Experimental Infection Of Mice Research Articles

Prevalence and Morphological Investigation of Parasitic Infection in Freshwater Fish (Nile Tilapia) from Upper Egypt

Fish are a source of high-quality protein with low cholesterol, but they are susceptible to parasitic infections, which have a significant impact on aquaculture, in addition to their zoonotic potential. The present study estimated parasitic infections and evaluated the diversity of zoonotic parasites in freshwater Nile tilapia (Oreochromis niloticus) in Assiut Governorate, Upper Egypt. A total of 300 samples were randomly collected from the Assiut Governorate. These fish were examined for both ectoparasites and endoparasites, followed by the experimental infection of mice with encysted metacercariae (EMC) for the retrieval of the adult worms. The overall prevalence of the variable parasites was 82% (246 of 300). Both ecto- and endoparasites were detected in 41% (123 of 300) of the examined fish. The identified ectoparasites were Gyrodactylus, Dactylogrus, Cichlidogyrus, Trichodina and Icthyophthirius multifiliis, in 5%, 4%, 22%, 6% and 4% of the fish, respectively. The endoparasites were trematodes (Orientocreadium batrachoides 3%), nematodes (Contracaecum. 2%), acanthocephala (Acanthosentis tilapiae 25%) and protozoa that included Isospora and Eimeria spp., in 1% and 8% of fish, respectively. Myxobolus was detected in 2% of the examined fish. The overall prevalence of encysted metacercariae (EMC) was 95% (285 of 300), while infection with macroscopic EMC had a prevalence of 37% and microscopic EMC had a prevalence of 58%. The adult worms recovered from the experimental infections were Prohemistomum vivax and Mesostephanus spp., which belong to the family Cyathocotylidae. Collectively, these findings reflect the relatively high occurrence of parasites among the studied fish, confirming the necessity of strict measures to control infection.

Immune response study of salmonella mbandaka isolated from human in (balb/c) mice

The bases of this study is to evaluate the immune response to experimental infection of (BALB/c) mice by Salmonella Mbandaka . The experiment was carried out on one hundred mice of both genders with age range (6 – 8) weeks old, the mice were divided randomly into two groups (group A: includes 50 mice were given orally on infective dose (1.3×107C.F.U\ml) ,group B: includes 50 mice which inoculated orally with 1 ml of phosphate buffer saline (pH=7.2) and considers as control group).The study has showed that the experimentally infected mice (group A) are able to induce humoral and cellular immune response . The humoral immune response was detected by Enzyme-linked Immunosorbent Assay post induced infection in mice with infected dose. Maximum titers of ( IgG ) antibodies reached of (211.13) at four weeks , slight reduction at six weeks , reached a mean (179.41 ± 29.47), while in the eight weeks after infection, there was a reduction in the(IgG) titers to reach a mean (58.83 ± 34.56). While group B showed the normal range of IgG titer (20.22 ± 1.11 , 20.79 ±1.71 , 19.81 ± 0.88, 20.22 ± 1.11 , 20.97 ± 0.57 ) at zero time , 2 ,4 , 6 ,8 weeks respectively . The cellular immune response was detected by using the skin test mean thickness of the right foot pad was (2.85±0.06) millimeter after 24 hours, then increased to reach (3.69 ±0.07) mm after 48 hours , then declined to reach (2.71±0.09)mm after 72 hours in mice infected by infective dose. This study concluded that Salmonella Mbandaka infection of the host was able to induce both humoral and cellular immune responses, and these responses are dose dependent.

