Detection of Bm86 antigen in different strains of Boophilus microplus and effectiveness of immunization with recombinant Bm86

The control of tick populations by using conventional strategies poses several problems, including the appearance of organophosphate resistant strains, among others. The possibility of using alternative strategies such as vaccination with tick antigens has been suggested by several authors. One particular antigen (Bm86) has been described and shown to be able to induce a protective immunity against the cattle tick Boophilus microplus. In this paper we demonstrate by means of immunohistochemical staining that this antigen is conserved among several strains of this species. These results correlate with those showing that animals vaccinated with a preparation of recombinant Bm86 were protected against challenge with the four different strains tested, including one resistant to organophosphates. These results favour the immunization with recombinant Bm86 for the control of the cattle tick B. microplus.     

Paramyosin: a candidate vaccine antigen against Schistosoma japonicum

Paramyosin, a 97 kDa myofibrillar protein, is a candidate vaccine antigen for prevention of infection with the human parasite Schistosoma mansoni . To determine if paramyosin would also induce protection against Schistosoma japonicum , paramyosin was biochemically purified from S. japonicum adult worms. SDS-PAGE demonstrated a single protein with a molecular weight of 97 kDa. In four separate experiments, vaccination of mice with S. japonicum paramyosin without adjuvant induced significant resistance (62%–86%, P < 0.001) against cercarial challenge as compared to controls. These data suggest that S. japonicum paramyosin may represent a candidate vaccine for immunization against schistosomiasis japonica.     

Vaccination with‘concealed’antigens: myth or reality?

Cattle infested with the tick Boophilus microplus produce antibodies to intrinsic membrane glycoproteins of the tick, as well as to Bm86, a well characterized antigen from the tick gut. Several factors explain how cattle could produce antibody to such antigens, which one would expect to be 'concealed' from the host's immune system, during natural infestation. It has been shown that the carbohydrate determinants on many tick glycoproteins are cross-reactive immunologically and that the reaction of bovine antibodies with intrinsic membrane glycoprotein is at least partially blocked by low molecular weight carbohydrate. Further, antisera from cattle exposed to ticks react with a glycosylated, native Bm86 but not with a non-glycosylated, recombinant Bm86. Thus the reaction of concealed antigens with antibodies produced as a result of tick infestation appears to be due to a relatively non-specific reaction with carbohydrate determinants on tick glycoprotein. Evidence is also presented that antibodies directed against carbohydrate determinants of Bm86 are not protective. Care must therefore be exercised in interpreting the results of antibody reaction with glycoproteins in such complex organisms.     

Cloning, expression and immunoprotective efficacy of rHaa86, the homologue of the Bm86 tick vaccine antigen, from Hyalomma anatolicum anatolicum

The Bm86 homologue of Hyalomma anatolicum anatolicum Izatnagar isolate was cloned and expressed in methylotropic yeast Pichia pastoris as intracellular, glycosylated and particulated form. It was named as rHaa86, the first recombinant protein of H. a. anatolicum . Seven epidermal growth factor-like domains predicted in Haa86 were structurally similar with that of its Bm86 counterpart. The identity between the corresponding EGF like domains of Bm86 and Haa86 were ranging from 51·3% to 78·3%. The molecular weight of the rHaa86 was 120–140 kDa, with possible 50–70 kDa glycosylation. The purified rHaa86 was characterized immunologically and evaluated for its immunoprotective potential against homologous challenge infestation in three groups of cross-bred calves. The immediate rejection percentage of females of H. a. anatolicum was 36 5%, 12·4% and 10·1% fed on immunized (group 1), adjuvant control (group 2) and untreated control (group 3) calves, respectively. The percent rejection of female ticks fed on immunized calves was 24·1% and 26·4% higher than for the ticks fed on control groups 2 and 3, respectively ( P <  0·05). The reduction of number of females, mean weight of eggs, adult females and efficacy of immunogen were 58·0%, 9·0%, 5·0% and 61·6%, respectively. The mean reproductive index of females fed on group 1 calves was significantly lower ( P <  0·05) than the females fed on the control groups and 44% reduction in the number of engorged larvae was recorded from the group 1 calves. The data demonstrated that rHaa86 antigen based vaccine could serve as one of the effective components in the integrated control of H. a. anatolicum.     

Experimental vaccination of sheep and cattle against tick infestation using recombinant 5′‐nucleotidase

Limited prior evidence suggests that 5′‐nucleotidase, an ectoenzyme principally located in the Malpighian tubules of the tick Rhipicephalus (Boophilus) microplus, could be an effective antigen in an anti‐tick vaccine. To assess this, recombinant 5′‐nucleotidase was expressed in Escherichia coli and used in vaccination trials with both sheep and cattle. Vaccinated sheep were challenged with freshly moulted adult ticks. Those with high titres of anti‐nucleotidase antibodies showed significant protection against tick infestation, although protection was less than that found with the previously characterized antigen, Bm86. Cattle were vaccinated, in separate groups, with 5′‐nucleotidase, Bm86 and both antigens combined. Cattle, as the natural host, were challenged with larval ticks. Although Bm86 showed typical efficacy, no significant protection was seen in cattle vaccinated with 5′‐nucleotidase. Cattle receiving a dual antigen formulation were no better protected than those receiving Bm86 alone. One possible reason for the difference between host species, namely antibody titre, was examined and shown to be an unlikely explanation. This demonstrates a limitation of using a model host like sheep in vaccine studies.     

