A Cryptosporidium parvum vaccine candidate effect on immunohistochemical profiling of CD4+, CD8+, Caspase-3 and NF-κB in mice

BACKGROUND

Cryptosporidium parvum is a protozoan parasite of medical and veterinary importance that causes neonatal diarrhea in many vertebrate hosts. In this study, we evaluated the efficacy of an affinity-purified antigen as a C. parvum vaccine candidate using ileal and liver tissues of experimentally infected neonatal mice by immunohistochemical profiling and immune scoring of CD4+, CD8+, Caspase-3, and nuclear factor kappa B (NF-κB). This vaccine was prepared from the C. parvum oocysts antigen using immune affinity chromatography with cyanogen bromide-activated Sepharose-4B beads.

METHODS

Thirty neonatal mice were divided into three groups (10 mice/group): (1) non-immunized non-infected, (2) non-immunized infected (using gastric tubes with a single dose of 1 × 105 of C. parvum oocysts in 250 µl PBS solution 1 h before a meal) and (3) immunized (twice with 40 µg/kg of purified C. parvum antigen at 2-week intervals and then infected with 1 × 105 C. parvum oocysts simultaneously with the second group). After euthanizing the animals on the 10th day, post-infection, their ileal and liver tissues were collected and prepared for immunohistochemistry (IHC) staining to detect CD4+, CD8+, Caspase-3, and NF-κB levels, which are indicators for T helper cells, cytotoxic T cells, apoptosis, and inflammation, respectively.

RESULTS

The IHC results showed that CD4+, CD8+, Caspase-3, and NF-κB expression varied significantly (P < 0.001) in both organs in all the groups. We also recorded high CD4+ levels and low CD8+ expression in the non-immunized non-infected mice tissues, while the opposite was observed in the non-immunized infected mice tissues. In the immunized infected mice, the CD4+ level was higher than CD8 + in both organs. While the Caspase-3 levels were higher in the ileal tissue of non-immunized infected than immunized infected mice ileal tissues, the reverse was seen in the liver tissues of both groups. Furthermore, NF-κB expression was higher in the liver tissues of non-immunized infected mice than in immunized infected mice tissues. Therefore, the IHC results and immune-scoring program revealed a significant difference (P < 0.001) in the CD4+, CD8+, Caspase-3, and NF-κB expression levels in both ileal and liver tissues of all mice groups, which might be necessary for immunomodulation in these tissues.

CONCLUSIONS

The improvement observed in the immunized infected mice suggests that this vaccine candidate might protect against cryptosporidiosis.

A Novel Designed Sandwich ELISA for the Detection of Echinococcus granulosus Antigen in Camels for Diagnosis of Cystic Echinococcosis

Echinococcus spp. are important cosmopolitan zoonotic parasitic tapeworms that cause a disease called hydatidosis or cystic echinococcosis (CE), which has remarkable economic losses. The objective of our study was to develop a specific IgG polyclonal antigen-based ELISA (Sandwich ELISA; capture ELISA) method for the detection of circulating Echinococcus granulosus (E. granulosus) antigens in camels infected with hydatid cysts before slaughtering and its application in serodiagnosis of CE in animals to assess the positive rate of hydatidosis in camels slaughtered in Giza governorate abattoirs in Egypt. In this study, molecular identification of Echinococcus sp. isolate was performed based on the NADH dehydrogenase subunit 1 (NAD1) gene, revealing the isolate (GenBank: OQ443068.1), which is identical to the G6 E. granulosus sensu lato genotype. The positive rate of hydatid cysts was determined in slaughtered camels' organs (n = 587). The results revealed that hydatid cysts were found in 46.5% (273/587) of the examined camels. Pulmonary echinococcosis was significantly more prevalent in the slaughtered camels (60%, 164/273) than hepatic echinococcosis (39.9%, 109/273), (p = 0.001, Chi Square = 11.081). Cyst fertility rates were higher in hepatic (90.8%, 99/109) than in pulmonary cysts (83.5%, 137/164) and the most viable protoscoleces were recorded from fertile the hepatic cysts (67.85 ± 12.78). In this study, hydatid cyst germinal layer antigen (GlAg) was isolated and used for the immunization of rabbits to raise IgG polyclonal antibodies (anti-Echinococcus GlAb IgG). These IgG polyclonal antibodies were purified by affinity chromatography using a protein A column, then labeled with horseradish peroxidase. Electrophoretic analysis of IgG polyclonal antibodies and crude GlAg was performed in 10% polyacrylamide gels. The SDS-PAGE revealed four bands at molecular weights of 77 kDa, 65 kDa, 55 kDa, and 25 kDa. The Sandwich ELISA was performed to evaluate the sensitivity and specificity and cross-reactivity of the prepared IgG polyclonal antibodies. The circulating hydatid antigen was found in 270 out of the 273 samples with hydatidosis, with a sensitivity of 98.9% (270/273), a specificity of 94.9% (296/312) and a diagnostic efficacy of 96.8%. Regarding the cross reactivity, anti-Echinococcus GlAb IgG showed a low cross-reactivity with Fasciola gigantica infected camel sera (3/8), and Myiasis (Cephalopina titillator larvae; 3/20). No cross-reactivity was recorded with uninfected camel sera (negative sera for E. granulosus), and no cross-reactivity was found with antigens of Eimeria spp., Toxoplasma gondii, Cryptosporidium sp., and Hyalomma dromedarii (ticks' infestation). Then, Sandwich ELISA was conducted again to detect E. granulosus antigen in all the collected camel sera, which resulted in a 48.7% (286/587) positive rate of CE compared to 46.5% (273/587) using a postmortem inspection (PM diagnosis) (p = 0.5, Chi Square = 0.302). In conclusion, the Sandwich ELISA technique introduced in this study appears to be a sufficiently sensitive diagnostic assay for the detection of camels' echinococcosis using anti-Echinococcus GlAb IgG. In addition, it might offer a significant medical and veterinary importance in helping the early detection of hydatidosis, as well as its early treatment.