Validation of Multiplex PCR and Serology Detecting Helicobacter Species in Mice

High-throughput multiplexed assays are needed to simplify detection of Helicobacter species in experimental infection and routine health monitoring of laboratory mice. Therefore, fluorescent bead-based hybridization assays for Helicobacter sp. DNA and serology were developed. Multiplex PCR amplicons (H. hepaticus, H. bilis, H. typhlonius, H. pylori, H. muridarum, H. pullorum, H. cinaedi, H. heilmanii, C. jejuni) and antibodies against H. pylori, H. hepaticus, H. bilis were assessed in naturally and experimentally infected mice, and results compared to conventional PCR. Species-specific and sensitive detection of seven Helicobacter spp. <100 copies/PCR, and of two species <1000 copies/PCR was successfully established in the Helicobacter multiplex DNA finder. The novel assay was highly comparable with conventional PCR (kappa = 0.98, 95%CI: 0.94-1.00). Antibody detection of H. hepaticus and H. bilis showed low sensitivity (71% and 62%, respectively) and cross-reactivity in H. typhlonius-infected mice. Infection experiments showed that antibodies develop earliest two weeks after DNA detection in feces. In conclusion, detection of Helicobacter antibodies showed low sensitivity depending on the timing relative to infection. However, Helicobacter multiplex DNA finder is a sensitive and specific high-throughput assay applicable in routine health monitoring for laboratory animals.

The DmeRF System Is Involved in Maintaining Cobalt Homeostasis in Vibrio parahaemolyticus

Although cobalt (Co) is indispensable for life, it is toxic to cells when accumulated in excess. The DmeRF system is a well-characterized metal-response system that contributes to Co and nickel resistance in certain bacterial species. The Vibrio parahaemolyticus RIMD 2210633 genome also harbors a dmeRF operon that encodes a multiple antibiotic resistance regulator family transcriptional regulator and a cation diffusion facilitator family protein. Quantitative real-time PCR, growth curves analysis, inductively coupled plasma-mass spectrometry, β-galactosidase activity assays, electrophoretic mobility shift assays, and a mouse infection experiment were performed to characterize the function of the DmeRF system in V. parahaemolyticus. Zinc, copper, and Co significantly increase dmeF expression, with Co inducing the greatest increase. DmeF promotes V. parahaemolyticus growth under high-Co conditions. Additionally, increased accumulation of cellular Co in the ΔdmeF mutant indicates that DmeF is potentially involved in Co efflux. Moreover, DmeR represses the dmeRF operon by binding directly to its promoter in the absence of Co. Finally, the DmeRF system was not required for V. parahaemolyticus virulence in mice. Collectively, our data indicate that the DmeRF system is involved in maintaining Co homeostasis in V. parahaemolyticus and DmeR functioning as a repressor of the operon.

Effect of B-NIPOx in Experimental Trypanosoma cruzi Infection in Mice.

Chagas disease is caused by Trypanosoma cruzi and represents a major public health problem, which is endemic in Latin America and emerging in the rest of the world. The two drugs that are currently available for its treatment, Benznidazole and Nifurtimox, are partially effective in the chronic phase of the disease. In this study, we designed and synthesized the benzyl ester of N-isopropyl oxamic acid (B-NIPOx), which is a non-polar molecule that crosses cell membranes. B-NIPOx is cleaved inside the parasite by carboxylesterases, releasing benzyl alcohol (a molecule with antimicrobial activity), and NIPOx, which is an inhibitor of α-hydroxy acid dehydrogenase isozyme II (HADH-II), a key enzyme in T. cruzi metabolism. We evaluated B-NIPOx cytotoxicity, its toxicity in mice, and its inhibitory activity on purified HADH-II and on T. cruzi homogenates. We then evaluated the trypanocidal activity of B-NIPOx in vitro and in vivo and its effect in the intestine of T. cruzi-infected mice. We found that B-NIPOx had higher trypanocidal activity on epimastigotes and trypomastigotes than Benznidazole and Nifurtimox, that it was more effective to reduce blood parasitemia and amastigote nests in infected mice, and that, in contrast to the reference drugs, it prevented the development of Chagasic enteropathy.

Pseudomonas aeruginosa utilizes the host-derived polyamine spermidine to facilitate antimicrobial tolerance.

