Archives of Razi Institute
Volume:75 Issue: 4, Autumn 2020

Toxoplasmosis is a widespread parasitic disease caused by a protozoan parasite Toxoplasma gondii. Currently, nanotechnology has been used for the diagnosis of many infectious diseases. It could be due to the fact that nanoparticles play an important role in accurate and fast diagnosis. The purpose of this study was to design a Nano-enzyme linked immunosorbent assay (Nano-ELISA) kit using excreted/secreted (E/S) antigens to have higher sensitivity and specificity than those reported for the designed enzyme-linked immunosorbent assay (ELISA) kit for the diagnosis of Toxoplasmosis in mice. Firstly, the serum samples were collected from 15 infected mice with T. gondii and 15 healthy ones. Then, E/S antigens were separated from parasite tachyzoites and used for designing an ELISA kit. In addition, the mice sera were evaluated using the designed ELISA kit. Finally, the serum samples were assessed by Nano-ELISA kits designed with E/S antigen and conjugate of gold nanoparticles. The obtained results of the present study showed that the sensitivity and specificity of the designed ELISA kit were reported as 80% and 86.66%, respectively, that both improved to 93.33% in these sera with the designed Nano-ELISA kit. This finding revealed the significant improvement of sensitivity and specificity using gold nanoparticles in designing the ELISA kit. Furthermore, according to the literature, the use of E/S antigens in designing recognizable ELISA kits has been always highlighted considering the presence of numerous antigens in T. gondii. The results of this study revealed that the use of E/S antigens in the preparation of an ELISA kit was very effective. This is very important, especially in the lower titers of antibody requiring a more accurate diagnosis. On the other hand, the Nano-ELISA method designed with E/S antigens can be more sensitive and specific than ELISA for the diagnosis of Toxoplasmosis and can be the basis for further studies in this regard.

The changes in temperature levels can potentially affect the toxins in terms of stability and immunological properties via alteration of their structures. Diphtheria Toxin (DT) is highly considered by scientists since its mechanism of action is similar to those of most bacterial toxins, such as botulinum, tetanus, and anthrax. The protection of conformational B-cell epitopes is critically important in the process of diphtheria vaccine production. This study aimed to evaluate the conformational changes of the DT structure at three different temperature levels (27˚C, 37˚C, and 47˚C) using molecular dynamic simulations. Secondary structures were analyzed in YASARA software. According to the results, significant decreases were observed in percentages of the β-sheets, turns, and the helices of the DT structure at 47˚C in comparison with those at 27˚C and 37˚C. Furthermore, the tertiary structure of the DT was compared at different temperatures using the contact map.  Accordingly, the results showed that the root-mean-square deviation of the DT structure increased upon temperature rising. In addition, amino acids D68, G128, G171, C186, and K534-S535 at 27˚C and 37˚C, as well as amino acids G26, P38, S291, T267, H384, A356, and V518 at 47˚C showed higher root mean square fluctuation values. The finding demonstrated that the stability of the DT structure decreased at high temperature (47˚C). The solvent-accessible surface area diagram showed that the hydrophobicity of the DT structure increased via temperature rising, and the amino acid residues belonging to B-cell epitopes extended through increasing temperature. However, B-cell epitopes belonging to the junction region of chains A and B were only present at 37˚C.  The results of this study are expected to be applicable for determining a suitable temperature level for the production process of the diphtheria vaccine.

Tuberculin skin test, also known as the tuberculin or purified protein derivative (PPD) test, is an extensively applied diagnostic test for the detection of primary infection with Mycobacterium tuberculosis (Mtb). The production of PPD is accompanied by some difficulties that require a series of modifications in the production and purification processes. The present study aimed to determine the facilitation level of the manufacturing process by modifying evaluation methods for the production of PPD tuberculin. Mtb strains were cultured in Lowenstein-Jensen media, and the cultured strains were inoculated into the Dorset-Henley liquid medium by the biphasic medium of potato-Dorset-Henley. After incubation, flasks containing cultured strain were selected for bacterial inactivation, and the optimal gamma radiation dose(s) was determined. Tuberculoproteins were precipitated by ammonium sulfate (AS) and Trichloroacetic acid (TCA). Protein concentration was determined using the Bradford and Kjeldahl protein assay methods. Finally, the lymphocyte transformation test and potency test were performed. Based on the results, the Dorset-Henley liquid medium is suitable for the massive growth of the bacterium. The transferal of Mtb from solid to liquid medium was directly carried out without intermediate culture. It was found that during tuberculoprotein production, heating at 100°C for 3 h would be safe for killing mycobacterium. Furthermore, the simultaneous use of heating and gamma irradiation (8 kGgy) killed all of the mycobacteria, while doses of 1, 1.5, and 7 kGy decreased a significant number of bacterial cells. The results also indicated that the concentration of tuberculoprotein extracted by TCA precipitation method was higher than that obtained by AS precipitation. The tuberculoproteins which were produced by these two methods in the lymphocyte transformation test were not significantly different in terms of potency (P>0.05). Moreover, due to the high volume of produced protein, the protein measurement was more efficiently carried out by the Kjeldahl method, compared to the Bradford method. Finally, the results of the present study demonstrated that in addition to the novel approach of gamma irradiation, optimum methods are efficient and applicable in the production of PPD tuberculin.

