Strong interferon-gamma mediated cellular immunity to scrub typhus demonstrated using a novel whole cell antigen ELISpot assay in rhesus macaques and humans.

Scrub typhus is a febrile infection caused by the obligate intracellular bacterium Orientia tsutsugamushi, which causes significant morbidity and mortality across the Asia-Pacific region. The control of this vector-borne disease is challenging due to humans being dead-end hosts, vertical maintenance...

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Main Authors: Manutsanun Sumonwiriya, Daniel H Paris, Piyanate Sunyakumthorn, Tippawan Anantatat, Kemajittra Jenjaroen, Suchintana Chumseng, Rawiwan Im-Erbsin, Ampai Tanganuchitcharnchai, Suthatip Jintaworn, Stuart D Blacksell, Fazle R Chowdhury, Barbara Kronsteiner, Prapit Teparrukkul, Robin L Burke, Eric D Lombardini, Allen L Richards, Carl J Mason, James W Jones, Nicholas P J Day, Susanna J Dunachie
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2017-09-01
Series:PLoS Neglected Tropical Diseases
Online Access:https://journals.plos.org/plosntds/article/file?id=10.1371/journal.pntd.0005846&type=printable
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author Manutsanun Sumonwiriya
Daniel H Paris
Piyanate Sunyakumthorn
Tippawan Anantatat
Kemajittra Jenjaroen
Suchintana Chumseng
Rawiwan Im-Erbsin
Ampai Tanganuchitcharnchai
Suthatip Jintaworn
Stuart D Blacksell
Fazle R Chowdhury
Barbara Kronsteiner
Prapit Teparrukkul
Robin L Burke
Eric D Lombardini
Allen L Richards
Carl J Mason
James W Jones
Nicholas P J Day
Susanna J Dunachie
author_facet Manutsanun Sumonwiriya
Daniel H Paris
Piyanate Sunyakumthorn
Tippawan Anantatat
Kemajittra Jenjaroen
Suchintana Chumseng
Rawiwan Im-Erbsin
Ampai Tanganuchitcharnchai
Suthatip Jintaworn
Stuart D Blacksell
Fazle R Chowdhury
Barbara Kronsteiner
Prapit Teparrukkul
Robin L Burke
Eric D Lombardini
Allen L Richards
Carl J Mason
James W Jones
Nicholas P J Day
Susanna J Dunachie
author_sort Manutsanun Sumonwiriya
collection DOAJ
description Scrub typhus is a febrile infection caused by the obligate intracellular bacterium Orientia tsutsugamushi, which causes significant morbidity and mortality across the Asia-Pacific region. The control of this vector-borne disease is challenging due to humans being dead-end hosts, vertical maintenance of the pathogen in the vector itself, and a potentially large rodent reservoir of unclear significance, coupled with a lack of accurate diagnostic tests. Development of an effective vaccine is highly desirable. This however requires better characterization of the natural immune response of this neglected but important disease. Here we implement a novel IFN-γ ELISpot assay as a tool for studying O. tsutsugamushi induced cellular immune responses in an experimental scrub typhus rhesus macaque model and human populations. Whole cell antigen for O. tsutsugamushi (OT-WCA) was prepared by heat inactivation of Karp-strain bacteria. Rhesus macaques were infected intradermally with O. tsutsugamushi. Freshly isolated peripheral blood mononuclear cells (PBMC) from infected (n = 10) and uninfected animals (n = 5) were stimulated with OT-WCA, and IFN-γ secreting cells quantitated by ELISpot assay at five time points over 28 days. PBMC were then assayed from people in a scrub typhus-endemic region of Thailand (n = 105) and responses compared to those from a partially exposed population in a non-endemic region (n = 14), and to a naïve population in UK (n = 12). Mean results at Day 0 prior to O. tsutsugamushi infection were 12 (95% CI 0-25) and 15 (2-27) spot-forming cells (SFC)/106 PBMC for infected and control macaques respectively. Strong O. tsutsugamushi-specific IFN-γ responses were seen post infection, with ELISpot responses 20-fold higher than baseline at Day 7 (mean 235, 95% CI 200-270 SFC/106 PBMC), 105-fold higher at Day 14 (mean 1261, 95% CI 1,097-1,425 SFC/106 PBMC), 125-fold higher at Day 21 (mean 1,498, 95% CI 1,496-1,500 SFC/106 PBMC) and 118-fold higher at Day 28 (mean 1,416, 95% CI 1,306-1,527 SFC/106 PBMC). No significant change was found in the control group at any time point compared to baseline. Humans from a scrub typhus endemic region of Thailand had mean responses of 189 (95% CI 88-290) SFC/106 PBMC compared to mean responses of 40 (95% CI 9-71) SFC/106 PBMC in people from a non-endemic region and 3 (95% CI 0-7) SFC/106 PBMC in naïve controls. In summary, this highly sensitive assay will enable field immunogenicity studies and further characterization of the host response to O. tsutsugamushi, and provides a link between human and animal models to accelerate vaccine development.