Pseudomonas aeruginosa undergoes diversification during infection of the cystic fibrosis (CF) lung. Understanding these changes requires model systems that capture the complexity of the CF lung environment. We previously identified loss-of-function mutations in the 2-component regulatory system sensor kinase gene pmrB in P. aeruginosa from CF lung infections and from experimental infection of mice. Here, we demonstrate that, while such mutations lowered in vitro minimum inhibitory concentrations for multiple antimicrobial classes, this was not reflected in increased antibiotic susceptibility in vivo. Loss of PmrB impaired aminoarabinose modification of LPS, increasing the negative charge of the outer membrane and promoting uptake of cationic antimicrobials. However, in vivo, this could be offset by increased membrane binding of other positively charged molecules present in lungs. The polyamine spermidine readily coated the surface of PmrB-deficient P. aeruginosa, reducing susceptibility to antibiotics that rely on charge differences to bind the outer membrane and increasing biofilm formation. Spermidine was elevated in lungs during P. aeruginosa infection in mice and during episodes of antimicrobial treatment in people with CF. These findings highlight the need to study antimicrobial resistance under clinically relevant environmental conditions. Microbial mutations carrying fitness costs in vitro may be advantageous during infection, where host resources can be utilized.

Resolution of cryptic species complexes within the genus Metagonimus (Trematoda: Heterophyidae) in Japan, with descriptions of four new species.

A nationwide fish survey was conducted in Japan to detect metacercariae of the genus Metagonimus (Trematoda: Heterophyidae). The metacercariae were subjected to DNA barcoding for molecular species identification. A phylogeny inferred from the sequences of mitochondrial cytochrome c oxidase subunit 1 (cox1) prompted us to recognize three cryptic species complexes (i.e., the M. miyatai complex, the M. takahashii complex, and the M. katsuradai complex). Each complex included one or two undescribed species. For morphological description, adult flukes of each species were raised through the experimental infections of immunosuppressed mice. We propose M. saitoi n. sp., M. kogai n. sp., M. shimazui n. sp., and M. kinoi n. sp., based on their phylogeny, morphology, biogeography, and ecology (host-parasite relationships). The originally described species, M. miyatai, was split into M. miyatai sensu stricto and M. saitoi n. sp. The former is distributed mainly in eastern Japan and uses the sweetfish (Plecoglossus altivelis) and daces (Pseudaspius hakonensis and Ps. sachalinensis) as principal second intermediate hosts, while the latter is in western Japan and its principal fish hosts are the dark chub (Nipponocypris temminckii) and the pale chub (Opsariichthys platypus). The present survey resolves a long-standing controversy on the microtaxonomy of Metagonimus in Japan since the first discovery of Metagonimus yokogawai in 1912, and shows that 10 species of Metagonimus are still distributed in Japan, although human metagonimiasis is almost eradicated.

Experimental Infection of Mice and Ticks with the Human Isolate of Anaplasma phagocytophilum NY-18.

Anaplasma phagocytophilum is the causative agent of tick-borne fever (TBF) and human granulocytic anaplasmosis (HGA) and is currently considered an emerging disease in the USA, Europe, and Asia. The increased prevalence of A. phagocytophilum as a human pathogen requires the detailed characterization of human isolates and the implementation of appropriate animal models. In this study, we demonstrated that the dynamics of infection with the human isolate of A. phagocytophilum NY-18 was variable in three different strains of mice (SCID, C3H/HeN, BALB/c). We further evaluated the ability of Ixodes ricinus to acquire and transmit A. phagocytophilum NY-18 and compared it with Ixodes scapularis. Larvae of both tick species effectively acquired the pathogen while feeding on infected mice. The infection rates then decreased during the development to nymphs. Interestingly, molted I. ricinus nymphs were unable to transmit the pathogen to naïve mice, which contrasted with I. scapularis. The results of our study suggest that I. ricinus is not a competent vector for the American human Anaplasma isolate. Further studies are needed to establish reliable transmission models for I. ricinus and European human isolate(s) of A. phagocytophilum.

