Analysis of the expression and secretion of isotypes of sheep B cell immunoglobulins with a panel of isotype-specific monoclonal antibodies

Preparation of polyclonal anti-Schistosoma mansoni cysteine protease antibodies for early diagnosis

In many parts of the tropics, schistosomiasis is a major parasitic disease second only to malaria as a cause of morbidity and mortality. Diagnostic approaches include microscopic sampling of excreta such as the Kato-Katz method, radiography, and serology. Due to their vital role in many stages of the parasitic life cycle, proteases have been under investigation as targets of immunological or chemotherapeutic anti-Schistosoma agents. Five major classes of protease have been identified on the basis of the peptide hydrolysis mechanism: serine, cysteine, aspartic, threonine, and metalloproteases. Proteases of all five catalytic classes have been identified from S. mansoni through proteomic or genetic analysis. The study aimed to produce polyclonal antibodies (pAbs) against schistosomal cysteine proteases (CP) to be used in the diagnosis of schistosomiasis. This study was conducted on S. mansoni-infected patients from highly endemic areas and from outpatients' clinic and hospitals and other patients infected with other parasites (Fasciola, hookworm, hydatid, and trichostrongyloids). In this study, the produced polyclonal antibodies against S. mansoni cysteine protease antigens were labeled with horseradish peroxidase (HRP) conjugate and used to detect CP antigens in stool and serum samples of S. mansoni-infected patients by sandwich ELISA. The study involved 200 S. mansoni-infected patients (diagnosed by finding characteristic eggs in the collected stool samples), 100 patients infected with other parasites (Fasciola, hookworm, hydatid, and trichostrongyloids), and 100 individuals who served as parasite-free healthy negative control. The prepared pAb succeeded in detecting CP antigens in stool and serum samples of S. mansoni-infected patients by sandwich ELISA with a sensitivity of 98.5% and 98.0% respectively. A positive correlation was observed between S. mansoni egg counts and both stool and serum antigen concentrations. Purified 27.5 kDa CP could be introduced as a suitable candidate antigen for early immunodiagnosis using sandwich ELISA for antigen detection. KEY POINTS: • Detection of cysteine protease antigens can replace parasitological examination. • Sandwich ELISA has a higher sensitivity than microscopic examination of eggs. • Identification of antigens is important for the goal of obtaining diagnostic tools.

Role of anti-Giardia recombinant cyst wall protein IgG polyclonal antibodies in diagnosis and protection

Giardia duodenalis (G. duodenalis) is an infectious protozoan that has a global distribution especially in the hot climate. Around 200 million people are infected worldwide annually by Giardia, but infection is not always accompanied by symptoms, especially in endemic countries. Using traditional microscopy techniques in diagnosis, both in stool and water samples were less sensitive when compared to immunological methods; and the need for new diagnostic methods was necessary. Also, protection from infection is required in endemic areas. Therefore, the study aimed to produce anti- G. duodenalis IgG polyclonal antibodies (pAbs) by immunizing rabbit by G. duodenalis cyst recombinant protein. The produced antibodies were evaluated in the detection of G. duodenalis antigens in patients' stool and water samples from endemic areas across River Nile; where pAbs were used as a coating and a peroxidase conjugate antibody in sandwich ELISA. Moreover, pAbs were tested for the protection of mice from giardiasis. Sandwich ELISA using pAb has succeeded in the detection of G. duodenalis coproantigens in stool samples by a sensitivity of 97% and a specificity of 92.72%. Moreover, G. duodenalis cyst was detected in only seven water samples by ordinary microscopy; while sandwich ELISA revealed nineteen positive results. IgG pAb (1/200 µg/ml) protected mice from giardiasis; which was evident from the reduction in cysts and trophozoites numbers. We recommended the use of sandwich ELISA to monitor water quality, investigate environmental contamination and diagnosis in patients' stools. The pAbs can be prepared in large amount and used in field diagnosis and protection. This will help in the early diagnosis of G. duodenalis in water, which in turn can control outbreaks in rural areas.

