Gregory Karadjian

Gregory Karadjian
Agence Nationale de Sécurité Sanitaire de l'Alimentation, de l'Environnement et du Travail | ANSES · Maisons-Alfort Laboratory for Animal Health

Doctor of Philosophy

About

46
Publications
5,057
Reads
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265
Citations
Additional affiliations
October 2015 - present
Agence Nationale de Sécurité Sanitaire de l'Alimentation, de l'Environnement et du Travail
Position
  • Researcher
Description
  • Development of new tools for the detection of parasitic nematode Trichinella
January 2015 - September 2015
ANSES
Position
  • PostDoc Position
Description
  • Development of innovative tools to fight against parasitic nematodes digestive
September 2011 - September 2014
Muséum National d'Histoire Naturelle
Position
  • PhD Student
Description
  • Experimental and natural coinfections : host-parasite interactions in birds (Haemosporidia of raptors) and in a murine model (Plasmodium sp. / Litomosoides sigmodontis)

Publications

Publications (46)
Article
Full-text available
The parasitic nematode Trichinella has a special relationship with its host as it has a unique intracellular location within the feeder cell which is a structure derived from skeletal muscle fiber. It has been proposed that “parakines” secreted by Trichinella larvae serve as messengers to implement communication between the parasite and the muscle...
Article
Parasites have developed many strategies to ensure their development, multiplication, and dissemination, including the use of reservoir hosts that are often nondomesticated species. Despite drastic reductions in their populations, wild birds remain widespread worldwide and could constitute some of these reservoirs. We focused on the identification...
Article
Full-text available
Aptamers are small nucleic acids that fold in a three-dimensional conformation allowing them to bind specifically to a target. This target can be an organic molecule, free or carried in cells or tissues, or inorganic components, such as metal ions. Analogous to monoclonal antibodies, aptamers however have certain advantages over the latter: e.g., h...
Chapter
Parasites are complex pathogens, particularly in terms of their antigens, which can vary with life cycle stage and location in the host. Three main biological stages in Trichinella genus were described but it is an oversimplification of the complex Trichinella cycle. Trichinella antigens and immunodominant epitopes have been studied using various s...
Chapter
Trichinellosis is a worldwide zoonosis caused by parasitic nematodes of the genus Trichinella and remains an important zoonotic disease on a global basis. The man becomes contaminated when eating undercooked meat containing larvae of the nematode. The disease is a feverish myositis and can be a serious disease with severe complications such as myoc...
Article
Full-text available
To ensure that meat from livestock and game is safe for human consumption, European legislation lays down rules for mandatory testing. Helminth larvae are a category of zoonotic foodborne pathogens that can contaminate meat. Among helminths, the only zoonotic nematode regulated in Europe regarding meat inspection is Trichinella spp.. It is precisel...
Article
Full-text available
Background: More than a hundred species of mammals, birds, and reptiles are infected by nematodes of the Trichinella genus worldwide. Although, Trichinella spp. are widely distributed in neighboring countries including Georgia, Azerbaijan, Turkey and Iran, no study was conducted in Armenia since 1980’s. Methods: In 2017-2018, five muscle samples b...
Article
Full-text available
Trichinellosis is a rare parasitic zoonosis in the European Union. Meat from backyard pigs was the common source for a trichinellosis outbreak caused by Trichinella spiralis, which occurred in France and Serbia in the beginning of 2017. An epidemiological study was conducted in France and Serbia to determine the extent of the outbreak, to identify...
Article
The foodborne zoonotic nematode Trichinella spp. can cause human trichinellosis when raw or undercooked contaminated meat is ingested. To date, twelve Trichinella species/genotypes have been described. According to EU regulation any Trichinella larvae detected during mandatory routine examinations need to be identified at a species level by a compe...
Article
A survey of the haemoparasites present in the blood of falcons collected in three wildlife hospitals in France where wild raptors found wounded or sick are treated, and released, was conducted between June 2011 and August 2014. Haemoproteus, Plasmodium, Trypanosoma and Leucocytozoon were found. The Haemoproteus were the most frequent haematozoa pre...
Article
Full-text available