A porous cervical mucus plug leads to preterm birth induced by experimental vaginal infection in mice

SummaryDuring gestation, the cervical mucus plug (CMP) acts to seal the cervical canal. Pilot studies in humans have suggested that a porous CMP may increase the risk of uterine infection and preterm birth. We examined the gel-forming content of the mouse vagina and the CMP. We experimentally infected pregnant mice by intravaginal administration of pathogens related to preterm birth in humans. We found that the epithelium in both the vagina and cervical canal of pregnant mice produced the two gel-forming mucins Muc5b and Muc5ac. The CMP was porous in Muc5b-deficient mice for which intravaginal administration of Escherichia coli O 55 led to the activation of an inflammatory response in the uterus and 100% preterm births. The pathogen was found in the mucus plug and uterus. This study shows that Muc5b is essential for the in vivo barrier function and the prevention of uterine infections during gestation.

Exhausted PD-1+ TOX+ CD8+ T Cells Arise Only in Long-Term Experimental Trypanosoma cruzi Infection.

Infection with Trypanosoma cruzi remains the most important neglected zoonosis in Latin America. This infection does not lead to specific symptoms in the acute phase, but chronic infection can result in Chagas disease (CD) with cardiac and/or gastrointestinal manifestations that can lead to death. CD8+ T cells are highly effective and essential to control this infection, but fail to eliminate all parasites. In this study, we show that the CD8+ T cells are modulated by the transient induction of co-inhibitory receptors during acute infection of C57BL/6 mice. Therapeutic intervention strategies with blocking antibodies only had a marginal effect on the elimination of parasite reservoirs. Only long-term chronic infection gave rise to dysfunctional CD8+ T cells, which were characterized by high expression of the inhibitory receptor PD-1 and the co-expression of the transcription factor TOX, which plays a crucial role in the maintenance of the exhausted phenotype. PD-1+ TOX+ CD8+ T cells isolated from the site of infection produced significantly less IFN-γ, TNF-α and Granzyme B than their PD-1- TOX- CD8+ T cell counterparts after T. cruzi-specific stimulation ex vivo. Taken together, we provide evidence that, in the context of experimental infection of mice, the magnitude of the CD8+ T cell response in the acute phase is sufficient for parasite control and cannot be further increased by targeting co-inhibitory receptors. In contrast, persistent long-term chronic infection leads to an increase of exhausted T cells within the tissues of persistence. To our knowledge, this is the first description of infection-induced CD8+ T cells with an exhausted phenotype and reduced cytokine production in muscles of T. cruzi-infected mice.

Immunization with a self-assembling nanoparticle vaccine displaying EBV gH/gL protects humanized mice against lethal viral challenge

SummaryEpstein-Barr virus (EBV) is a cancer-associated pathogen responsible for 165,000 deaths annually. EBV is also the etiological agent of infectious mononucleosis and is linked to multiple sclerosis and rheumatoid arthritis. Thus, an EBV vaccine would have a significant global health impact. EBV is orally transmitted and has tropism for epithelial and B cells. Therefore, a vaccine would need to prevent infection of both in the oral cavity. Passive transfer of monoclonal antibodies against the gH/gL glycoprotein complex prevent experimental EBV infection in humanized mice and rhesus macaques, suggesting that gH/gL is an attractive vaccine candidate. Here, we evaluate the immunogenicity of several gH/gL nanoparticle vaccines. All display superior immunogenicity relative to monomeric gH/gL. A nanoparticle displaying 60 copies of gH/gL elicits antibodies that protect against lethal EBV challenge in humanized mice, whereas antibodies elicited by monomeric gH/gL do not. These data motivate further development of gH/gL nanoparticle vaccines for EBV.

Leishmania (Viannia) braziliensis replicates in mouse bone marrow

Leishmaniasis is a neglected disease caused by species of the protozoan Leishmania. Leishmania (Viannia) braziliensis causes the cutaneous and mucocutaneous forms of the disease. Experimental cutaneous infection of mice is one of the most important preclinical research models of leishmaniasis. Here, we investigated the course of infection in mice inoculated with two reference strains of L. (V.) braziliensis (MHOM/BR/00/BA788 strain [BA] and MHOM/BR/94/H-3227 strain [CE]). Although both parasite strains induced detectable footpad lesions, BA-infected mice developed small non-ulcerated lesions that self-healed, whereas CE-infected mice developed small non-ulcerated lesions that did not regress. The parasites were detected in the footpad lesions, lymph nodes draining the site of inoculation, spleen, and bone marrow of mice infected with BA or CE parasites at 6 and 25 weeks post-inoculation. These data indicate that L (V.) braziliensis-infected mice harbor parasites that spread, even when these animals do not display overt lesions. In addition, this is the first report of the presence of the parasite in the bone marrow of mice inoculated with L. (V.) braziliensis.

