Posters_sstmp

SSTMP Posters
168
Alveolar echinococcosis: in vitro studies and experimental investigations in
vivo identify potential novel treatment option
A Hemphil [1]
[1]Institute of Parasitology, University of Bern, Bern, Switzerland
For the chemotherapy of cystic (CE) and alveolar echinococcosis (AE), albendazole
and mebendazole are presently used for the treatment of non-surgical cases and as
a supplementary treatment prior and post-surgery. However, in AE these
benzimidazoles do not appear to be parasiticidal in vivo. In addition, failures in drug
treatments as wel as the occurrence of side effects have been reported, leading to
discontinuation of treatment or to progressive disease. New drugs are needed to cure
AE and CE, which must be regarded as neglected diseases. Compounds that are
currently being considered to represent novel chemotherapeutical treatment options
include broad-spectrum anti-infective or anti-cancer drugs, drugs that interfere in the
Echinococcus signal ing pathways, and drugs identified through in silico approaches
exploiting the E. multilocularis genome information.
Prerequisites to perform efficient in vitro screenings are, (i) optimized large scale in
vitro metacestode culture systems, and (ii) reliable assays that al ow higher
throughput primary drug testing against metacestodes. In addition, access to a large
col ections of potential y interesting compounds is important. More recently, in vitro
screening in our laboratory has lead to the identification of several drugs or drug
classes, most notably mefloquine-, ozoid- and pentamidine-derivatives, which show
interesting capacities to kil the metacestodes. Studies in the mouse model have
demonstrated the efficacy of oral application of the anti-malarial compound
mefloquine in vivo, and the pentamidine-derivative DB1127, demonstrating that these
drugs, or derivatives thereof, could serve as a supplement to the currently very
limited arsenal of anti-echinococcal compounds. In addition, investigations have been
carried out that lead to the identification of a mefloquine-target in Echinococcus and
explore the mechanism of action of mefloquine in the metacestode stage.
169
Avian malaria and ist prevention strategies in the Zoo Basel

N. Cereghetti [1], C. Wenker [2], S. Hoby [2], P. Mül er [1], H. Marti [1], C. Lengeler
[1]
[1]Swiss Tropical and Public Health Institute, Basel, Switzerland
[2]Zoo Basel, Basel, Switzerland
Avian malaria is causing high mortality rates in penguins. To reduce the malaria
infection rates of the Black-footed penguins (Spheniscus demersus) and other birds
in the zoo of Basel mosquito-prevention strategies are required. Mosquito infection
rates and abundance were monitored. Adult mosquitoes were col ected monthly from
May to September 2011. The mosquito species were identified and a subsample was
used to determine the infection status using a nested PCR. Mosquito larvae were
sampled from al water bodies in and around the zoo during the same time period.
Blood samples from 23 S. demersus were col ected in September 2011 to determine
the prevalence rate of Plasmodium spp. Blood samples from 47 other zoo birds and
wild birds were examined for Plasmodium spp. from March until November 2011.
14'124 adult mosquitoes belonging to 8 different species were captured from which
>99% were Culex pipiens / Culex torrentium. The prevalence rate of Plasmodium
and/or Haemoproteus infections in the mosquitoes were 7.3% in July, 4.2% in August
and 5.2% in September. 62 water bodies were identified inside the zoo. Monthly 16
to 19 of them were found positive for mosquito larvae. Two S. demersus and one
Snowy Owl were harbouring Plasmodium relictum infections. Although prevalence of
infected mosquitoes was high and mosquitoes present in great numbers, prevalence
of Plasmodium spp. in birds was very low. This is probably due to the
chemoprophylaxis given to the birds. To reduce the mosquito population, breeding
sites inside the zoo should be control ed.
170
Monitoring gametocyte prevalence in field surveys

