First report of Giardia duodenalis assemblage F in humans and dogs in southern Brazil

The present study aimed to molecularly characterize Giardia duodenalis from stool samples of humans, dogs, and cats. Molecular analyses were performed on 59 samples that tested positive for G. duodenalis on coproparasitological examinations. After extraction, the samples were first tested by nested polymerase chain reaction (n-PCR) analysis of the SSU-rRNA gene, and for the samples that were positive, the β-giardin, TPI, and GDH genes were analyzed. The amplicons obtained in the n-PCR of the β-giardin gene were subjected to PCR-restriction length polymorphism (RFLP) analysis and subsequent digestion with the enzyme HaeIII to differentiate the assemblages. Seven (11.8 %), 34 (57.7 %), and 18 (30.5 %) out of 59 samples were from humans, dogs, and cats, respectively. Nested-PCR results showed that 49.2 % (29/59) of samples were positive for the SSU-rRNA gene, with 42.9 % (3/7) of humans, 55.9 % (19/34) of dogs, and 38.9 % (7/18) of catsve. Of the other genes analyzed, β-giardin was amplified most frequently, in 34.5 % (10/29) of samples, followed by GDH in 27.6 % (8/29) of samples, and TPI in 10.3 % (3/29) of samples. Only one sample from a dog showed the amplification of all genes. PCR-RFLP analysis showed assemblage F in a human, dog, and cat samples; and assemblage C and D in dog samples. This is the first description of assemblage F in humans from Brazil and the first description of assemblage F in dogs. Further studies are needed to verify the frequency with which these infections occur, and provide information that will contribute to the molecular epidemiological understanding of giardiasis.

PL02.2.A Microglia-specific disruption of sialic acid-Siglec-9/E interactions. A novel immunotherapy against glioblastoma?

Background

Recently, ‘don’t eat me’-signals like CD47 have emerged as novel innate immune checkpoints, enabling cancer cells to evade clearance by phagocytes such as monocyte-derived macrophages (MdM) or microglia (MG). Here, we aim at defining the role of inhibitory Siglec-9 in human and its mouse homologue Siglec-E in MG-centered immunotherapy against GBM.

Material and Methods

We employed a CT-2A orthotopic GBM mouse model with MG specific (Sall1CreERT2 x Sigleceflox) and whole innate-compartment (Cx3cr1CreERT2 x Sigleceflox) spatio-temporal deletion of Siglece. We applied multi-color flow cytometry, transcriptomics and proteomics analysis to decipher the immune response upon Siglece knockout.

Results

TCGA RNA-sequencing data revealed a significant correlation between high expression of immunoinhibitory SIGLEC9 and poor survival in GBM patients (log-rank p = 0.02). Siglec-E blockade increased murine MG mediated GBM cell in vitro phagocytosis (normalized phagocytosis of 1.00 in isotype vs. 1.76 in anti-Siglec-E antibody, p < 0.001). In the MG specific spatio-temporal deletion of Siglece (Sall1CreERT2 xSigleceflox), we observed high MG-proliferation upon Siglec-E knockout (Ki-67+ MG 14.8% in Cre- vs. 34.9% in Cre+, p < 0.0001) accompanied by an enhanced microglial GBM-cell uptake (5.6% in Cre- vs. 12.3% in Cre+, p < 0.001). By extending the Siglece knockout to the MdM compartment in our glioma mouse model (Cx3cr1CreERT2 x Sigleceflox) we observed a significantly prolonged survival in the Cx3cr1Cre+ population (21d in Cre- vs. 27d post-tumor injection in Cre+, p = 0.018), which could be further promoted by combining Siglece knockout with CD47 blockade (30d post-tumor injection in Cre+ + anti-CD47). Unbiased proteomics analysis revealed increased antigen processing and presentation capabilities of Siglece knockout MdMs which was confirmed by ex-vivo OT-1 cross-presentation assays. This bridging of innate and adaptive responses with increased T cell priming upon MdM Siglece knockout was further promoted by addition of anti-PD1 antibody to the combined Siglece knockout and anti-CD47 treatment arm. Animals harboring CT-2A tumors, exhibited a sustained survival benefit under the triple therapy, with 23% of animals experiencing long-term remission, even after tumor re-challenge into the contra-lateral hemisphere. By genetically targeting sialic acids, the ligand for Siglec receptors, on CT-2A cells (GNE-KO), we observed a strong innate and adaptive immune response with increased GBM-cell phagocytosis by MG and MdMs and less exhausted tumor-infiltrating CD8+ T-cells (14.8% in WT vs. 5.9% in GNE-KO, p = 0.003).