The novel LysR-family transcriptional regulator BvtR is involved in the resistance of Brucella abortus to nitrosative stress, detergents and virulence through the genetic regulation of diverse pathways

Brucella is a facultative intracellular bacterium lacking classical virulence factors; its virulence instead depends on its ability to invade and proliferate within host cells. After entering cells, Brucella rapidly modulates the expression of a series of genes involved in metabolism and immune evasion. Here, a novel LysR-family transcriptional regulator, designated Brucellavirulence-related transcriptional regulator (BvtR), was found to be associated with Brucella abortus virulence. We first successfully constructed a BvtR mutant, ΔbvtR, and a complemented strain, ΔbvtR-Com. Subsequently, we performed cell infection experiments, which indicated that the ΔbvtR strain exhibited similar adhesion, invasion and survival within HeLa cells or RAW264.7 macrophages to those of the wild-type strain. In stress resistance tests, the ΔbvtR strain showed enhanced sensitivity to sodium nitroprusside and sodium dodecyl sulfate, but not to hydrogen peroxide, cumene hydroperoxide, polymyxin B and natural serum. Mouse infection experiments indicated that the virulence of the ΔbvtR strain significantly decreased at 4 weeks post-infection. Finally, we analyzed differentially expressed genes regulated by BvtR with RNA-seq, COG classification and KEGG pathway analysis. Nitrogen metabolism, siderophore biosynthesis and oligopeptide transport were found to be the predominantly altered functions, and key metabolic and regulatory networks were delineated in the ΔbvtR mutant. Thus, we identified a novel Brucella virulence-related regulator, BvtR, and demonstrated that BvtR regulation affects Brucella resistance to killing by sodium nitroprusside and sodium dodecyl sulfate. The differentially expressed genes responding to BvtR are involved in diverse functions or pathways in Brucella, thus, suggesting the breadth of BvtR’s regulatory functions. This study provides novel clues regarding Brucella pathogenesis.

Absence of DEATH kinesin is fatal for Leishmania mexicana amastigotes

Kinesins are motor proteins present in organisms from protists to mammals playing important roles in cell division, intracellular organisation and flagellum formation and maintenance. Leishmania mexicana is a protozoan parasite of the order Kinetoplastida causing human cutaneous leishmaniasis. Kinetoplastida genome sequence analyses revealed a large number of kinesins showing sequence and structure homology to eukaryotic kinesins. Here, we investigate the L. mexicana kinesin LmxKIN29 (LmxM.29.0350), also called DEATH kinesin. The activated MAP kinase LmxMPK3, a kinase affecting flagellum length in Leishmania, is able to phosphorylate recombinant full length LmxKIN29 at serine 554. Insect promastigote LmxKIN29 Leishmania null mutants showed no obvious phenotype. However, in mouse infection experiments, the null mutants were unable to cause the disease, whereas LmxKIN29 add-backs and single allele knockouts caused footpad lesions. Localisation using promastigotes expressing GFP-tagged LmxKIN29 revealed that the kinesin is predominantly found in between the nucleus and the flagellar pocket, while in dividing cells the GFP-fusion protein was found at the anterior and posterior ends of the cells indicating a role in cytokinesis. The inability to cause lesions in infected animals and the amino acid sequence divergence from mammalian kinesins suggests that LmxKIN29 is a potential drug target against leishmaniasis.