R Amstutz [1], S Javati [1], F Mwingira [1], D Muel er [1], I Felger [1]
[1]Swiss TPH, Basel, Switzerland
Transmission of malaria depends on the presence of gametocytes, the mature sexual
stages of Plasmodium parasites, in the human peripheral blood. Measurements of
gametocyte prevalence rates may serve as a tool to monitor the success of
antimalarial interventions. This is of particular importance in the context of renewed
efforts to eliminate malaria. In areas of moderate malaria transmission, P. vivax
prevalence exceeds that of P. falciparum. P. vivax is therefore a prime target for
intensified interventions, for which monitoring tools are warranted.
In cross-sectional samples from 315 Papua New Guinean children aged 5-10 years
we have validated and compared different methods for sampling RNA for population
wide studies on gametocyte prevalence. Three sampling methods were tested in
paral el: whole blood into RNAprotect (Qiagen), whole blood on Whatman 3MM
paper stored in TRIzol reagent, and whole blood on treated Whatman FTA filter
cards. RNA was extracted using Qiagen RNeasy Plus Minikit. Sequential qRT-PCR
analyses were performed to gain prevalence data for asexual parasites, based on the
detection of 18SrRNA, and for sexual stages, based on pfs25 and pvs25 assays, for
P. falciparum and P. vivax parasites, respectively.
Sampling and storing finger prick blood in RNAprotect solution was found to be most
sensitive and most suitable for high sample throughput. Whatmann 3MM filter papers
in TRIzol reagent showed clearly reduced sensitivity and the procedure was
laborious and contamination prone. Removal of RNA from Whatman FTA cards was
inefficient and not suitable for high throughput.
Prevalence of asexual parasite in our asymptomatic study participants was 40.6% for
P. falciparum and 38.4 % for P. vivax. Of 128 P. falciparum positive samples, 31
(24.2%) carried gametocytes. Of 121 P. vivax positive samples 47 (38.8%) were
gametocyte positive.
This finding reflects biological differences in gametocyte production among the two
species. In the same hosts and with similar overal prevalence of both species,
gametocyte prevalence was substantial y higher for P. vivax than for P. falciparum.
General y P. vivax gametocytes are expected to occur early in an infection. The fact
that P. vivax gametocytemia was detected only in 38.8% of al P. vivax positive
samples is a consequence of our extremely sensitive detection of asexual parasites
based on 18SrRNA transcripts combined with a less sensitive detection of
gametocyte-specific pvs25 transcripts.
171
Proteomics of secretory organelles in Giardia lamblia