Here, we report new insights on the erythrocytic murine parasite Anthemosoma garnhami, which was first described from Ethiopia in 1969. Its classification has been debated for years, as this parasite presents some intermediate characters between the Haemosporidia and the Piroplasmida. Based on electron-microscopy, immunological, biochemical and dru...
Article
Full-text available
In order to identify Trichinella at the species level, the commonly used test is a multiplex PCR, allowing the discrimination of nine out of the twelve taxa described so far. This test is based on five primer pairs amplifying fragments of the large subunit rDNA. Each taxon produces one or two bands of different sizes, resulting in a specific band p...
Article
Full-text available
Author summary Mansonella perstans is a widespread human filarial parasite in Africa responsible for pleural and peritoneal cavity filariasis. Compared to other filarial parasites such as Wuchereria bancrofti, Brugia malayi, and Loa loa, the biology of M. perstans is poorly known. The blood-feeding vectors inject infective larvae (L3) into the host...
Data
L3 tissue repartition. Overview from [2,11,12,42,43] and current data (from Fig 1). L3 were recovered from either mice, jirds or cotton rats; number of recovered L3 were normalized as F/L3 and pooled per time point. SC: subcutaneous tissue; Lymph: lymph nodes; Pleural: pleural cavity. (TIF)
Article
Full-text available
Haemosporidia parasites have mostly and abundantly been described using mitochondrial genes, and in particular cytochrome b (cytb). Failure to amplify the mitochondrial cytb gene of Nycteria parasites isolated from Nycteridae bats has been recently reported. Bats are hosts to a diverse and profuse array of Haemosporidia parasites that remain largel...
Article
Full-text available
Our knowledge and control of the pathogenesis induced by the filariae remain limited due to experimental obstacles presented by parasitic nematode biology and the lack of selective prophylactic or curative drugs. Here we thought to investigate the role of neutrophils in the host innate immune response to the infection caused by the Litomosoides sig...
Data
Blood neutrophils number in the 6 hours following infection. Total numbers of neutrophils (millions of cells per mL of blood) before (H0) and after SC infection (2 and 6 hours, H2 and H6) with 40 infective larvae of wt (white bars) and Cxcr4+/1013 (black bars) mice. Results are expressed as mean +/- SEM. T-tests *: p < 0.05, ns = not significant. (...
Data
Visualization of NET-like structures in the skin of mutant mice 6 hours following infection. Images captured from scanned skin sections from mutant mice (+/1013) and their normal littermate (wt) that were collected from the inoculation site 6 hours after infection (Inf) or injection of RPMI media (Ctrl). Two skin sections are shown (A and B) for ea...
Data
A model of L. sigmodontis filarial infection in mice: Time course and invasion routes. Recovery rate in pleural cavity (% of inoculum, in green) and total PleCs (X106 cells, in blue) in resistant and susceptible mice in the course of the filarial infection adapted from [4, 39, 47, 77–79]. Hypothetical location and migration path of the parasite upo...
Data
Blood number of neutrophils the first 5 days following infection. Total numbers of blood neutrophils (millions of cells per mL of blood) measured every day the first 5 days following SC injection of 40 infective larvae in wt and Cxcr4+/1013 mice (n = 5). Means were compared at each time point for each mice, t-tests, ***: p < 0.001. (TIF)
Data
Parasitic success is dramatically reduced in Cxcr4+/1013 mutant mice as early as day 8 post infection. L. sigmodontis (40 larvae) were subcutaneously injected into wt and Cxcr4+/1013 C57BL/6 mice. Worms were harvested in the pleural cavity of the mice 8 days p.i. and counted (nF). Results are expressed as mean +/- SEM, n = 5 mice per group, MW-test...
Data
Cxcr4+/1013 neutrophils exhibit a gain of Cxcr4-dependent chemotaxis. A: Chemotaxis of murine BM-derived neutrophils from wt and Cxcr4+/1013 control mice and their infected counterparts (at 20 days p.i) in response to Cxcl1 (50nM), Cxcl12 (10nM) or Cxcl12 (10nM) + AMD3100 (200μM). Migrating neutrophils recovered in the lower chamber were gated as L...
Data
Total number of PleCs and their composition. A: Cells were harvested and counted at necropsy at 20 days p.i. upon flushing the pleural cavity of non-infected (wt ctrl and +/1013 ctrl) and infected (wt inf and +/1013 inf) mice. Cells were then stained with F4/80-APC, Siglec-F-PE, Ly6G-FITC, CD3-PE and B220-FITC directed antibodies. B: Gating strateg...
Data
Steady state levels and recruitment of cells in the skin upon filariae inoculation. Skin sections were collected before inoculation (control mice, Ctrl) or excised from the inoculation site 6 hours p.i. (Infected mice, Inf), embedded in paraffin and stained with H&E for the visualization of eosinophils (A), anti-F4/80 for macrophages (B) or toluidi...