Determination of streptomycin and doxycycline using LC/MS towards an effective treatment against an experimental Brucella abortus infection in mice

Herein we described a versatile liquid chromatographic method for detection and quantification of the total levels of two antimicrobials [i.e., streptomycin (STM) and doxycycline (DOX)], in mice plasma and selected tissues, with the aid of a single quadrupole as a detection method. The method included a few sample preparation steps, including freeze-drying and in situ triphasic solvent-assisted defatting, precipitation, and extraction, allowing easy and fast tissue sample processing and avoiding analyte loss. Using a murine model, we demonstrated that mass spectrometry detects simultaneously and with high specificity two of the most widespread antimicrobials used against Brucellosis. An accurate [recoveries varied from 75.23 (bone marrow) to 101.33% (liver)] and sensitive (LoD in the ng g−1 range) method to assess STM and DOX in murine tissue, including subtherapeutic and therapeutic doses of the antimicrobials, was achieved. This validated method can be successfully used to monitor the depletion of STM and DOX in several mice tissues and plasma during metabolism after administration.

Insights of OxyR role in mechanisms of host-pathogen interaction of Corynebacterium diphtheriae.

Corynebacterium diphtheriae, the leading causing agent of diphtheria, has been increasingly related to invasive diseases, including sepsis, endocarditis, pneumonia, and osteomyelitis. Oxidative stress defense is required not only for successful growth and survival under environmental conditions but also in the regulation of virulence mechanisms of human pathogenic species, by promoting mucosal colonization, survival, dissemination, and defense against the innate immune system. OxyR, functioning as a negative and/or positive transcriptional regulator, has been included among the major bacterial coordinators of antioxidant response. OxyR was first reported as a repressor of catalase expression in C. diphtheriae. However,the involvement of OxyR in C. diphtheriae pathogenesis remains unclear. Accordingly, this work aimed to investigate the role of OxyR in mechanisms of host-pathogen interaction of C. diphtheriae through the disruption of the OxyR of the diphtheria toxin (DT)-producing C. diphtheriae CDC-E8392 strain. The effects of OxyR gene disruption were analyzed through interaction assays with human epithelial cell lines (HEp-2 and pneumocytes A549) and by the induction of experimental infections in Caenorhabditis elegans nematodes and Swiss Webster mice. The OxyR disruption exerted influence on NO production and mechanism accountable for the expression of the aggregative-adherence pattern (AA) expressed by CDC-E8392 strain on human epithelial HEp-2 cells. Moreover, invasive potential and intracytoplasmic survival within HEp-2 cells, as well as the arthritogenic potential in mice, were found affected by the OxyR disruption. In conclusion, data suggest that OxyR is implicated in mechanisms of host-pathogen interaction of C. diphtheriae.

Schistosoma mansoni infection induces plasmablast and plasma cell death in the bone marrow and accelerates the decline of host vaccine responses.

Schistosomiasis is a potentially lethal parasitic disease that profoundly impacts systemic immune function in chronically infected hosts through mechanisms that remain unknown. Given the immunoregulatory dysregulation experienced in infected individuals, this study examined the impact of chronic schistosomiasis on the sustainability of vaccine-induced immunity in both children living in endemic areas and experimental infections in mice. Data show that chronic Schistosoma mansoni infection impaired the persistence of vaccine specific antibody responses in poliovirus-vaccinated humans and mice. Mechanistically, schistosomiasis primarily fostered plasmablast and plasma cell death in the bone marrow and removal of parasites following praziquantel treatment reversed the observed cell death and partially restored vaccine-induced memory responses associated with increased serum anti-polio antibody responses. Our findings strongly suggest a previously unrecognized mechanism to explain how chronic schistosomiasis interferes with an otherwise effective vaccine regimen and further advocates for therapeutic intervention strategies that reduce schistosomiasis burden in endemic areas prior to vaccination.

A Computational Model of Bacterial Population Dynamics in Gastrointestinal Yersinia enterocolitica Infections in Mice.