P Wampfler [1], C Spycher [1], V Tosevski [2], P Nanni [3], A Hehl [1]
[1]Institute of Parasitology, University of Zürich, Zürich, Switzerland
[2]FACS Core Facility, University of Zürich, Zürich, Switzerland
[3]Functional Genomics Center Zürich, University of Zürich, Zürich, Switzerland
Background: The protozoan G. lamblia is the leading cause for non-bacterial diarrhea
in humans and animals world-wide causing significant morbidity and economic loss.
For transmission to a new host, motile Giardia trophozoites differentiate to cysts, thus
secreting a protective extracel ular matrix. A most unusual fact is that Giardia has no
typical Golgi apparatus to organize regulated secretion of this material. Instead,
differentiating cel s generate specialized organel es termed encystation-specific
vesicles (ESVs), which act as delay compartments to al ow accumulation,
posttranslational maturation and sorting of the cyst wal material (CWM). However,
ESV genesis and maturation are poorly understood.
Aim: The aim of our work is the identification of the protein composition of ESVs and
their associated cargo. This wil serve as a basis for subsequent functional analysis
of these organel es.
Methods: Previous attempts to reveal the organel e proteome with conventional
methods yielded proteomic datasets which were enriched in organel e-specific
proteins but stil contained a high level of contaminating proteins. Here, we present a
novel approach based on simultaneous sorting of fluorescence tagged ESVs and a
second set of organel es fol owed by mass spectrometry (MS) identification of
organel e proteins. False-positive candidates are eliminated in silico from the
corresponding protein datasets by a subtractive approach, al owing for enrichment of
ESV-specific protein candidates. Selected candidates wil be validated using cel
biological and biochemical strategies.
Results: By successful y establishing a FACS-based organel e sorting protocol and
subsequent MS analysis of enriched fractions we reached several key milestones in
this project, resulting in a highly informative ESV-specific proteomic dataset. We are
currently validating the final ESV protein dataset by in silico annotation and selection
of candidates for subcel ular localization studies. This is an important first step
towards a complete picture of ESV cargo proteins and the temporal and spatial
distribution of organel e-associated factors.
Conclusion: With this novel approach we are wel on the way to unraveling the
complete composition of ESVs and their cargo, which serves as a basis for the
investigation of posttranslational modifications, sorting and targeting of the CWM.
With our work we aim to contribute to the establishment of a comprehensive model
for cyst wal formation.
172
Rabies vaccination coverage, Echinococcus and Leishmania prevalences in
the dog population of Bamako, Mali.
S Mauti 1,2, E Schel ing 1,2, J Hattendorf 1,2, F Grimm 3, S Tembeley 4, A Traoré 4, F
Cliquet 5, J Zinsstag 1,2
(1) Swiss Tropical and Public Health Institute, Basel, Switzerland (2) University of Basel, Basel, Switzerland (3) Institute of Parasitology, University of Zurich, Zurich, Switzerland (4) Laboratoire Central Vétérinaire, Bamako, Mali (5) ANSES, Nancy Laboratory for Rabies and Wildlife, WHO Col aborating Centre for Research and Management in Zoonoses Control, OIE Reference Laboratory for Rabies, European Union Reference Laboratory for Rabies, European Union Reference Laboratory for Rabies Serology, Nancy, France Aims: Within the research program Integrated Control of Neglected Zoonoses (ICONZ), we investigated prevalences and risk factors of canine echinococcosis and leishmaniasis as wel as dog rabies vaccination coverage in urban Mali. To date, there is little known about canine zoonoses in many West African countries. Our results wil contribute to development of a targeted elimination program. Methods: Overal , 372 owned dogs were identified in Bamako through two surveys of 2940 households. Blood, fur and faecal samples were col ected for analysis including microscopic, immunodiagnostic and molecular methods. To obtain basic dog demography data and to describe characteristics of dog-keeping, 277 dog-keeping households were fol owed, when possible, through telephone interviews every four months for two years. Preliminary Results: Out of 101 col ected samples analysed to date, one intestinal E. granulosus and 28 Taenia infections have been identified, but specific anti-Leishmania antibodies have not been detected. A total of 28 dogs (17%) have been vaccinated against rabies. Out of the 18 sera from vaccinated dogs tested, 11 harboured positive neutralising rabies antibody titres. Current conclusions: The 22 reported human rabies cases in Bamako from 2004 through 2009 indicate that rabies is likely the most important zoonosis of urban dogs. The results obtained suggest a vaccination coverage approximating 17%, which is insufficient to interrupt virus transmission. A concerted mass vaccination program complementing the efforts of private dog owners would be needed to eliminate dog rabies in Bamako. Acknowledgments: We thank the Integrated Control of Neglected Zoonoses (ICONZ) research program for funding of this project, the field team in Bamako for the great job they did, and a special thanks to al the dog owners for their participation. 173
Testing for Chlamydia trachomatis: time trends in positivity rates in the canton
of Basel-Stadt, Switzerland