Conclusion

These data identify the sialic-acid-Siglec-E pathway as an anti-phagocytic signal in a pre-clinical GBM model, and demonstrate its therapeutic potential in GBM immunotherapy.

OS05.4.A Single-cell characterization of human GBM reveals regional differences in tumor-infiltrating leukocyte activation

Background

Clinical trials of systemic T cell checkpoint blockade in GBM patients showed only disappointing results. This may be attributed in part to the immunosuppressive components of the GBM immune tumor microenvironment (iTME). Therefore, major efforts have been undertaken to describe the GBM iTME on a single cell level. However, human data on the composition of the iTME in different tumor regions (contrast enhancing tumor center versus peripheral infiltration zone) remain scarce.

Material and Methods

Here, we performed high-depth single-cell RNA sequencing (scRNA-seq) on patient-matched biopsies from tumor center and the peripheral infiltration zone of five primary GBM patients. Additionally, peripheral blood mononuclear cells (PBMC) of the same patients were included in the analysis to explore the transcriptional changes occurring during tumor infiltration of circulating immune cells. Main findings of the transcriptional analysis were confirmed by flow cytometry.

Results

Through analysis of > 45’000 cells, we revealed a distinct regional transcriptional profile of microglia (MG) and monocyte-derived macrophages (MdM), a non-reactive/exhausted MG subcluster in the GBM iTME and an impaired interferon-response signature in the tumor-peripheral cytotoxic cell compartment. Comparing CD8+ T cells from the tumor periphery to PBMC-derived CD8+ T cells of the same patient revealed CX3CR1high and CX3CR1int CD8+ T cells with effector and memory phenotype, respectively, enriched in the PBMC but lacking in the tumor periphery. Tumor peripheral CD8+ T cells shared features with tissue-resident memory CD8+ T cells with exhausted effector functions.

Conclusion

Our analysis provides a large-scale dissection of GBM-associated cell types complemented by patient-matched PBMCs, serving as a high dimensional reference map of the human GBM iTME.

P06.03.A Combination of EGFRvIII CAR T cell therapy and paracrine GAM modulation for the treatment of GBM

Background

The glioblastoma (GBM) immune microenvironment mainly consists of protumoral glioma-associated microglia and macrophages (GAMs). Previously, we showed that blockade of the don't-eat-me signal CD47, overexpressed by GBM cells, rescued GAMs' phagocytic function in mice. However, CD47 blockade monotherapy has been ineffective in treating human solid tumors to date. Thus, we propose a combinatorial approach of local chimeric antigen receptor (CAR) T cell therapy with paracrine GAM modulation for a synergistic elimination of GBM.

Material and Methods

We lentivirally transduced healthy donor human T cells to generate humanized EGFRvIII-directed CAR T that constitutively secrete a SIRPγ-related protein (SGRP) with high affinity to CD47. Killing assays were performed with endogenous EGFRvIII-expressing BS153 or EGFRvIII-overexpressed U251 GBM cells and assessed by Incucyte time-lapse imaging analysis. CAR T cell activation was confirmed by flow cytometry (FC) and IFNγ was detected from co-culture supernatants or mouse plasma by ELISA. The CAR T cell secretome was analyzed by liquid chromatography-mass spectrometry (LC-MS) to confirm the secretion of SGRP. NSG mice were orthotopically implanted with either EGFRvIII+ BS153 or U251 cells and treated intratumorally with one or two CAR T cell infusions.

Results

EGFRvIII and EGFRvIII-SGRP CAR T proliferated and killed tumor cells in vitro in a dose-dependent manner within 72h with complete cytotoxicity at E:T 1:1 compared to CD19 CAR T. CAR T cells specifically co-expressed CD25 and CD107a and secreted IFNγ in the presence of tumor antigen (24h CD25/CD107a co-expression: EGFRvIII=59.3±3.00%, EGFRvIII-SGRP=52.6±1.42%, CD19=0.1±0.07%; 24h IFNγ secretion: EGFRvIII=173.6±2.50%, EGFRvIII-SGRP=113.8±6.42%, CD19=4.5±1.49%). Differential expression analysis of the CAR T cell secretome identified SGRP in EGFRvIII-SGRP CAR T supernatants (-Log10qValue/Log2fold-change=13.72/6.62). Consistent with studies of systemic EGFRvIII CAR T cell therapy, our data suggest that intratumoral EGFRvIII CAR T were insufficient to eliminate BS153 tumors with endogenous EGFRvIII (Overall survival; EGFRvIII: 20%, CD19: 0%, n=5/group).