Cholera, a life-threatening disease caused by the Gram-negative bacterium Vibrio cholera, remains a concern in developing countries. The present study investigated the immunogenicity and protective immunity of outer membrane vesicles (OMVs) and combination of OMV and killed whole cells (WC) of a local strain isolated from the last outbreak in Iran in addition to reference and local strains of V. cholerae El Tor O1 in comparison to Dukoral vaccine in mice model. The protein content, morphology, and size of extracted OMVs were evaluated by electrophoresis and microscopic analyses, respectively. The serum titers of total immunoglobulin G (IgG), IgG1, IgG2a, and immunoglobulin A (IgA) in addition to secretory IgA and total IgG in different mice groups were determined by enzyme-linked immunosorbent assay (ELISA). In addition, fluid accumulation (FA) assay regarding the resistance to live strain of V. cholerae in ligated ileal loops was carried out to determine immunogenicity by OMV or combination of OMV and WC in comparison to that reported for Dukoral vaccine. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of purified OMVs indicated protein profiles within the range of 34-52 kDa. Furthermore, transmission electron microscopy demonstrated the spherical shaped vesicles of 50-200 nm. The results of ELISA showed significant titers of systemic and mucosal immune anti-OMV IgGs in immunized BALB/c mice with different vaccine regimens. Additionally, a notable increase in the FA ratio was demonstrated in this study. The obtained results of the present study revealed that the WC-OMV combination of local strain can induce a high level of antibody response indicating more protection than OMV or WC separately. Moreover, it can be considered an effective immunogen against V. cholerae.

Toxoplasma gondii is one of the most common foodborne protozoan parasite causing congenital infection, abortion, and stillbirth in humans and animals. The temperate and humid climate is one of the most important factors in the high prevalence of T. gondii. Sheep are among the important sources of meat production in Guilan province, Iran. Therefore, the consumption of raw and half-cooked meat is one of the major risk factors for T. gondii infection. Toxoplasmosis in patients with intact immune systems is usually asymptomatic; however, it but can be life-threatening in patients with a weak immune system (for example, patients with the human immunodeficiency viruses/acquired immunodeficiency syndrome or cancer and transplant recipients). Guilan is divided into three geographical regions of plains with a temperate climatic condition, hillsides with a semi-humid climate, and heights with cold mountainous climate. Climate situations play a role in the prevalence of toxoplasmosis. The present study aimed to investigate the seroprevalence of T. gondii infection among sheep in Guilan province, north of Iran. In the current cross-sectional study, a total of 400 sheep sera samples were tested for the determination of immunoglobulin G (IgG) antibody against T. gondii using the enzyme-linked immunosorbent assay. The samples were divided into different groups according to the geographical location and animal age. T. gondii antibody (i.e., IgG) was detected in 166 sheep (41.5%). The highest frequency of T. gondii infection (72.7%; n=56) was observed for the age group of > 4 years; the difference was statistically significant in this regard (P=0.0001) in comparison to that reported for other groups. In addition, the seroprevalence of T. gondii was significantly higher in the plains (53.9%) than that of the hillsides and heights (P=0.0001). Consequently, the seroprevalence of T. gondii infection in Guilan was high indicating a significant relationship with geographical location and animal age.

Hydatidosis is the most important global parasitic infectious disease both in humans and animals, which can lodge at different organs of the host, such as liver, lung (even heart), and brain which may lead to death. Surgery is the main method for the treatment of hydatidosis. In surgical therapy of hydatidosis, the use of sporicidal agents is very important since these agents inactivate live protoscolices and prevent recurrence of infection. Presently, numerous scolicidal chemical agents have been administrated to inactivate the hydatid cyst contents. Recently, there has been a high tendency among researchers to evaluate and present herbal plants as alternative option due to inexpensiveness, availability, low side effects, and toxicity. This study aimed to evaluate the scolicidal effect of hydro alcoholic Taxus baccata L. extract in vitro for the first time. The scolicidal activities of the extract were tested in concentrations of 50, 100, and 150 mg/ml following 10, 30, and 60 min of incubation, and the experiments were performed in triplicate. Viability of protoscolices was confirmed by 0.1% eosin vital staining. The data were analyzed in SAS software (version 9.4). The results showed that the hydroalcoholic extract of Taxus baccata L. at the concentration of 150 mg/ml led to killing 66.6% of protoscolices at 60 min. according to the results of this investigation, it is recommended to use this plant as a scolicidal plant. The findings of the present study showed that Taxus baccata L. had potent scolicidal effects. However, further studies are required to evaluate the efficacy of Taxus baccata L. in vivo.