C. Schmutz [1], D. Burki [2], F. Käppeli [3], M. Mäusezahl-Feuz [4], D. Mäusezahl [1]
[1]Swiss Tropical & Public Health Institute and University of Basel, Basel, Switzerland
[2]Viol ier AG, Basel, Switzerland
[3]Medica, Medizinische Laboratorien Dr. F. Käppeli, Zürich, Switzerland
[4]Swiss Federal Office of Public Health, Bern, Switzerland
Objectives :
National health statistics report a 2.5-fold increase in laboratory confirmed Chlamydia
trachomatis (CT) cases over the last decade in Switzerland where no CT-screening
programme exists. The interpretation of the data is limited given missing denominator
information. Our objective was to obtain such denominators and describe the
epidemiology of CT in canton Basel-Stadt, Switzerland.
Methods :
Laboratories reporting at least two cases of Chlamydia trachomatis infections from
Basel-Stadt residents to the Swiss Federal Office of Public Health in 2010 were
asked to provide demographic and test related data. CT-positivity rates, defined as
the number of positive tests divided by the total number of tests performed, were
calculated for 2002-2010. The influences of test year, age, sex and laboratory on CT-
positivity was investigated in a multivariable model. Positivity does not represent the
prevalence among the tested population since the denominator may include multiple
tests from the same individual.
Results :
Positivity differed between sexes and age groups. Female and male CT-positivity
rates were 4.7% and 12.6%, respectively. Test year was significantly associated with
test outcome in the multivariable analysis but no time trend was observed.
Discussion/Conclusion :
Our findings suggest that in Basel-Stadt, CT-positivity did not increase between 2002
and 2010. The observed increase of chlamydia cases in the mandatory notification
system of infectious diseases may not represent an epidemiological trend, but is
rather a result of increased testing.
A CT-infection is more often asymptomatic in females. In concert with different health
seeking patterns among males (symptom-based) and females (screening-like routine
check ups), CT-positivity for females represents a prevalence measure while for
males it measures mostly incident infections (thus, resembling incidence).
Consequently, publical y accessible routine health data from the mandatory
notification system on CT infections consist of data of two distinct testing populations.
In contrast to findings from other European countries, the current study which was
limited to a smal part of the country, found no increase in CT-positivity during the
past nine years. A similar analysis using a representative sample should confirm this
finding for the whole of Switzerland
174
Rift Valley Fever in Kenya: Analyses of prevention and control options from a
multisectoral perspective
E. Schel ing1,2, S., Fuhrimann1,2, A. Bitek3, K. Njenga4, T. Randolph5, T. Kimani5
1 Swiss Tropical and Public Health Institute, Basel, 2 University of Basel, 3 Jomo
Kenyatta University of Agriculture and Technology, 4 Kenyan Medical Research
Institute, 5 International Livestock Research Institute, Kenya

Aim: The two recent Rift Val ey Fever (RVF) epidemics in Kenya /1997/1998 and
2006/2007) resulted in severe socio-economic consequences for the country. RVF is
a viral zoonosis and a mosquito-borne disease that affects people, livestock and
wildlife and thus is dealt with by multiple sectors. We address the need for closer
cooperation between the two sectors to al ocate limited resources more appropriately
and to facilitate planning of concerted activities.
Methods: i) Mapping of stakeholders and institutional analysis; i ) Simulation of
different options (combinations of vaccination, sanitary measures, surveil ance,
vector control and awareness campaigns) with an individual-based livestock
demographic model; i i) Economic modeling to estimate costs of control per DALY
averted and costs and benefits to the livestock sector and national economy.
Results:
Up to 28 different agencies are relevant and need to be considered in col aborations
on RVF (and zoonoses in general) prevention and control. The stakeholders go
beyond the line animal and public health sectors, indeed, the most important actor is
not within the health sectors. The baseline and RVF-attributable mortalities can be
simulated and show the losses due to RVF. We can retrieve proportions of livestock
species (age/sex-stratified) and th number of infected slaughtered and sold animals
that represent the highest risk of human infections. Smal ruminants are most likely to
spread the disease through livestock trade. Slaughtered infected sheep are an
important risk factor to human RVF infection. The last outbreak, only considering the
official records, summed up to 4036 DALYs (or 340 / 100'000 corresponding to a fifth
of TB DALYs in the same year). A first cost-benefit analysis based on two
consecutive animal RVF vaccinations one year prior to an outbreak was highly
beneficial in terms of return to investment of the government
Conclusions:
The ratio of susceptible/immune hosts from the model supports the estimation of
immunity levels years after a previous outbreak. It also considers normal and drought
period, which is more realistic for Sahelian pastoral livestock production systems and
is currently fitted to agro-pastoral and smal holder livestock systems. Our results help
to consider best governmental investments regarding the reduction of economic
losses and human morbidity/mortality, which, in return, improves future intersectoral
contingency planning. A narrow scope of traditional One Health actors (health,
livestock and environmental sectors) would weaken the control of zoonoses.
175
Mycobacterium tuberculosis complex Beijing genotype showed association
with drug resistance and relapse in Nepal