A model of respiratory syncytial virus (RSV) infection of infants in newborn lambs

Many animal models have been established for respiratory syncytial virus (RSV) infection of infants with the purpose of studying the pathogenesis, immunological response, and pharmaceutical testing and the objective of finding novel therapies and preventive measures. This review centers on a neonatal lamb model of RSV infection that has similarities to RSV infection of infants. It includes a comprehensive description of anatomical and immunological similarities between ovine and human lungs along with comparison of pulmonary changes and immune responses with RSV infection. These features make the newborn lamb an effective model for investigating key aspects of RSV infection in infants. The importance of RSV lamb model application in preclinical therapeutic trials and current updates on new studies with the RSV-infected neonatal lamb are also highlighted.

Combined Mini-Parasep SF and Nanogold Immunoassay Show Potential in Stool Antigen Immunodetection for Giardiasis Diagnosis

Covalent loading or directional binding of biomolecules on gold nanoparticles (AuNPs) could lead to better results than simple direct adsorption for an enhanced ELISA application. The use of Mini-Parasep solvent-free (SF) without ether or ethyl acetate for the clean and efficient concentration of protozoa cysts, it is a single-use device for in vitro diagnostic use only. In this work, we used Mini-Parasep SF for the detection of giardia cysts in comparison to direct smear and Merthiolate-Iodine Formaldehyde Concentration (MIFC) technique in addition to its use in antigen detection by AuNPs biomolecule loading using rabbit polyclonal antibodies (pAb) against purified Giardia antigen (PGA). As a result, Mini-Parasep SF was the most effective method for Giardia cyst detection and regarding optimization of Mini-Parasep antigen detection, our data showed increased sensitivity and specificity of nano-sandwich ELISA to 92% and 94% respectively and increased positive predictive value (PPV) and negative predictive value (NPV) to 88.64% and 95.91% respectively. In conclusion, this research provides that Mini-Parasep SF concentrator enhanced Giardia cyst detection and improved antigen preparation for AuNPs sandwich ELISA in giardiasis diagnosis. The advantages of this method are the short assay time and the raised accuracy of antigen detection providing concentrated samples without the risk of solvent use and being a disposable Mini-Parasep it helps in giardia antigen purification as well as raising the sensitivity and specificity of ELISA through binding AuNPs.

Molecular characterization and B cell membrane expression analysis of Fc fragment gene of goose IgY

A novel goose immunoglobulin υ chain (Igυ) Fc fragment gene was cloned from splenic tissue mRNA using RT-PCR. Deduced amino acid sequence data from different vertebrates revealed high similarity to IgY-Fc fragments of duck (91%) and chicken (64%). Molecular characterization showed that the goose IgY-Fc fragment was consistent with the definition of immunoglobulin, and had the same antigenicity to natural IgY. Flow cytometry and laser scanning confocal microscopy showed that the polyclonal antibody against GoυFc reacted with the membrane surface of B lymphocytes in peripheral blood, which indicates that IgY was expressed on the surface of B cells. Analyses of the gene sequence of the goose IgY-Fc fragment and expression of B cell membrane may provide insight into the evolution of the Ig heavy chain gene family and benefit future studies on the avian immune system.

Clinical evaluation and antibody responses in sheep after primary and secondary experimental challenges with the mange mite Sarcoptes scabiei var. ovis

In this work the clinical evolution and the specific serum IgG and IgE antibody responses in sheep after primary (n=10) and secondary (n=4) experimental challenges with the mange mite Sarcoptes scabiei var. ovis were studied. The primary infection was characterized by the development of mange lesions in all sheep, a detection of live S. scabiei mites in 70% skin scrapings taken in week 10 post-challenge (PC), strongly raised and sustained specific IgG levels and a more moderate but continuous rise in specific IgE levels. Seroconversion was detected for IgG and IgE by ELISA in 90% and 60% of the sheep in week 8 PC, respectively. By Western-blotting (WB), ten IgG-reactive bands (36-120 kDa) and four IgE-reactive bands (90-180 kDa) were observed in week 8 PC. Following the secondary challenge the ewes developed a smaller area of mange lesion than that seen following primary challenge and live S. scabiei mites were not detected in skin scrapings collected in week 8 PC, suggesting that sheep had developed immunity to re-infection. Compared to primary infection, the specific IgG secondary antibody levels were transient, but in contrast there was an anamnestic IgE response, resulting in an elicitation of specific serum IgE levels in week 2 PC significantly higher than those demonstrated after primary infection. WB analysis revealed one additional IgG-reactive band (180 kDa) and no additional IgE-reactive bands. Determining the immunodiagnostic or vaccination value of the IgG-reactive antigens and IgE-reactive allergens detected requires further studies.