Evaluation of a vaccine candidate isolated from Cryptosporidium parvum oocyst in mice

Background and Aim

Cryptosporidiosis is a leading cause of diarrheal disease worldwide and is an animal and public health burden. This study aimed to evaluate the protective potential of affinity-purified Cryptosporidium parvum oocyst antigen as a vaccine candidate according to fecal oocyst shedding, humoral and cellular immune responses, histopathological changes, and the number of parasite developmental stages in ileal and hepatic tissues.

Materials and Methods

We isolated oocysts from naturally infected buffalo calves and identified them molecularly as C. parvum isolates (GenBank: ON730707 and ON730708) by targeting the Cryptosporidium oocyst wall protein gene. We propagated the C. parvum oocysts in mice. In addition, we prepared crude antigen from the isolated oocysts by purification using cyanogen bromide-activated Sepharose-4B affinity chromatography coupled with rabbit hyperimmune serum. Then, we divided 81 parasite-free mice into three groups: (1) non-vaccinated non-infected mice, (2) mice orally infected with 1 × 10⁵ C. parvum oocysts on week 4 of the experiment, and (3) mice immunized twice with 40 μg/kg of the purified fraction at 2-week intervals. Then, we challenged the vaccinated group with C. parvum oocysts after 2 weeks, and the positive control group was infected at the same time.

Results

We observed a prolonged prepatent period and decreased oocyst shedding in the vaccinated infected mice compared with the non-vaccinated infected mice (t < 0.001). The vaccinated mice had significantly higher immunoglobulin G levels than those in the other two groups at all examined weeks. In addition, the production of cytokines interferon-gamma, interleukin (IL)-10, IL-12, and IL-15 was activated post-vaccination. After the challenge, all tested cytokines were significantly increased (p < 0.001) in the two infected groups compared with the non-vaccinated non-infected group, with the highest levels in the vaccinated infected group. Vaccinated infected mice exhibited significantly fewer pathological lesions in the ileum and liver than non-vaccinated infected mice, which showed prominent histopathological lesions. Endogenous developmental stages of C. parvum indicated that the ileum was more parasitized than the liver and that vaccination resulted in a lower number of oocysts in ileal and hepatic tissues (p < 0.05).

Conclusion

Our prepared affinity-purified vaccine candidate could be promising in protecting against cryptosporidiosis.

Molecular characterization of some equine vector-borne diseases and associated arthropods in Egypt