Bijaya Mal a (1, 3), B. Shrestha (2), S. Gagneux (1, 3)
1. Department of Medical Parasitology and Infection Biology, Swiss Tropical and
Public Health Institute (Swiss TPH), Basel, Switzerland
2. German Nepal Tuberculosis Project, Kathmandu, Nepal
3. University of Basel, Switzerland
Background: The proper diagnosis and treatment of tuberculosis relies on detection
of drug-resistant Mycobacterium tuberculosis complex (MTBC) strains. Drug resistant
strains may lead to treatment failure and transmission of drug resistant tuberculosis.
Drug resistance and relapse has been associated to Beijing genotype in different
parts of the world. We aimed to explore the MTBC genotypes and association with
drug resistance, and relapse treatment outcome in low multi drug resistance
prevalence, but high-disease incidence setting of Nepal.
Methods: A total of 261 MTBC strains have been genotyped using spoligotyping.
Single nucleotide polymorphism (SNPs) was performed to define the phylogenetic
lineages. Drug resistant mutations for rifampicin and isoniazid were detected by
standard capil ary sequencing methods.
Results: The new tuberculosis patients were 164 (62.84%) and relapsed cases were
74 (28.35%). The two major spoligotypes found were Beijing 82 (31.42%), and
Central Asian strain (CAS1_DELHI) 63(24.14%). The SNP typing of 261 MTBC
isolates showed presence of four phylogenetical y distinct lineages; East-African-
Indian lineage (40.61%), East-Asian lineage (32.18%), Euro-American lineage
(15.71%), and Indo-Oceanic lineage (11.49%). The percentage of relapse
27(32.14%) and any drug resistance for isoniazid or rifampicin 17 (2023%), and
multi-drug resistance 9 (10.71%) was higher in East-Asian Lineage (that includes
"Beijing" Spoligotype family) compared to other lineages.
Conclusions: The MTBC population structure is highly diverse in Nepal, driven by two
major lineages. The Beijing genotype is most predominant cause of tuberculosis in
Nepal. The association with drug resistance indicates that East-Asian lineage may
have a selective advantage with drug resistance and should be regarded as cause of
relapse. Our findings suggest further investigation is needed to understand
transmission of drug resistance and relapses attributed by Beijing genotype.
Keywords:
Tuberculosis, Beijing, drug resistance, relapse
176
PE_PGRS genetic diversity in Mycobacterium tuberculosis is not related to
immune escape
Mireia Coscol á 1, 2 , Richard Copin 3, Salome Seiffert1, 2, Stephanie Birrer1, 2, Daphne Davis 3, Joel Ernst 3 and Sebastien Gagneux 1,2, 1 Swiss Tropical and Public Health Institute, Basel, Switzerland, 2 University of Basel, Basel, Switzerland, 3 New York University School of Medicine, NY, USA, Mycobacterium tuberculosis' strategies to subvert the immune system are largely unknown. One possible mechanism of immune evasion consists in generating escape mutants to decrease the immunogenicity of the pathogen gene products. Contrary to what would be predicted if Mycobacterium tuberculosis complex (MTBC) fol owed such a strategy, recent evidence has shown that human T cel epitopes in human-associated MTBC are evolutionarily hyperconserved and under strong purifying selection (1). However, PE_PGRS genes that are among the most genetical y diverse genes in the otherwise highly conserved MTBC genome were not included in that study (1). The function of most PE_PGRS genes is unknown, but putative antigenic properties have been attributed to these genes, in part because of their high genetic diversity. The objective of this study was to explore whether human T cel recognition is driving the increased genetic diversity in PE_PGRS genes of MTBC. We looked for putative CD4+ and CD8+ T cel epitopes in the 64 annotated-PE_PGRS genes by in silico analyses. Predicted epitopes were asymmetrical y distributed along the PE_PGRS with a preferential localization within the PE domain and no epitopes predicted in the PGRS domain. 27 whole gene sequences (25 PE_PGRS and 2 PE genes lacking PGRS domain) were generated for 95 MTBC strains representative of the global diversity of human-associated MTBC. We found a wide range of genetic diversity among the PE_PGRS gene family, but overal , nucleotide diversity was significantly higher than in the rest of the MTBC genome. The highest genetic diversity was found in the PGRS domain, while the PE domain was more conserved. Different selection pressures were predicted for different members of the gene family. 7 genes were predicted to be under positive selection (dN/dS > 1.5), 9 under purifying selection (dN/dS < 0.6) and 10 genes under neutrality (dN/dS 0.6-1.5). In silico analyses revealed that modifications in the amino acid sequence of mutated PE_PGRS did not affect quantitatively or qualitatively the results of MHC class I and class II epitope predictions. We conclude that the most variable regions of the PGRS genes are predicted not to be recognized by CD4+ and CD8+ T cel s, and that the putative T cel epitopes do not show any evidence for escape mutants. Overal , these results weigh the current ‘dogma' that PGRS diversity results from immune recognition, and reinforce the observation by Comas et al. (1) that MTBC epitopes are in fact hyperconserved. References 1. Comas, I., J. Chakravartti, P. M. Smal , J. Galagan, S. Niemann, K. Kremer, J. D. Ernst, and S. Gagneux. 2010. Human T cel epitopes of Mycobacterium tuberculosis are evolutionarily hyperconserved. Nat Genet 42:498-503. 177
Mefloquine – a novel treatment for Alveolar Echinococcosis