Conclusion

Here, we show that EGFRvIII CAR T specifically targeted and killed EGFRvIII+ GBM cells in vitro, but failed to control tumor growth in vivo without GAM modulation. EGFRvIII-SGRP CAR T secretome analysis identified SGRP from the supernatants of unstimulated monocultures. SGRP impaired the binding of SIRPα-Fc to CD47-upregulated GBM cells in vitro, but did not elicit macrophage-mediated phagocytosis of GBM cells in our current in vitro experimental setup. Future work will focus on the functional characterization of SGRP and on further investigating the additive effect of CAR T cell therapy and GAM modulation using translational in vivo and ex vivo models.

Neospora caninum infection and reproductive problems in dairy cows from Brazil: A case-control study

Neosporosis, an infectious disease caused by the protozoan Neospora caninum, has been associated with economic losses in cattle rearing worldwide. However, previous studies have not presented any evidence regarding the association between serological status of neosporosis and alteration of the reproductive parameters. Thus, this study aimed to determine whether N. caninum is associated with reproductive disorders and to evaluate the possible risk factors of the infection. Blood samples from 202 dairy cows, 51 with a history of reproductive disorders (case group) and 151 without (control group), were collected from different farms in Brazil. Epidemiological questionnaires were conducted with all the farmers. Serum samples were subjected to an indirect fluorescent antibody test to detect antibodies against the parasite. In total, 28.22% (57/202) of the cows were seropositive: 47.06% (24/51) from the case group and 21.85% (33/151) from the control group. By logistic regression, cows aged ≥48 months and cows with history of abortion were 4.8 (95% confidence interval [CI] = 1.91-12.05; p = 0.001) and 2.3 (95% CI = 1.06-5.1; p = 0.034) times more likely to be seropositive, respectively. Furthermore, our results show an association between N. caninum seropositivity and abortion in dairy cows from Brazil with poor management conditions and N. caninum seropositivity risk factors for reproductive disorders.

Prevalence and risk factors of Eimeria spp. natural infection in sheep from northern Paraná, Brazil

The present study aimed to perform an epidemiological and morphological identification of Eimeria infection in sheep in Brazil. Fecal samples from sheep were collected from 20 farms in northern Paraná, Brazil. An epidemiological questionnaire was used to evaluate the risk factors. Fecal samples containing oocysts per gram of feces (OoPG) ≥1000 were subjected to the modified Willis-Mollay method to perform oocyst identification. Sporulated oocysts were observed microscopically for morphological identification. A total of 807 fecal samples were collected. Based on the morphological characteristics of the sporulated oocysts, 10 species of Eimeria were identified, with main species observed: Eimeira ovinoidalis (98.1%), Eimeria crandallis (87.6%), Eimeria parva (79.1%), and Eimeria bakuensis (60.8%). Only 2.6% (7/268) of the sheep were infected with a single species, 4.8% (13/268) contained two different species, and 92.5% (248/268) were infected with three or more species. The analysis of risk factors showed that an intensive rearing, no rotation of pasture, dirt, and slatted floors, and age up to 12 months were associated with infection. This study showed a high prevalence of Eimeria natural infection in sheep from northern Paraná, Brazil. Furthermore, based on the risk factors, good management and hygiene practices must be employed to avoid infection.

Evaluation of quantitative polymerase chain reaction for the detection of Toxoplasma gondii oocysts shed by cats

Felines are definitive hosts of Toxoplasma gondii and can shed oocysts in their feces, contaminating the environment. Sporulated oocysts are highly resistant to the environment and have higher infectivity, which are attributed to many toxoplasmosis outbreaks. The aim of the present study was to evaluate a quantitative polymerase chain reaction (qPCR) technique for the detection of T. gondii oocysts shed by cats. Twelve cats from a previous vaccine experiment were challenged orally with 600 cysts of the TgDoveBr8 strain on day 72. Fecal samples were collected daily using the centrifugal flotation technique, with microscopic examination (Sheather technique) and qPCR for 20 days after the challenge. Cats from all groups shed oocysts in their feces. Five negative cats in the Sheather were positive according to qPCR on the 3rd day post-inoculation (dpi). Oocysts were detected on the 4th dpi using the Sheather; however, there was no statistical difference between the two methods (p=0.1116). In addition, there was no statistically significant difference in oocyst shedding between the groups according to the Sheather technique (p=0.6534) and qPCR (p=0.9670). In conclusion, these results demonstrate that qPCR can be used as an alternative to the Sheather to detect and quantify T. gondii oocysts.