Equine vector-borne diseases (EVBDs) are emerging and re-emerging diseases, and most of them are zoonotic. This study aimed to investigate EVBDs in equines and associated arthropods (ticks and flies) from Egypt using molecular analyses, in addition to a preliminary characterization of associated ticks and flies by the matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) and molecular techniques. In this study, 335 blood samples were obtained from equines that appeared to be in good health (320 horses and 15 donkeys) in Cairo and Beni Suef provinces, Egypt. From the same animals, 166 arthropods (105 sucking flies and 61 ticks) were collected. Ticks and flies were preliminary characterized by the MALDI-TOF and molecular tools. Quantitative PCR (qPCR) and standard PCR coupled with sequencing were performed on the DNA of equines, ticks, and flies to screen multiple pathogens. The MALDI-TOF and molecular characterization of arthropods revealed that louse fly (Hippobosca equina) and cattle tick (Rhipicephalus annulatus) infesting equines. Anaplasma platys-like (1.6%), Anaplasma marginale (1.6%), Candidatus Ehrlichia rustica (6.6%), a new Ehrlichia sp. (4.9%), and Borrelia theileri (3.3%) were identified in R. annulatus. Anaplasma sp. and Borrelia sp. DNAs were only detected in H. equina by qPCR. A. marginale, Anaplasma ovis, and Theileria ovis recorded the same low infection rate (0.6%) in donkeys, while horses were found to be infected with Theileria equi and a new Theileria sp. Africa with recorded prevalence rates of 1.2% and 2.7%, respectively. In conclusion, different pathogens were first detected such as A. platys-like, Candidatus E. rustica, and a new Ehrlichia sp. in R. annulatus; A. marginale, A. ovis, and T. ovis in donkeys; and a new Theileria sp. "Africa" in horses.

Cellular immune response and scanning electron microscopy in the evaluation of Moringa leaves aqueous extract effect on Cryptosporidium parvum in buffalo intestinal tissue explants

Cryptosporidium is an apicomplexan parasite of human and animals and is considered as an important co-factor in neonatal diarrhea. In this study, an explant culture was used as an in vitro model of buffalo intestine to evaluate the effect of Moringa leaves extract on Cryptosporidium parvum (C. parvum) oocysts using light and scanning electron microscopy and measuring IFN-γ, IL-12 and IL-14 in the culture supernatants. C. parvum oocysts were collected from naturally-infected calf feces, isolated, excysted and then co-inoculated with ileal tissue explants culture medium. The prepared Moringa leaves extract was then introduced to the infected tissues in the concentrations of 100 mg/ml and 300 mg/ml. After 24 h, tissues were collected and processed for light and scanning electron microscopy. Also, culture supernatants were collected for cytokines measurement. C. parvum parasitophorous vacuoles were found attached to the surface of tissue in Cryptosporidium-infected ileal tissue explants. High magnification imaging of ileal tissue explants using scanning electron microscopy showed that Moringa leaves extracts had a great effect on Cryptosporidium-infected ileal tissue explants. There was a high significant (P < 0.001) increase in IFN-γ, IL-12 and IL-14 (375, 275 and 90 pg/ml, respectively) in the supernatants of infected non-treated ileal tissue explant culture plate wells compared to the control non-infected ones (74.66, 75 and 50 pg/ml, respectively). A concentration of 100 mg/ml Moringa extract exhibited the highest anticryptosporidial effect causing a significant decrease in IFN-γ, IL-12 and IL-14 levels (225, 150 and 65 pg/ml, respectively) compared with supernatants of infected non-treated ileal explant culture plate wells. In this study, explant culturing of buffalo ileal tissues allowed investigating the pathogenesis of cryptosporidiosis using light and scanning electron microscopy and studying changes in cytokine levels in tissues with and without Moringa leaves extract treatment. This model could help to understand the regulation of intestinal secretory and inflammatory responses, and could be useful for the screening of potential anticryptosporidial candidate compounds.

Comparative ovicidal activity of Moringa oleifera leaf extracts on Fasciola gigantica eggs

BACKGROUND

Fasciolosis is an important zoonotic disease affecting the productive performance of farm animals in Egypt.

AIM

The aim of the present study was comparing the ovicidal effect of different extracts as an alcoholic (Methanolic and Ethanolic) and aqueous Moringa oleifera leaf extracts on Fasciola gigantica non-embryonated and developed eggs.

MATERIALS AND METHODS

Tested concentrations of extracts ranged from 12.5 to 800 mg/ml. Nitroxynil was used as reference drug with a dose of 100 mg/ml.

RESULTS

M. oleifera alcoholic and aqueous extracts showed a concentration-dependent ovicidal effect on F. gigantica non-embryonated and developed eggs. Based on LC50 values, water extract showed the highest ovicidal activity since it registered the lowest values of 2.6 mg/ml on non-embryonated eggs. Non-embryonated eggs were more susceptible to aqueous extract than developed eggs. On the other hand, the developed eggs were more susceptible to ethanolic extract than non-embryonated eggs even the lowest LC50 (12.38 mg/ml).

CONCLUSION

M. oleifera leaf extracts especially aqueous extract could be a promising step in the field of controlling fascioliasis. Further, in vivo studies are needed to enlighten the therapeutic potential of M. oleifera extracts in treating F. gigantica infection.