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spelling doaj-art-519ad9d377d8468b99371b9afaff65112025-08-20T02:03:39ZengPublic Library of Science (PLoS)PLoS Neglected Tropical Diseases1935-27271935-27352017-09-01119e000584610.1371/journal.pntd.0005846Strong interferon-gamma mediated cellular immunity to scrub typhus demonstrated using a novel whole cell antigen ELISpot assay in rhesus macaques and humans.Manutsanun SumonwiriyaDaniel H ParisPiyanate SunyakumthornTippawan AnantatatKemajittra JenjaroenSuchintana ChumsengRawiwan Im-ErbsinAmpai TanganuchitcharnchaiSuthatip JintawornStuart D BlacksellFazle R ChowdhuryBarbara KronsteinerPrapit TeparrukkulRobin L BurkeEric D LombardiniAllen L RichardsCarl J MasonJames W JonesNicholas P J DaySusanna J DunachieScrub typhus is a febrile infection caused by the obligate intracellular bacterium Orientia tsutsugamushi, which causes significant morbidity and mortality across the Asia-Pacific region. The control of this vector-borne disease is challenging due to humans being dead-end hosts, vertical maintenance of the pathogen in the vector itself, and a potentially large rodent reservoir of unclear significance, coupled with a lack of accurate diagnostic tests. Development of an effective vaccine is highly desirable. This however requires better characterization of the natural immune response of this neglected but important disease. Here we implement a novel IFN-γ ELISpot assay as a tool for studying O. tsutsugamushi induced cellular immune responses in an experimental scrub typhus rhesus macaque model and human populations. Whole cell antigen for O. tsutsugamushi (OT-WCA) was prepared by heat inactivation of Karp-strain bacteria. Rhesus macaques were infected intradermally with O. tsutsugamushi. Freshly isolated peripheral blood mononuclear cells (PBMC) from infected (n = 10) and uninfected animals (n = 5) were stimulated with OT-WCA, and IFN-γ secreting cells quantitated by ELISpot assay at five time points over 28 days. PBMC were then assayed from people in a scrub typhus-endemic region of Thailand (n = 105) and responses compared to those from a partially exposed population in a non-endemic region (n = 14), and to a naïve population in UK (n = 12). Mean results at Day 0 prior to O. tsutsugamushi infection were 12 (95% CI 0-25) and 15 (2-27) spot-forming cells (SFC)/106 PBMC for infected and control macaques respectively. Strong O. tsutsugamushi-specific IFN-γ responses were seen post infection, with ELISpot responses 20-fold higher than baseline at Day 7 (mean 235, 95% CI 200-270 SFC/106 PBMC), 105-fold higher at Day 14 (mean 1261, 95% CI 1,097-1,425 SFC/106 PBMC), 125-fold higher at Day 21 (mean 1,498, 95% CI 1,496-1,500 SFC/106 PBMC) and 118-fold higher at Day 28 (mean 1,416, 95% CI 1,306-1,527 SFC/106 PBMC). No significant change was found in the control group at any time point compared to baseline. Humans from a scrub typhus endemic region of Thailand had mean responses of 189 (95% CI 88-290) SFC/106 PBMC compared to mean responses of 40 (95% CI 9-71) SFC/106 PBMC in people from a non-endemic region and 3 (95% CI 0-7) SFC/106 PBMC in naïve controls. In summary, this highly sensitive assay will enable field immunogenicity studies and further characterization of the host response to O. tsutsugamushi, and provides a link between human and animal models to accelerate vaccine development.https://journals.plos.org/plosntds/article/file?id=10.1371/journal.pntd.0005846&type=printable
spellingShingle Manutsanun Sumonwiriya
Daniel H Paris
Piyanate Sunyakumthorn
Tippawan Anantatat
Kemajittra Jenjaroen
Suchintana Chumseng
Rawiwan Im-Erbsin
Ampai Tanganuchitcharnchai
Suthatip Jintaworn
Stuart D Blacksell
Fazle R Chowdhury
Barbara Kronsteiner
Prapit Teparrukkul
Robin L Burke
Eric D Lombardini
Allen L Richards
Carl J Mason
James W Jones
Nicholas P J Day
Susanna J Dunachie
Strong interferon-gamma mediated cellular immunity to scrub typhus demonstrated using a novel whole cell antigen ELISpot assay in rhesus macaques and humans.
PLoS Neglected Tropical Diseases
title Strong interferon-gamma mediated cellular immunity to scrub typhus demonstrated using a novel whole cell antigen ELISpot assay in rhesus macaques and humans.
title_full Strong interferon-gamma mediated cellular immunity to scrub typhus demonstrated using a novel whole cell antigen ELISpot assay in rhesus macaques and humans.
title_fullStr Strong interferon-gamma mediated cellular immunity to scrub typhus demonstrated using a novel whole cell antigen ELISpot assay in rhesus macaques and humans.
title_full_unstemmed Strong interferon-gamma mediated cellular immunity to scrub typhus demonstrated using a novel whole cell antigen ELISpot assay in rhesus macaques and humans.
title_short Strong interferon-gamma mediated cellular immunity to scrub typhus demonstrated using a novel whole cell antigen ELISpot assay in rhesus macaques and humans.
title_sort strong interferon gamma mediated cellular immunity to scrub typhus demonstrated using a novel whole cell antigen elispot assay in rhesus macaques and humans
url https://journals.plos.org/plosntds/article/file?id=10.1371/journal.pntd.0005846&type=printable
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