Pasteur Institute of Iran

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  Introduction : Toxoplasmosis is a parasitic infection caused by the protozoan Toxoplasma gondii it leads to serious medical problems in congenitally-infected and immunocompromised individuals, while it is quite harmless in immunocompetent individuals. Toxoplasma tissue cyst matrix protein (MAG1) induces early humoral and cell-mediated immune responses. Previous studies suggested recombinant MAG1 as a promising antigen for serodiagnosis of Toxoplasma infection. A DNA fragment encoding mag1, comprising amino acids 50 to 207, was amplified from T . gondii RH strain and cloned in prokaryotic expression plasmid pET-15b(+). The cloned DNA fragment was sequenced and showed 100% similarity with the published sequences available in GenBank Database. Recombinant MAG1 was expressed in Escherichia coli, and was highly purified in a single step by immobilized metal ion affinity chromatography. In Western blot analysis, purified protein showed a much stronger reactivity with sera from patients with acute Toxoplasma infection, compared to those with chronic infection. MAG1 protein, in combination with other acute-phase markers might be useful in discriminating acute/reactivated Toxoplasma infections from chronic forms. J Med Microbiol Infec Dis, 2014, 1 (2): 5 pages.

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Introduction: Toxoplasma gondii is one of the most important foodborne pathogens. Toxoplasmosis causes abortion and neonatal loss in livestock and imposes significant losses to farming industry. Prevalence of T. gondii in sheep and goats was investigated in three adjacent geographical areas within Gilan province in north of Iran. Methods: Serum samples were collected from 247 sheep and 155 goats in three counties Roudsar with humid subtropical climate and average annual precipitation (AAP) of 1400 mm, Masal with sub-humid climate and AAP of 700 mm, and Roudbar with cold semi-arid steppe climate and AAP of 400 mm. The samples were tested for Toxoplasma antibodies by using Sabin- Feldman Dye Test. Results: The overall prevalence in sheep was significantly higher than goats (P<0.001). Moreover, the prevalence in sheep was greatly increased with AAP (P<0.001) the prevalence in sheep was 62.2% in Roudsar, 39.3% in Masal and 15% in Roudbar. Conclusion: Sheep is the most common source of meat consumed in Iran, as well as many parts of the world, and presents the most danger in foodborne transmission of T. gondii to humans. Intensive farm management resulted in decreased prevalence of Toxoplasma in poultries and pigs while sheep are raised in small flocks in Iran, as many other developing countries, and extensively exposed to oocysts shed by cats. The information obtained here could have important implications for prevention of T. gondii infection in humans as well as reducing the rate of infection, and consequent abortion and neonatal loss in sheep and goats. 

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Introduction: Livestock is a known source of Crimean-Congo Hemorrhagic Fever (CCHF) virus infection in humans. Although CCHF is endemic in Iran, limited human cases of CCHF are reported from northwest of Iran. Considering the lack of complete and updated information on the status and distribution of CCHF infection among domestic animals in Ardabil province, this study was conducted to investigate the CCHF status among sheep in this area. Methods: In this study, 256 sera from sheep were collected from various geographical regions of Ardabil in 2011, and tested for specific CCHF IgG antibodies by ELISA. Results: The Seroprevalence of CCHF in this area was 27.34%. The seropositivity rate of CCHF in northern regions (36.36%) was higher than in central (26.27%) and southern (20%) regions. The highest and lowest seropositivity of CCHF were seen in Parsabad (45.57%) and Khalkhal counties (17.78%), respectively. Conclusions: In this study, a relatively high seroprevalence of CCHF was seen among livestock in the province. Therefore, health care system should increase its surveillance for the detection of CCHF patients. Molecular studies to compare the virus strains circulating in this province and those in the eastern regions of the country can shed more light on the epidemiology of the disease.

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Rabies is a zoonotic viral disease. The causative agent is a negative-sense RNA genome virus of the genus Lyssavirus (Family: Rhabdoviridae). The disease, commonly transmitted by rabid dogs, is the cause of mortality of over 59000 humans worldwide annually. This disease can be prevented before the development of symptoms through proper vaccination even after exposure. Hence, improvement of the vaccination schedule in the countries where rabies is endemic is essential. In addition to the type of vaccine, injection routes also contribute to enhanced immune responses and increased potency of the vaccines. The vaccines approved by the World Health Organization (WHO) include cell culture and embryonated egg-based rabies vaccines (CCEEVs). In order to develop a vaccine against rabies, it is necessary to use an appropriate delivery system to promote a proper antigen-specific immune response. Different routes of injection such as intradermal (ID), intramuscular (IM) or subcutaneous (SC) are practiced, with controversies over their suitability. In this article, we discuss the immunological aspects of rabies vaccination by comparing ID and IM delivery systems.