Data
Cxcl12 levels in dermal stroma of wt and mutant Cxcr4+/1013 mice at steady state and 6 hours following infection. Images captured from scanned skin sections from mutant mice and their wt littermate that were collected from the inoculation site 6 hours after infection (Infected H6 p.i.) or injection of RPMI media (untreated). Skin sections were embe...
Data
Blood number of neutrophils throughout the course of filarial infection (Days 1–40) following IV or SC challenges. Raw blood neutrophils counts from the experiments presented in Fig 2 panel C. Neutrophil counts (millions of cells per mL of blood) were obtained from mice either IV inoculated with 40 infective larvae (IV L3 wt and IV L3 +/1013, n = 5...
Article
Full-text available
Life cycles and molecular data for terrestrial haemogregarines are reviewed in this article. Collection material was re-examined: Hepatozoon argantis Garnham, 1954 in Argas brumpti was reassigned to Hemolivia as Hemolivia argantis (Garnham, 1954) n. comb.; parasite DNA was extracted from a tick crush on smear of an archived slide of Hemolivia stell...
Presentation
Full-text available
Filariases are chronic diseases affecting 200 million people worldwide. Despite considerable effort to reduce disease burden, filarial infections remain a major public health problem requiring new therapeutic approaches. In our study, we used Litomosoides sigmodontis as a well-established murine model of filarial infections. We have previously show...
Presentation
Full-text available
Filariases are chronic diseases affecting 200 million people worldwide. Despite considerable effort to reduce disease burden, particularly through mass drug administration programs, filarial infections remain a major public health problem requiring new therapeutic approaches. In our study, we used Litomosoides sigmodontis as a well-established muri...
Data
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Presentation
Full-text available
Les filarioses (filarioses lymphatiques, onchocercose, loase) sont des maladies chroniques affectant 200 millions de personnes dans le monde. Malgré des efforts considérables pour limiter leur impact, le développement de résistances aux traitements et l'absence de macrofilaricides justifient la recherche de nouvelles approches thérapeutiques. C’est...
Article
Full-text available
Haemoproteus ilanpapernai Karadjian and Landau n. sp. from the Spotted Wood Owl, Strix seloputo, in Singapore is described from material from Ilan Paperna's collection of slides. The species was previously identified as Haemoproteus syrnii (Mayer, 1910). However, comparisons between the material from Strix seloputo and our own material from Strix a...
Article
Full-text available
Infection with multiple parasite species is clearly the norm rather than the exception, in animals as well as in humans. Filarial nematodes and Plasmodium spp. are important parasites in human public health and they are often co-endemic. Interactions between these parasites are complex. The mechanisms underlying the modulation of both the course of...
Article
Full-text available
In France, Haemoproteus syrnii is frequently found in the Tawny Owl, Strix aluco. Additional and complementary features of this species, and in particular the characteristics of volutin, are presented. The authors consider the volutin granules as constant in a given species, and discuss their taxonomic value. These cytoplasmic inclusions appear ear...
Poster
Full-text available
Blood smears of Tawny owls, Strix aluco, from three different localities in France were examined and revealed the presence of Haemoproteus syrnii. The prevalence was different in adults (60%) and in juveniles (3%). In this study, we present additional morphological features of this species, in particular the type and the characteristics of the volu...
Article
Full-text available
Symbiotic associations between eukaryotes and microorganisms are frequently observed in nature, and range along the continuum between parasitism and mutualism. The genus Wolbachia contains well-known intracellular bacteria of arthropods that induce several reproductive phenotypes that benefit the transmission of the bacteria. Interestingly, Wolbach...
Article
Full-text available
Four species of Haemoproteidae were found in Pteropus alecto Temminck, 1837 in Queensland, Australia: i) Johnsprentia copemani, Landau et al., 2012; ii) Sprattiella alecto gen. nov., sp. nov., characterised by schizonts in the renal vessels; iii) Hepatocystis levinei, Landau et al., 1985, originally described from Pteropus poliocephalus Temminck, 1...

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