Protective effect of Eimeria stiedae coproantigen against hepatic coccidiosis in rabbits

Immunization of rabbits against hepatic coccidiosis was tried. The animals were immunized twice with Eimeria stiedae coproantigen in freund's adjuvant with two week intervals. The rabbits were challenged orally with sporulated E. stiedae oocysts one week post last injection. The protection was assessed by number of oocysts output, number of focal liver lesions, clinical sings and antibody response. The immunization resulted in 70% protection from infection and decline in oocysts count. High level of IgG response in immunized rabbits than control infected ones was occurred and being responsible for the recorded protection. The electrophoretic make up of the coproantigen and oocyst antigen showed different patterns of separation. Common as well as specific bands to each antigen were identified. Using the rabbit sera after 3 weeks post vaccination in immunoblot assay, immunogenic components were detected of molecular weight 155, 103, 74, 66, 44, 22KD with coproantigen and 155, 115, 57, 26 KD with oocyst antigen. While, the rabbit sera after 2 and 4 weeks post challenge reacted with oocyts antigen, in immunoblot assay, revealing immunogenic bands of molecular weight 155, 115, 57, 26, 22KD and 155, 115, 57, 25 KD respectively. Bands of 22KD and 155KD are partially responsible for eliciting host protective immune response where they were recognized by immunized sera in coproantigen and by immunized infected sera in oocyst antigen.

Trichinella spiralis: affinity purified antigen based diagnosis and immunoprophylaxis

The current research introduces a trial to develop vaccine candidate against trichenosis. A method of affinity chromatography was adopted to purify a Trichinella spiralis larval extract. The isolated fraction resolved into six bands of 148 KDa, 133 KDa, 118.5 KDa, 101 KDa 98.5 KDa and 79.5 KDa as observed by SDS-PAGE. The diagnostic value of this fraction was checked against antibodies regularly collected from rats experimentally infected with trichinosis compared with that of crude larval extract by ELISA. The crude extract detected the antibodies as early as one week post infection and the maximum level was recorded four weeks post infection. The advantage of the isolated fraction over the crude extract in trichinosis diagnosis was clearly observed at high serum dilution reached to 1:4000. The protective value of the isolated fraction was also investigated. Rats immunized subcutaneously with affinity purified larval extract with Freund's adjuvant showed reduction in worm burden reached to 82%. IgG antibody response in immunized rats was higher than that of control infected animals as measured by ELISA. This response might be partially responsible for the observed protection.

Identification and diagnostic evaluation of cross-reactive antigen between hydatid cyst fluid of Echinococcus granulosus and Trichinella spiralis larval extract

A cross reactive fraction was isolated from hydatid cyst fluid antigen of E. granulosus using CNBr Sepharose 4B affinity chromatography in which anti-T. spiralis antibodies were coupled with the column. Biochemical characterization of the isolated fraction included the use of SDS-PAGE, isoelectric focusing and amino acid analysis. The fraction showed 5 polypeptides of 165, 95.5, 63.5, 30.6 and 24 KDa. The isoelectric points of these polypeptides were 7.8, 7.2, 6.7, 6.2 and 5.7. The fraction exhibited 17 amino acids and was rich in tyrosine (20.81) and glutamic (15.28) ug/100 mg. The fraction proved higher potency in the diagnosis of experimental trichinellosis in rats than echinococcosis in dogs by ELISA. All experimentally infected animals reacted positively, recording 100% diagnostic sensitivity. Collectively, the present study proved that the hydatid cyst fluid cross-reactive fraction could be used in the diagnosis of trichinellosis at different intervals of infection and as early as 1 week post infection.

Cross-protection induced by cross-reactive antigen against Fasciola gigantica and Trichinella spiralis infections

Trichinella spiralis /Fasciola gigantica cross-reactive fraction was purified from T. spiralis larval extract by affinity column chromatography in which CNBr-Sepharose 4B was coupled with F. gigantica antibodies. The fraction consisted of six polypeptides of 191KDa, 178KDa, 149KDa, 106KDa, 101KDa and 32 KDa as revealed by SDS-PAGE. Analysis of the free amino acids of the fraction revealed 17 amino acids with high proportions of tyrosine and glutamic. Immunization of rabbits subcutaneously with the cross-reactive fraction in Freund's adjuvant followed by challenge with F. gigantica metacercariae resulted in reduction in worm burdens reached to 47.8%. While immunization of rats with the same fraction in Freund's adjuvant followed by infection with T. spiralis larvae resulted in reduction in worm count reached to 74%. IgG antibody response in rabbits increased due to immunization to reach its maximum value at the time of infection and then decreased gradually up to the end of the experiments. But. remained higher than the level in non vaccinated control animals. In rat sera, IgG level increased due to vaccination but the level recorded its optimum value one week post infection and then decreased. Thus the cross-reactive antigen proved cross-protection with the protection inducing capability against both diseases.