Research – Page 3 – Institut Pasteur de Nouvelle-Calédonie

10 March 201724 July 2018

InfraVec2

Acronym: INFRAVEC 2	Research Infrastructure Program on insect vectors of human and animal disease
Principal investigator	Institut Pasteur
Focal point IPNC	Nicolas Pocquet,
Collaborators at IPNC	Myrielle Dupont-Rouzeyrol, Olivia O’Connor, Morgane Pol, Sosiasi Kilama
Other Collaborators	24 consortium partners (IP, UG, POLOGGB, IRD, IPNC, CUNI, CIRAD, Imperial, IRTA, EMBL, TPI, CAA, Trop IQ, MPIIB, FORTH, RUMC, UNS-FA, UZH, LSTM, IPD, USTTB, HSeT, WU, CNRFP).
Total budget of project	10 000 000 €	Budget devoted to IPNC: 78 860 €
Funding	European Commission Horizon 2020
Timeline	Start date: March 2017		End date: 2020
Context
Insect vectors transmit parasitic diseases such as malaria and leishmaniasis, and viral infections such as chikungunya, dengue, Zika, Japanese encephalitis and yellow fever. The 24 consortium partners hold the major European biosecure insectaries for experimental infection and containment of insect vectors under Containment Level 2 and 3 (CL2/CL3) conditions, other key insect vector facilities, and include front-line field sites in Africa, the Pacific, and the Americas.
Objectives
The Infravec2 project provides research resources and access to key infrastructures for insect vector biology at no cost to the end-user. The goal is to accelerate European research in insect vector biology research, and to develop new vector control measures targeting the greatest threats to human health and animal industries.
Methods
As part of this project, IPNC will provide access to its Level 2+ laboratory for experimental infection with Aedes aegypti, and to provide dead mosquitoes (Ae. aegypti or Culex quinquefasciatus) or eggs of Ae. aegypti. IPNC is also in charge of creating a reference strain of Ae. aegypti whose microbiota will be characterized at the beginning of the breeding and during the generations.
Perspectives
Infravec2 will improve the exploitation of European vector infrastructures for research and public health, and will develop other innovative methodologies and technologies.

24 July 20168 September 2022

Maldi-tof Leptospire identification

*Maldi-Tof identification of Leptospira* spp.**
Principal investigator	Cyrille Goarant
Focal point IPNC	Dominique Girault, Cyrille Goarant
Collaborators at IPNC	Roman Thibeaux, Julien Colot
Other Collaborators	Anna Rettinger, Faculty of Veterinary Medicine, LMU Munich, Germany
Total budget of project	1 000 euros	Budget devoted to IPNC : NA
Funding	IPNC
Timeline	Start date: 2015		End date: 2018
Context
IPNC has implemented MALDI-ToF mass spectrometry for routine identification of bacterial isolates. We aimed to use this system to identify bacteria of the genus Leptospira.
Objectives
The objectives were to create a database of mass spectra of reference strains of the genus Leptospira and then to use it to control the identification of strains used for MAT serology as well as unknown isolates.
Methods
A bibliographic review identified 3 teams that had a mass spectra database of Leptospira spp. The corresponding authors of the articles were asked to share their database. Dr. Anna Rettinger (University of Munich) agreed to transmit her reference spectra. We have also created reference spectra of known collection strains belonging to different species. Unknown (patient isolates) or known strains (from the MAT serology panel) were then identified blindly.
Results
The preliminary tests made it possible to optimize the technique of preparation of the leptospires for reading their mass spectrum on the Maldi-Tof Bruker. The reference spectra of 57 strains representing all 22 known Leptospira species were created and grouped into a dedicated “research” database. Blind analysis of strains shows very good reliability for species-level identification, but insufficient precision to identify individual strains used as antigens for MAT serology. The strains isolated from patients were properly identified at the species-level with high scores considered as diagnostic.
Perspectives
The reference spectrum of Leptospira venezuelensis (currently being described) will also be created. The transfer of the MALDI-TOF and computer breakdowns slowed down the work. This database will be incremented with novel species and used to identify unknown isolates. Threshold scores for species identification will be determined.
Valorisation
These data should be included in a draft publication on the identification of leptospires.

23 July 20168 September 2022

Leptospira survival in water

The survival of pathogenic leptospires in nutrient-poor water: towards a better understanding of the environmental reservoir of leptospirosis
Principal investigator	Emilie Bierque
Focal point IPNC	Emilie Bierque, Cyrille Goarant
Collaborators at IPNC	Marie-Estelle Soupé-Gilbert, Sophie Geroult
Total budget of project	8 300 euros	Budget devoted to IPNC: NA
Funding	IPNC
Timeline	Start date: 2016		End date:2018
Context
The transmission of leptospirosis to humans occurs via exposure to virulent leptospires through contact with urine or tissues of infected animals, most often indirectly via a hydrotelluric reservoir. However, the factors determining the survival of pathogenic leptospires in the environment remain very poorly known.
Objectives
The objective is to describe the survival of leptospires in waters of different mineral compositions.
Methods
We used 0.1µm filter-sterilized water to study the effect of the ionic composition of the waters without the complex interactions that could occur in a complex microbiota and prevent precipitation of salts, which would occur during autoclaving. Waters were dispensed into 50-mL plastic culture flasks with 2 sterile glass slides to assess the adhesion of leptospires and observe possible morphological changes. Leptospires were seeded in each flask at a final concentration of 10⁶ Leptospires / mL. The culture flasks were incubated at 30 ° C in the dark. After various incubation times, individual flasks are used to assess leptospiral counts, viability, cultivability and virulence, for a maximum of 2 years.
Results
After 12 months of experimentation, results reveal different survival rates depending on water, observed from 30 days post-incubation on. We noticed different outcomes between Leptospira strains only for the most mineralized water. Two waters appear to allow a better survival for 3 of the 4 Leptospira strains studied. Furthermore, the most mineralized water seems to become supportive for the survival of one of the strains after one year of experimentation. The 3 strains remain alive and virulent (for pathogenic ones) during at least 9 months in water while the forth strain died after only 2 days. Microscopic techniques allow observing cell aggregates formation as of 60 days post-incubation for pathogens and as early as 2 days for the saprophytic stain.
Prospects
Our study will help identify the ionic composition of the water that favours or compromise the survival of leptospires and thus acquire important data on the survival and maintenance of virulence of leptospires in nutrient-poor conditions.
Valorisation
Mélanie Faure, L2 student at University of New Caledonia made a 2-month training period on this subject. Bierque E, Soupé-Gilbert ME, Geroult S, Thibeaux R and Goarant C. Leptospira survival in freshwater microcosms. Poster at the ILS conference, Palmerston North, NZ, November 2017.