Comparison of serological and molecular techniques to detect Toxoplasma gondii in free-range chickens (Gallus gallus domesticus)

The present study aimed to compare different indirect and direct diagnostic techniques to diagnose Toxoplasma gondii in free-range chickens. Samples of 386 chickens obtained from 24 Paraná properties were used for serological analysis by indirect fluorescent antibody test (IFAT), modified agglutination test (MAT), and enzyme-linked immunosorbent assay (ELISA). Animals positive by IFAT and/or MAT had their tissues submitted to the mouse bioassay, and those who were positive in this technique had their blood, tissues, and acidic pepsin tissue digestion submitted to PCR (conventional, nested, and quantitative-PCR (qPCR)). One hundred and nineteen chickens (30.8 %) were positive in at least one of the serological tests, being 102 (26.4 %) in the IFAT, 64 (16.6 %) in the MAT, and 62 (16.0 %) in the ELISA. The IFAT was used as a gold standard, and the MAT showed higher sensitivity (46.0 %) and specificity (94.0) compared to ELISA (43.5 % and 93.6 %, respectively). Ninety samples of eighteen chickens positive in the mouse bioassay were subjected to PCR, and according to molecular tests, the conventional PCR detected the T. gondii DNA in 30 % (27/90) of the samples, in 38.8 % (35/90) with nested-PCR and 40.0 % (36/90) with real-time. According to molecular analyzes, the sensitivity was higher in ITS1 nested-PCR (69.4 %) and specificity in conventional PCR-529bp (90.7 %), using the qPCR as the gold standard. MAT and ELISA had similarities in concordance analyzes. The IFAT was the serological technique with the highest agreement with the mouse bioassay, and serological tests in parallel showed to be a good screening option for the isolation of T. gondii in chick tissues. The PCR markers effectively detected the parasite DNA, and the heart was the tissue with the highest number of positives samples. The conventional PCR had sensitivity similar to nested-PCR and qPCR and could be a cheaper alternative to diagnose T. gondii infection in chicken tissues.

First study of Cryptosporidium spp. occurrence in eared doves (Zenaida auriculata)

Cryptosporidium is a protozoan parasite with a wide range of hosts, including humans. However, only a few Cryptosporidium species have been described in birds (C. meleagridis, C. baileyi, C. galli and C. avium). The aim of this study was to investigate the occurrence of Cryptosporidium spp. in feces of eared doves (Zenaida auriculata), followed by molecular characterization of the parasite. A total of 196 animals of both sexes were trap-captured; the animals were culled and the intestinal contents were collected for DNA extraction. After extraction, a nested-PCR (nPCR), which amplifies a fragment of the 18S rRNA gene of Cryptosporidium spp., was performed. The amplicons obtained were purified and sequenced. PCR analysis revealed that 30 animals (15.3%) were positive for Cryptosporidium spp. There was no significant sex-dependent enrichment of Cryptosporidium occurrence (p > 0.05). Only 15 out of the 30 positive samples were successfully sequenced and their species determined, of which, 13 (86.7%) and 2 (13.3%) were C. meleagridis and C. galli, respectively. Herein, we present for the first time a molecular characterization of Cryptosporidium from feces of eared doves (Z. auriculata) and propose that these birds are a potential source of C. meleagridis infection in humans.