Tatiana Küster, Andrew Hemphil

Institute of Parasitology, Vetsuisse Faculty - University of Berne
Länggassstrasse 122, CH-3012 Berne, Switzerland

Alveolar echinococcosis is caused by the metacestode stage of the fox tapeworm
Echinococcus multilocularis and causes severe disease in the human liver and
occasional y other organs, which is fatal if treatment is unsuccessful. The present
chemotherapy is based on benzimidazoles, which have been found to act
parasitostatic rather than parasiticidal, usual y resulting in lifelong uptake of large
doses of drug. New treatment options are urgently needed but seldom developed
due to the rare occurrence of the disease.[1] An in vitro screening of drugs currently
used for the treatment of other parasitic diseases was performed, by employing an
assay that measures the release of phosphoglucose isomerase by metacestodes
with impaired viability.[2]. The selected candidate, mefloquine, applied in the
prevention and treatment of malaria, showed promising results both in vitro and in
vivo. Intraperitoneal y infected Balb/c mice were treated with mefloquine oral y
(25mg/Kg) or intraperitoneal y for a period of eight weeks. Treatment with mefloquine
administered intraperitoneal y presented a reduction in total parasite burden similar to
that of albendazole oral treatment.[3] Further investigations were made with
intraperitoneal y infected mice and oral application of mefloquine at 25mg/Kg,
50mg/Kg and 100mg/Kg, respectively, for a period of 12 weeks. Treatment with
mefloquine at 100mg/kg twice a week was as effective as treatment with albendazole
(200mg/kg/day). Whether mefloquine treatment acts parasitocidal remains to be
investigated.
We are also interested in how the drug exerts its effects. The mechanism of action of
mefloquine against Plasmodium falciparum is believed to prevent the heme
polymerization to hemozoin in the host red blood cel s, a process that is essential to
the survival of the parasite.[4] Such a mechanism would not explain the action of the
drug against metacestodes, as these are not intracel ular parasites. Affinity
chromatography with a mefloquine-bound matrix fol owed by mass spectrometry of
binding proteins resulted in the identification of the E. multilocularis ferritin as a
mefloquine-binding protein. Ferritins are wel conserved intracel ular proteins
responsible for the storage and transport of iron in a non-toxic form. In order to
validate ferritin as a potential target for mefloquine, experiments employing RNAi are
currently being performed.
1.
Hemphil A, Mül er J. J Helminthol. 2009 Jun;83(2):99-111. Stadelmann B, Schol S, Mül er J, Hemphil A. J Antimicrob Chemother. 2010 Mar;65(3):512-9. 3. Küster T, Stadelmann B, Hermann C, Schol S, Keiser J, Hemphil A. Antimicrob Agents Chemother. 2011 Feb;55(2):713-21. 4. Sul ivan DJ, Matile H, Ridley RG, Goldberg DE. J Biol Chem. 1998 Nov;273(47):31103-7. 178
Different outcomes of protection against Neospora caninum infection after
vaccination with a chimeric antigen in the pregnant and in the non-pregnant
mouse model
Thierry Monney*, Andrew Hemphil