Comparative vaccination of cattle against Boophilus microplus with recombinant antigen Bm86 alone or in combination with recombinant Bm91

Cattle were vaccinated either with a single recombinant tick antigen, Bm86 or with a combination of two recombinant antigens, Bm86 and Bm91 from the tick Boophilus microplus . In three experiments, the responses of cattle to subsequent challenge with the tick were assessed. The addition of the Bm91 antigen enhanced the efficacy of the vaccination over that with Bm86 alone to a statistically significant degree. Moreover, co-vaccination with two antigens did not impair the response of cattle to the Bm86 antigen. Finally, responses of individual cattle to the two antigens were independent. All of these results may be relevant to the increase in efficacy expected from a dual antigen vaccine.     

Evaluation of recombinant protein r140, a polypeptide segment of tegumental glycoprotein Sm25, as a defined antigen vaccine against Schistosoma mansoni

To investigate the role of tegumental glycoprotein Sm25 in protective immunity against schistosomiasis, codons 43-182 of its gene (GP22) were amplified by PCR and cloned in the pET 15b bacterial expression system. Recombinant protein r140 was inducibly expressed in the presence of rifampicin and purified by Ni-affinity chromatography. In different vaccination trials, Balb/c mice and Fischer rats repeatedly immunized with r140 in combination with one of several adjuvants (alum, cholera toxin or complexed into proteosomes) produced high titre anti-r140 responses. These antibodies detected an N-glycanase sensitive, 25 kDa antigen in a detergent solubilized worm fraction using Western immunoblotting. The choice of adjuvant affected the isotype distribution of the specific anti-r140 antibodies. Despite the presence of high antibody titres and isotypes which have been shown to correlate with protective immunity, protection against subsequent cercarial challenge was not observed. In addition, no appreciable effects on worm sex ratios or liver egg yields were detected in mice. Studies involving biotin labelling of membrane proteins in live worms showed that the majority of anti-r140 reactive molecules present in adult schistosomes are biotinylated after permeabilization of the parasite surface. Several possibilities to account for the lack of protective immunity are analysed .     

Cloning and expression of a protective antigen from the cattle tick Boophilus microplus.

Glycoproteins located on the luminal surface of the plasma membrane of tick gut epithelial cells, when used to vaccinate cattle, are capable of stimulating an immune response that protects cattle against subsequent tick infestation. One such tick gut glycoprotein, designated Bm86, has been purified to homogeneity and the amino acid sequences of peptide fragments generated by endoproteinase Lys-C digestion have been determined. We report here the isolation and characterization of a cDNA that encodes Bm86. The nucleotide sequence of the cDNA contains a 1982-base-pair open reading frame and predicts that Bm86 contains 650 amino acids including a 19-amino acid signal sequence and a 23-amino acid hydrophobic region adjacent to the carboxyl terminus. The main feature of the deduced protein sequence is the repeated pattern of 6 cysteine residues, suggesting the presence of several epidermal growth factor-like domains. A fusion protein consisting of 599 amino acids of Bm86 and 651 amino acids of beta-galactosidase was expressed in Escherichia coli as inclusion bodies. Ticks engorging on cattle vaccinated with these inclusion bodies were significantly damaged as a result of the immune response against the cloned antigen.     

Intradermal immunization of rats with plasmid DNA encoding Schistosoma mansoni 28 kDa glutathione S-transferase

Direct administration of plasmid DNA encoding an antigen represents an attractive approach to vaccination against infectious diseases, particularly in developing countries where easy-to-handle and cost-effective vaccines are needed. We have investigated the potential of DNA immunization to induce a specific antibody response against Schistosoma mansoni , using plasmid-DNA encoding the protective antigen, S. mansoni 28 kDa glutathione S-transferase (Sm28GST). Since S. mansoni parasite penetrates into its host through the skin, this tissue was chosen for plasmid DNA delivery. Following plasmid DNA administration into the skin of rats, the parasite antigen was detected in skin cells by immunohistochemistry. Three administrations of 200 μg plasmid at 14 day intervals led to the induction of a long-lasting specific IgG antibody response in the sera of immunized rats, with a predominance of IgG2a and IgG2b subclasses. Sera of immunized animals were able to mediate antibody-dependent cellular cytotoxicity in vitro , leading to the specific killing of parasite larvae. A parasite challenge performed on plasmid DNA-immunized animals induced a strong and rapid boosting effect on the specific IgG antibody response. These results demonstrate the potential of genetic immunization via the skin with plasmid DNA encoding Sm28GST for inducing immune responses with protective patterns against an S. mansoni infection .     

Immunization against malaria with antigen from Plasmodium falciparum cultivated in vitro.