Prevalence of Eimeria spp. in calves from dairy farms in northern Paraná state, Brazil

Abstract Bovine coccidiosis is a disease of major importance in cattle herds across the world. The disorder mainly affects young calves, and E. bovis and E. zuernii are considered the most pathogenic species of the genus, however, E. alabamensis have been described in grazing calves. In this study, the prevalence of Eimeria spp. was evaluated in calves on dairy farms in the northern region of the state of Paraná, Brazil. Four hundred calves on 44 dairy farms were tested for the presence of coccidian oocysts. The positives were re-examined and the oocysts were morphometrically analyzed for species identification. All the farms were contaminated and 205 animals (51.25%) presented Eimeria spp. oocysts. Among these, 146 animals (71.22%) were co-infected by two or more species of coccidia. Ten species of Eimeria were identified: E. bovis (in 30.25% of the positive samples), E. alabamensis (26.75%), E. zuernii (22.00%), E. ellipsoidalis (18.50%), E. auburnensis (13.75%), E. canadensis (8.00%), E. cylindrica (7.25%), E. subspherica (5.00%), E. bukidnonensis (3.00%) and E. brasiliensis (0.75%). This study demonstrates the high prevalence of Eimeria spp. in the northern region of Paraná, Brazil, and detection for the first time in our region the pathogenic species E. alabamensis.

Survey of Neospora caninum in eared doves (Zenaida auriculata) in Southern Brazil

Neosporosis is an infectious disease caused by Neospora caninum, a protozoan parasite that has worldwide distribution and is responsible for enormous economic losses in cattle. Birds are considered a good bioindicator of environmental contamination, since they feed on the ground, being exposed to N. caninum oocysts. The aim of this study was to determine the occurrence of antibodies against N. caninum and to verify the presence of parasite DNA in brain from free-ranging eared doves (Zenaida auriculata) from Southern Brazil. For this purpose, blood and brain samples were collected from 249 doves for ELISA and PCR analysis respectively. The prevalence of N. caninum antibodies in doves was 31.72% (79/249) and detection of parasite DNA was not observed in none of birds. This is the first report of antibodies against N. caninum in doves Z. auriculata, what show us that these birds had previously contact with the parasite but since no N. caninum DNA was detected, more studies should be performed to elucidate the real importance of doves in the epidemiologic cycle of the N. caninum.

Risk factors associated with resistance to HIV testing among transwomen in Brazil

Transwomen are a high-risk population for HIV/AIDS worldwide. However, many transwomen do not test for HIV. This study aimed to identify factors associated with resistance to HIV testing among transwomen in Fortaleza/CE. A cross-sectional study was conducted between August and December 2008 with a sample of 304 transwomen recruited through respondent-driven sampling. Data analysis utilized Respondent-Driven Sampling Analysis Tool and SPSS 11.0. Univariate, bivariate, and multivariate analyses examined risk factors associated with resistance to HIV testing. Less than 18 years of age (OR = 4.221; CI = 2.419-7.364), sexual debut before 10 years of age (OR = 6.760; CI = 2.996-15.256), using illegal drugs during sex (OR = 2.384; CI = 1.310-4.339), experience of discrimination (OR = 3.962; CI = 1.540-10.195) and a belief that the test results were not confidential (OR = 3.763; CI = 2.118-6.688) are independently associated with resistance to testing. Intersectoral and targeted strategies aimed at encouraging the adoption of safer sexual behaviors and testing for HIV among transwomen are required.

Self-reported sexual behaviour and HIV risk taking among men who have sex with men in Fortaleza, Brazil

OBJECTIVES

To describe and identify sociodemographic and behavioural characteristics and other factors related to high-risk behaviour for HIV infection of men who have sex with men (MSM) living in Fortaleza, Brazil.

METHODS

A survey was carried out among 400 MSM aged 14-65 years and recruited through the snowball technique or in gay-identified venues. A semi-structured questionnaire was conducted among them. Logistic regression analysis was used to model the dichotomous outcome (high risk or low risk).

RESULTS

Forty-four per cent of the participants reported engaging in high-risk sexual behaviour in the previous year. MSM less informed about AIDS, reporting more sexual partners, reporting at least one female partner in the previous year, having anal sex as the favourite way to have sex, and having great enjoyment of unprotected anal sex were more likely to be engaged in risky behaviour. Twenty-three per cent of participants reported at least one sexual contact with women during the previous year. Two-thirds of men who had unprotected sex with their female partners also had unprotected anal sex with their male partners.

CONCLUSIONS

A large proportion of MSM in Fortaleza still remain at elevated risk for contracting HIV infection. The factors predictive of high-risk sexual behaviour are significant in spreading HIV infection among the MSM population and also among their female partners. The lifestyles of these men are different to those of men from other parts of Brazil or outside the country. Preventive interventions need to be culturally and socially specific in order to be effective.