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Introduction: This study aimed to evaluate rSAG1-PLGA efficacy as a particulate vaccine in conferring protection against Toxoplasma gondii infection in C57BL/6 mice. In light of our previous studies, we studied mice genotype role in eliciting immune responses by rSAG1-PLGA nanoparticles in this study. Methods: Poly (DL-lactide-co-glycolide) (PLGA) nanoparticles loaded by rSAG1 as a subunit vaccine were prepared, and C57BL/6 mice were subcutaneously immunized twice at a 3-week interval by rSAG1-PLGA, soluble rSAG1, blank PLGA, and one group kept unvaccinated. The characteristics of PLGA nanoparticles, the amounts of produced IFN-γ, IL-10, specific anti-ToxoplasmaIgGs, and the conferred protection against infection by T. gondii RH tachyzoite were assessed. Results: rSAG1-PLGA nanoparticles shared a z-average of about 450nm with negative Zeta potential. Compared with the negative control group, the mice vaccinated with rSAG1-PLGA nanoparticles produced significantly higher amounts of IFN-γ, specific anti-T. gondii IgG antibodies and higher titer of IgG2a, which resulted in longer survival times. Conclusion: The efficiency of rSAG1-PLGA nanoparticles in inducing humoral and cellular responses and consequently partial protection against acute toxoplasmosis in C57BL/6 was confirmed.

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Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a positive-sense single-strand RNA virus belonging to the Coronaviridae family, responsible for coronavirus infectious disease 2019 (COVID-19) with the rapid transmission. This study aimed to characterize and compare SARS-CoV-2 and SARS-CoV major viral proteins and predict antigen proteasomal cleavage patterns, MHC class I processing and presentation, and B T-cell and anti-inflammatory epitopes. Methods: The amino acid sequences of spike surface (S) glycoprotein, membrane (M) glycoprotein, envelop (E) protein, and nucleocapsid (N) phosphoprotein was obtained from NCBI. The sequences were aligned by MEGA 7.0 and modeled by SWISS-MODEL. The proteasomal cleavage pattern, MHC class I processing, and T-cell epitopes were predicted via IEDB analysis and EPISOFT. The B-cell epitopes were predicted by BepiPred 2.0. Also, the prediction of anti-inflammatory epitopes was performed by AntiInflam. Results: Two major antigen proteins, S glycoprotein and M glycoprotein of SARS-CoV-2, respectively, showed 26.57% and 20.59% less efficiency in proteasomal cleavage and presentation to MHC class I, comparing SARS-CoV. There were fewer B-cell predicted epitopes in SARS-CoV-2, comparing SARS-CoV. The anti-inflammatory properties of SARS-CoV-2 S glycoprotein and N protein were higher than SARS-CoV. Conclusion: It seems that the evolution of SARS-CoV-2 is on the way to reducing antigen-presenting to MHC class I and escaping cellular immunity. Moreover, the predicted hotspot epitopes potentially can be used to induce adaptive cellular immunity against SARS-CoV-2. Besides, SARS-CoV-2 appears to be less immunopathogenic than SARS-CoV due to its higher anti-inflammatory proteins.

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Introduction: Colorectal cancer (CRC) remains a significant global health challenge. Specific strains of Escherichia coli elaborating virulence factors, including cyclomodulins and colibactin, have been increasingly implicated in CRC pathogenesis. This study aimed to determine the prevalence of genes encoding these toxins, namely cnf1, cdtB-I, and clbB, alongside genes associated with biofilm formation, csgA and flu, in clinical E. coli isolates from patients diagnosed with CRC or precancerous lesions. Methods: A total of 44 E. coli isolates were obtained from colorectal tissue biopsies of patients diagnosed with CRC or precancerous polyps, and from healthy controls. PCR was employed to screen for the presence of the toxin-encoding genes cnf1, cdtB-I, and clbB, as well as the biofilm-associated genes csgA and flu. Biofilm formation was assessed quantitatively utilizing a standard microtiter plate assay. Results: The toxin-encoding genes cnf1 and cdtB-I were each detected in 14 isolates (31.8%) across all study groups (CRC, polyp, and healthy controls). In contrast, the clbB gene was identified in 5 isolates (11.4%), exclusively within the polyp and healthy control groups. The biofilm-associated genes csgA and flu exhibited the highest prevalence, being detected in 41 (93.2%) and 22 (50.0%) isolates, respectively, across all groups. Notably, none of the tested isolates demonstrated biofilm formation capability under the experimental conditions employed. Conclusions: This study demonstrated the presence of the cdtB-I gene in E. coli isolates from both early-stage CRC (stages I and II), with a notably higher prevalence in stage I. Furthermore, cdtB-I was also detected in precancerous polyps classified as both high-grade dysplasia (HGD) and low-grade dysplasia (LGD). Intriguingly, the clbB gene was conspicuously absent from all CRC isolates of stages I and II. These findings suggest a potential role for cdtB-I in the early stages of CRC development, warranting further research to elucidate its precise impact on the progression of CRC. The presence of these virulence-associated genes, without significant differences across groups, underscores the complexity of E. coli's involvement in colorectal carcinogenesis.