of the IgG1 and IgG3 subclasses and persisted for up to 1 year after recovery, whereas IgG specific to ScaA primarily consisted of more transient IgG1, with limited responses by other subclasses. Cellular immunity, including CD4 and CD8 T-cells specific to membrane antigens, also rapidly declined from 1 year after infection, as measured by enzyme-linked immunospot (ELISPOT) assays and flow cytometry. The short longevity of antigen-specific adaptive immunity might be attributable to limited memory responses, as observed in earlier vaccine studies using whole bacterial antigens. Finally, we identified HLA-A*0201-restricted and highly conserved CD8 T-cell epitopes in the TSA56 antigen, which may be valuable tools for assessing cellular immunity against O. tsutsugamushi and developing an effective scrub typhus vaccine.
- Subjects :
- 0301 basic medicine
Cellular immunity
Orientia tsutsugamushi
Epidemiology
T-Lymphocytes
030231 tropical medicine
Immunology
Scrub typhus
Biology
Adaptive Immunity
Microbiology
03 medical and health sciences
0302 clinical medicine
Antigen
Immunity
Virology
antibody
vaccine
Drug Discovery
HLA-A2 Antigen
medicine
Humans
Aged
Antigens, Bacterial
Immunity, Cellular
scrub typhus
ELISPOT
T cell
General Medicine
Middle Aged
medicine.disease
Acquired immune system
biology.organism_classification
bacterial infections and mycoses
Antibodies, Bacterial
030104 developmental biology
Infectious Diseases
B7-1 Antigen
Parasitology
Female
Original Article
Bacterial antigen
Bacterial Outer Membrane Proteins
Subjects
Details
- ISSN :
- 22221751
- Volume :
- 6
- Issue :
- 12
- Database :
- OpenAIRE
- Journal :
- Emerging microbesinfections
- Accession number :
- edsair.doi.dedup.....85072089db6f572f1f8315541df67b4c