Simple SummaryComputational modeling of bacterial infection is an attractive way to simulate infection scenarios. In the long-term, such models could be used to identify factors that make individuals more susceptible to infection, or how interference with bacterial growth influences the course of bacterial infection. This study used different mouse infection models (immunocompetent, lacking a microbiota, and immunodeficient models) to develop a basic mathematical model of a Yersinia enterocolitica gastrointestinal infection. We showed that our model can reflect our findings derived from mouse infections, and we demonstrated how crucial the exact knowledge about parameters influencing the population dynamics is. Still, we think that computational models will be of great value in the future; however, to foster the development of more complex models, we propose the broad implementation of the interdisciplinary training of mathematicians and biologists.The complex interplay of a pathogen with its virulence and fitness factors, the host’s immune response, and the endogenous microbiome determine the course and outcome of gastrointestinal infection. The expansion of a pathogen within the gastrointestinal tract implies an increased risk of developing severe systemic infections, especially in dysbiotic or immunocompromised individuals. We developed a mechanistic computational model that calculates and simulates such scenarios, based on an ordinary differential equation system, to explain the bacterial population dynamics during gastrointestinal infection. For implementing the model and estimating its parameters, oral mouse infection experiments with the enteropathogen, Yersinia enterocolitica (Ye), were carried out. Our model accounts for specific pathogen characteristics and is intended to reflect scenarios where colonization resistance, mediated by the endogenous microbiome, is lacking, or where the immune response is partially impaired. Fitting our data from experimental mouse infections, we can justify our model setup and deduce cues for further model improvement. The model is freely available, in SBML format, from the BioModels Database under the accession number MODEL2002070001.

Investigation of the effect of the calcium channel blocker, verapamil, on the parasite burden, inflammatory response and angiogenesis in experimental Trichinella spiralis infection in mice

Trichinella spiralis larvae have very special characters that make them able to completely transform the function of the affected muscle cells towards a self-serving environment, offering them nourishment and protection via what is known as “nurse cells”. This setting may be affected by drugs that are used for the treatment of co-morbidities and co-infections as calcium channel blockers, which are widely used in clinical practice. In the present study, the effects of verapamil, ivermectin (IVM), and their combined administration on the parasitic burden, immuno-pathology and angiogenesis were investigated during experimental trichinellosis. Estimation of intestinal adult parasitic stages and muscle larvae was done. VEGF gene expression and CD31 immunohistochemical local expression were measured to investigate angiogenesis, in addition to histopathological examination to explore the extent of inflammation. Although verapamil did not have an effect on the adult worm count during the intestinal phase, it induced an anti-inflammatory effect on intestinal pathology. During the muscle phase, it was very effective in reducing the larval count by 93.78%. IVM effectively reduced the worm count by 85.34%, and the muscle larval count by 97.84%, while combined verapamil and IVM administration resulted in a significant reduction in both adult parasites by 69.5% and larval stages by 99%. Both verapamil and IVM and their combination induced a potent decrease in local CD31 protein expression and VEGF gene expression. The important role of calcium and calcium channels during the pathology of trichinellosis, in addition to the pivotal role of calcium on biological processes such as immunity and angiogenesis, make calcium-channel blockers promising candidates for drug repurposing in the management of helminthic infection.

Toxocara canis 30-35 kDa excretory-secretory antigen is an important marker in mice challenged by inocula containing different parasite load levels.

ABSTRACTThe Western-blotting technique was applied to identify antigenic fractions of excretory-secretory Toxocara canis antigen recognized by IgG antibodies throughout an experimental infection in mice challenged by different inocula. Mice were inoculated with 5, 50 and 500 embryonated eggs and serum samples were collected 15, 30, 60, 90 and 120 days post-infection. Serum samples were analyzed using an excretory-secretory Toxocara antigen. Antibodies recognized antigenic fractions from 30 to 90 kDa. The protein fraction of 30-35 kDa was the most frequently recognized regardless of the size of inoculum and the stage of infection represented by the different collection times, but the antigenic recognition was more evident in groups infected with 50 and 500 eggs. This study presents an antigenic panel of the excretory-secretory antigen of T. canis and suggests that the 30-35 kDa antigenic fraction is a promising marker of the infection and should be further explored in future studies on experimental toxocariasis.