Identification of an antigen from the sheep scab mite, Psoroptes ovis, homologous with house dust mite group I allergens

Infestation of sheep with the ectoparasitic mite Psoroptes ovis, results in a severe allergic dermatitis. Currently, little is known about the allergens/antigens that stimulate the allergic response. We have isolated an 836-bp cDNA from a P. ovis cDNA library which displays strong homology to cysteine proteases and, in particular, to the group I house dust mite allergens Der p 1, Der f 1 and Eur m 1. The cDNA was expressed in Escherchia coli, fused to a hexahistidine tag and the recombinant protein (Pso o 1) purified using a nickel-affinity column. The recombinant Pso o 1 was tested for recognition by immunoglobulin (Ig)G and IgE in serum from P. ovis naïve and P. ovis infested sheep. Using Western blots, both classes of antibody to Pso o 1 were detected in postinfestation serum. In enzyme-linked immunosorbent assays, a pronounced IgG-antibody response to Pso o 1 was detected in five of five sheep 3 weeks postinfestation. The IgE-antibody response to whole mite extract was poor in four of five animals. However, a marked IgE response occurred in the fifth animal, and IgE anti Pso o 1 was detected in the serum.

Ovine chlamydial abortion: characterization of the inflammatory immune response in placental tissues

Ovine chlamydial abortion is a serious cause of fetal mortality in several sheep-rearing countries. The causal agent, Chlamydophila abortus (Chlamydia psittaci), does not generally induce clinical signs in the ewe other than abortion; this is associated with macroscopically visible damage in the placenta, which may be inflamed and thickened. To investigate the nature of the placental inflammation, seven pregnant sheep were inoculated subcutaneously at 70 days' gestation with C. abortus (strain S 26/3). A further five pregnant sheep received control inoculum by the same route at the same stage of pregnancy. Three of the infected ewes produced stillborn lambs and four produced live lambs. Lesions characteristic of chlamydial infection were present in all placentas except for two from one ewe that gave birth to twins. Histopathological examination of placental tissues from aborted fetuses showed a mixed inflammatory cell infiltrate with vasculitis and thrombosis in the mesenchyme of the intercotyledonary membranes. Cells expressing the macrophage-associated molecule CD 14 were found to be numerous, as were cells expressing major histocompatibility complex class II (MHC II) molecules. Many cells expressing messenger RNA (mRNA) encoding for tumour necrosis factor-alpha (TNF-alpha) were demonstrated, but few cells expressing interferon gamma mRNA and none expressing interleukin-4 mRNA were detected. The fetal immune response included small numbers of CD4+ and CD8+ cells, gamma delta T cells and B cells. It is concluded that abortion is the result of several factors, including destruction of tissue by C. abortus, vascular thrombosis, and an inflammatory response by the fetus. Production of TNF-alpha by fetal macrophages expressing MHC II molecules may be of considerable significance in the pathogenesis of abortion.

Local lung responses following local lung challenge with recombinant lungworm antigen in systemically sensitized sheep

BACKGROUND

Chronic mast cell-mediated inflammation may contribute significantly towards the extensive tissue remodelling that is a feature of lungworm infection in ruminants. Understanding the factors that control tissue remodelling is a necessary step toward effective management and treatment of conditions that feature such pathology.

OBJECTIVE

We sought to define in a novel ovine model system, the cellular, immune and mast cell phenotypic events that occur following local lung challenge with a recombinant protein antigen, DvA-1, derived from the ruminant lungworm nematode, Dictyocaulus viviparus.

METHODS

Two spatially disparate lung segments in systemically sensitized sheep were challenged on three occasions with DvA-1 (3xDVA) and two further segments were challenged with saline (3xSAL). Two months after the third challenge, one of the two segments previously repeatedly challenged with DvA-1 was challenged again with DvA-1 (3xDVA:DVA) whilst the other was challenged with saline (3xDVA:SAL). A similar protocol was followed with the saline challenged segments (3xSAL:SAL and 3xSAL:DVA). Bronchoalveolar lavage fluid (BALF) (n = 16) and tissue (n = 3) were collected after the last challenge.