The specific changes in antral follicle numbers and wave-like development have remained unrevealed in cyclic ewes fed high-protein, high-energy lupin grain for 6 days during the luteal phase of the estrous cycle (i.e., short-term nutritional flushing). This study was mainly conducted to determine ovarian effects of the 6-day lupin grain feeding in non-prolific Polish Mountain ewes, using transrectal ovarian ultrasonography and abdominal videoendoscopy. Estrus and ovulations were synchronized in 24 ewes with progestin-releasing intravaginal sponges for 12 days during the middle portion of the breeding season (September-October; 50.0458°N, 19.8406°E). Twenty-four ewes were assigned to three equal groups (n=8 each), including the Control group being fed the maintenance diet (i.e., hay-only), Treatment 1 receiving 500 g of lupin grain once a day, and Treatment 2 receiving 250 g of lupin grain twice a day, from days 9-14 of the synchronized estrous cycle (day 0=first ovulation of the interovulatory period studied). No differences were observed in the mean ovulation rate among the three groups of Polish Mountain ewes (P>0.05). Ovarian antral follicles emerging in the penultimate wave of the estrous cycle in Treatment 2 ewes had a longer growth phase (P<0.05) and attained a greater diameter (P<0.05) before ovulation, in comparison to those in the other two groups. A final wave of the interovulatory interval emerged ~1 day earlier in Treatment 2 than in Treatment 1 ewes (P<0.05). Nutritional supplementation with lupin grain increased the number of 3-mm follicles in Treatment 2 ewes (P<0.05). The results of this study indicated that short-term nutritional flushing with lupin grain from mid- to late luteal phase did not consistently enhance ovulatory responses in non-prolific genotypes of ewes. Although the administration of lupins altered the timing of wave emergence, ovulatory follicle diameter, or duration of different stages of the follicular lifespan, it failed to increase the number of ovulatory follicles emerging in the penultimate and final waves of the estrous cycle in non-prolific Polish Mountain sheep.

Multiple sclerosis (MS) is considered a chronic disease of the central nervous system, with a strong neurodegenerative component. The exact mechanism of MS is not clear. However, the therapeutic strategies for controlling MS are based on immune modulation and inflammation control. Regarding this, the present study was conducted to investigate the influence of snake venom on the suppression of the immune system after the induction of experimental autoimmune encephalomyelitis (EAE) in mice. For this purpose, C57BL/6 female mice, divided into three groups, were selected to be induced by EAE. Groups 2 and 3 received flank injection with the emulsion of myelin oligodendrocyte glycoprotein (MOG 35-55), as well as complete Freund adjuvant, followed by the administration of pertussis toxin. Furthermore, the treatment group, as an immune-modulator, received cobra venom (CV) after EAE induction. The mice were then evaluated daily based on clinical symptoms, weight changes (within 26 days), histopathological analysis, and serum levels of interleukin 27 (IL-27) for neurological motor deficits. The clinical signs of MOG-EAE in C57BL/6 mice began 9-14 days post-immunization. Histopathological results also revealed that CV-treated EAE mice, compared to the untreated EAE group, witnessed a significant reduction in the intensity of inflammatory cells in parenchymal sections. Furthermore, the increase of IL-27 levels was significant in the CV-treated group (P=0.001), compared with those in the EAE and control groups. Based on results obtained in the present study, it may be concluded that Naja naja oxiana snake venom is a potential immunomodulatory agent that can be effective in the treatment of MS.

Fowlpox is an economically significant viral disease in poultry, characterized by two forms of clinical signs, including cutaneous and diphtheritic lesions. This infection can have several adverse effects on flock performance, such as a reduction in egg production and growth and an increase in mortality. In winter 2018, an infection suspected to fowlpox was reported from a Hy-line W-36 laying farm in Isfahan province, Iran. The birds were 38 weeks of age and showed obvious diphtheritic signs in mucous membranes with increased mortality and reduced egg production. In total, 20 samples were collected from diphtheritic lesions (Trachea and Esophagus) of infected birds. The Polymerase Chain Reaction method was used to amplify a 578 bp fragment of the poxvirus 4b core protein gene. Phylogenetic relationships of avian poxviruses are usually analyzed using the 4b core protein-coding gene sequences with molecular weights of 75.2 kDa. The major elements had the fowlpox genome, and sequencing was performed for one isolate as representative. The nucleotide sequence result showed that this isolate (FPUT-POX-2018) had a similarity rate of 99.53% with the previous Iranian fowlpox isolate (FPGHPCRLAB.3) sequenced in the GenBank.Moreover, there was a 100% similarity among the current isolate nucleotide sequence, FP/NobilisVarioleW, and FP/FPV-VR250. The derived phylogenetic tree showed that these isolates were clustered in A1 subclades.  Therefore, Iranian isolates of fowlpox virus have remained in the same subclade of phylogenetic classification (subclade A1), and they show high genomic similarity with previous isolates of Iran. Veterinarians and farmers must not underestimate fowlpox. However, they should consider the importance of vaccination against this disease like any other disease care.