Institute of Parasitology, University of Berne, Länggassstrasse 122, 3012 Bern,
Switzerland
Neospora caninum (Apicomplexa: Eimeriina: Sarcocystidae) is reported as the
leading cause of bovine abortion, thus the disease represents an important veterinary
health problem and is of high economical significance (1;2).
The overal goal of our investigations on N. caninum is to develop a vaccine that
limits both the cerebral infection and the transplacental transmission. Since promising
results were obtained with a combination of the recombinant forms of two microneme
proteins, NcMIC1 and NcMIC3 and one rhoptry protein, NcROP2, in the reduction of
cerebral infection and vertical transmission in infected mice (3), we focused on the
use of these proteins for further vaccination strategies. We created four different
chimeric proteins composed of their respective predicted putative antigenic domains
placed in different order. Balb/C mice were vaccinated with the different antigens
solubilised in saponin and chal enged with 2x106 N. caninum tachyzoites. One of the
chimeric proteins, recNcMIC3-1-R, conferred significant protection against cerebral
infection (4). A second experiment was performed with the protective antigen
(recNcMIC3-1-R) in the pregnant mouse model. Mice were vaccinated, mated, and
chal enged at day 7-9 of gestation. However, no protection against transplacental
transmission and against cerebral infection in the pregnant dams was observed in
the vaccinated group. The vaccine induced a Th2-biased immune response with high
IgG1 and high IL-4 titers in sera. The high IgG1/IgG2a ratio remains true after
vaccination in both models. However a difference was observed in the cytokine
production after chal enge. While the non pregnant mice showed a higher IFN-y/IL-4
ratio, the pregnant mice showed an overal lower cytokine production with a higher
IL-4/IFN-y ratio. The lack of protection observed in the pregnant mouse model was
thought to be due to a modulation of the immune response by the sex hormones
during pregnancy, resulting in a Th2 type immune response, thus hampering the
mixed Th1/Th2- type immune response associated with protection in the non-
pregnant mouse model. In order to counterbalance the strong Th2 response in the
pregnant mice, a third vaccination trial employing Freund's incomplete adjuvant, a
stimulator of cel ular immunity, was planned and is currently in progress. A
comparison of the degrees of protection achieved and the immune responses
observed in the three models wil be presented.

References:
(1) Dubey, J. P. Et al. Clin Microbiol Rev 2007 20:323-367.
(2) Hemphil A, Gottstein B. Int J. Parasitol 2000 30:877-924.
(3) Debache K. et al. Int J Parasitol 2009 39(12):1373-84.
(4) Monney, T. Vaccine 2011 29(40):6967-7


At the crossroads between life and death-Mitosomes and PCD in Giardia
Samuel Rout1, Carmen Faso1, Petra Wampfler1, Vinko Tosevski2, Adrian B. Hehl1 1) Laboratory of Molecular Parasitology, Institute for Parasitology-University of Zürich, Winterthurerstrasse 266a, 8057 Zürich, Switzerland 2) Centre for Microscopy and Image Analysis, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland Programmed cel death in protozoan parasites is emerging as a target for novel therapies to treat some of the most widespread and serious infections of humans and animals alike. The intestinal parasite Giardia lamblia is responsible for ca. 300 mil ion cases a year of water-borne diarrheal disease. Although infected patients harbor mil ions of parasitic cel s attached to intestinal epithelia, inflammatory responses in the gut are surprisingly absent. This suggests that Giardia lamblia possesses the necessary molecular machinery to perform some kind of PCD to suppress host response. To investigate this PCD-related process in vitro, we seek to identify specific and measurable morphological changes on a cel ular and subcel ular level. Fol owing interference of mitosomal protein import, we observed rapid cel deterioration which we suspect to be PCD-related. For this reason, our focus is on mitosomes and on their potential involvement in organized cel death. We are currently characterizing these organel es in terms of their localization and their morphology in living and dying giardial cel s. We are also investigating composition of the protein import machinery at the outer membrane of these organel es using immunoprecipitation techniques. Furthermore, we are developing flow-cytometry based enrichment protocols to determine the mitosomal proteome and identify possible targets for PCD initiation and/or progression.

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