RESULTS

Cellular changes 24 h after the fourth challenge were characterized by an increase in the absolute numbers of neutrophils and eosinophils in BALF from 3xDVA:DVA and 3xSAL:DVA segments. Local antibody production was implied through increased levels of antibody in both 3xDVA:DVA and 3xDVA:SAL segments, with the latter being unaffected by inflammation. Levels of active transforming growth factor beta-1 (TGF-beta(1)) were significantly increased in 3xDVA:SAL segments and a trend towards an increase was apparent in 3xDVA:DVA segments. Total TGF-beta1 levels were significantly correlated with eosinophil counts in all except the 3xDVA:SAL segments. Such changes in the bronchoalveolar space were complemented by increased ratios of sheep mast cell proteinase-1 expressing cells and tryptase expressing cells, to toluidine blue positive cells in airways from 3xDVA:DVA segments.

CONCLUSION

Mast cell phenotypic events occurring as a consequence of antigen challenge were limited to segments in which changes in BALF were characterized by neutrophil influx and increased local antibody production.

Theileria annulata: attenuation of a schizont-infected cell line by prolonged in vitro culture is not caused by the preferential growth of particular host cell types

Flow cytometry and monoclonal antibodies to bovine leucocyte surface antigens were used to identify the types of host cells that the sporozoites of Theileria annulata infect in cattle, to determine whether virulent schizont-infected cell lines (lines) differed phenotypically from avirulent lines, and to establish whether attenuation in vitro was accompanied by the preferential growth of particular host cell types. The surface antigens of four pairs of T. annulata (Ta) (Hisar) lines derived ex vivo and in vitro, including the virulent ex vivo-derived Ta Hisar S45 line, were consistent with a myeloid origin for all lines, irrespective of their derivation. The profiles of lines derived from cattle inoculated with a virulent line showed that the schizonts liberated from inoculated cells had transferred to myeloid cells. A number of other lines infected with different stocks of T. annulata expressed myeloid markers; a single line expressed CD21, a B cell marker. During prolonged in vitro culture, the parasites in the ex vivo (virulent)- and in vitro (avirulent)-derived Ta Hisar S45 myeloid lines became clonal, as defined by glucose phosphate isomerase (GPI) polymorphism, and the virulent line became attenuated. The two lines retained phenotypic profiles indicative of a myeloid origin but coexpressed some lymphoid antigens (CD2, CD4, CD8), although not CD3. Cloned schizont-infected lines, representing the three parasite GPI isotypes which constituted the virulent line, expressed similar patterns of myeloid and lymphoid markers to the virulent parent line. Some schizont-infected clones failed to establish as lines during the early weeks of culture because the cells died as the parasites differentiated into merozoites at 37 degrees C, the temperature at which schizont-infected cells normally grow exponentially. These results provided no evidence that prolonged culture induces preferential growth or loss of particular host cell types. However, a number of the alterations in host cell surface antigens induced by prolonged culture were shown to be linked to permanent changes in the parasite genome.

Two B cell subpopulations have distinct recirculation characteristics

This report describes two subpopulations of B cells in sheep. These subpopulations have distinct recirculation characteristics and tissue distributions. Phenotypically the populations are distinguished by their differential expression of the complement receptors, CD21 (CR2) and CD11b/CD18 (CR3). CD11b+ B cells are surface (s)IgMhi, co-express CD11c but are L-selectin negative. They populate the splenic marginal zone but are absent from splenic and ileal Peyer's patch (IPP) follicles and both afferent and efferent lymph compartments. Fluorescent tracing experiments showed that the CD11b+ B cells are non-recirculating as they did not appear in lymph after intravenous inoculation but are restricted to the blood and spleen. The CD11b-negative population expresses a conformational determinant of CD21 that is recognized by the monoclonal antibody Du 2-74. These cells are sIgMlo and co-express L-selectin. They populate the splenic and IPP follicles, are absent from the splenic marginal zone and are the only B cells in afferent lymph, efferent lymph and all lymph nodes. Fluorescence tracing experiments showed that the CD21 B cells are recirculating cells with their entry into efferent lymph being detectable by 16 h and peaking at 24-30 h. These data suggest that there are at least two lineages of B cells in the sheep with different phenotypic, functional and recirculation characteristics.