Aotus monkeys, which are generally killed when infected with the human malaria parasite Plasmodium falciparum, have been identified and grouped by karyotype. These animals were immunized with parasite material obtained from P. falciparum cultivated in vitro which had been maintained in culture for over a year. When sufficient amounts of this antigenic material were used with a synthetic muramyl dipeptide (MDP), protective immunity was induced without presenting the antigen in complete Freund's adjuvant.     

日本血吸虫未成熟卵可溶性抗原的初步分析

采用ＳＤＳ－ＰＡＧＥ和ＥＬＩＢ技术分析了日本血吸虫未成熟卵可溶性抗原（ＳＩＥＡ），并与可溶性成熟卵抗原（ＳＥＡ）进行比较，二者主要蛋白区带存在明显差异，同时，ＥＬＩＢ结果表明，ＳＩＥＡ中感染血清和免疫血清所识别的６５ｋＤａ、６２ｋＤａ、５０ｋＤａ、２８ｋＤａ和和２６ｋＤａ等抗原组分不出现于ＳＥＡ，推测其在ＳＩＥＡ诱导宿主产生抗雌虫生殖及抗卵胚发育免疫应答方面起作用。     

阴道毛滴虫致病株可溶性抗原的电泳分析

目的：研究阴道毛滴虫一致病分离株的全虫可溶性抗原。方法：应用SDS－PAGE、激光光密度扫描、免疫印迹法等，对阴道毛滴虫一致病虫株的全虫可溶性抗原进行分析。结果：SDS－PAGE分离出14条蛋白带，在所分离的可溶性抗原中，分子量≤72kDa的占89．5％，分子量为48－51kDa的占19．2％，＞100kDa的占7．4 ％，最低分子量为13kDa。免疫印迹试验显示免疫反应具有广泛性分子量范围，但在86kDa附近未显示出免疫反应。结论：在阴道毛滴虫一致病虫株全虫可溶性抗原中，分子量为48kDa蛋白质具有较高的蛋白含量和较强的免疫学反应。     

Immunization of owl monkeys with a recombinant protein containing repeated epitopes of a Plasmodium falciparum glycophorin-binding protein.

A Plasmodium falciparum glycophorin binding protein (GBP-130) has been implicated in protective immunity to malaria. The gene for GBP-130 encodes a protein containing 11 tandemly repetitive 50 amino acid units. We report an immunization trial in Aotus monkeys using a recombinant DNA protein containing three of these 50 amino acid repeats. When administered with aluminum hydroxide, this antigen induced low levels of antibodies that reacted with the recombinant protein by ELISA and with parasite antigens in immunoblot and immunofluorescence assays, but not by immunoprecipitation. When administered with Freund's complete adjuvant, this antigen induced high levels of antibodies that reacted in ELISA, immunoblot, immunofluorescence, and immunoprecipitation assays. Serum from immunized monkeys did not inhibit parasite growth, and protection from intravenous challenge with P. falciparum-infected erythrocytes was not observed in any experimental group. These results suggest that the repetitive region of GBP-130 is not a useful vaccine candidate.     

Vaccination against enteric bacterial diseases

We review evidence that the systemic and mucosal immune systems of the body are compartmentalized. The development of immunity against an antigen at one mucosal surface may lead to the appearance of that immunity at other mucosal surfaces. In order to attain good protective immunity against a bacterial enteropathogen, it may be necessary to induce such immunity through the mucosal immune system of the gut. Earlier attempts to elicit protective immunity against bacterial enteropathogens by parenteral vaccination are reviewed. The modern approach involves oral administration of antigen. Such antigen may consist of killed bacteria or--more effectively--live, attenuated bacteria bearing antigens of interest. Such bacteria may be enteropathogens attenuated by mutation, either general or site-directed, or hybrid strains in which a bacterial carrier expresses an antigenic determinant of interest from cloned DNA. While good progress has been made in the comprehension of the requirements for effective vaccination against enteropathogenic bacteria, future work will produce more effective carrier strains than are currently available.     

Effective immunization against cutaneous leishmaniasis with recombinant bacille Calmette-Guérin expressing the Leishmania surface proteinase gp63.

Leishmania parasites cause a spectrum of diseases that afflict the populations of 86 countries in the world. The parasites can survive within the lysosomal compartments of the host's macrophages, unless those macrophages are appropriately activated. Despite the fact that protective immunity can be induced by vaccination with crude parasite preparations, little progress has been made toward a defined vaccine for humans. In this study the gene encoding the Leishmania surface proteinase gp63 was cloned and expressed as a cytoplasmic protein in a bacille Calmette-Guérin (BCG) vaccine strain. BALB/c and CBA/J mice were inoculated with a single dose of recombinant BCG and challenged with infective Leishmania major or Leishmania mexicana promastigotes. Significant protection was observed in both mouse strains against L. mexicana and in CBA/J against L. major, whereas only a delay in L. major growth was seen in BALB/c mice. Recombinant BCG also engendered a strong protective response against challenge with amastigotes of L. mexicana, demonstrating that the induced immune response recognized the intracellular form of the parasite. The results support the view that recombinant BCG expressing gp63 may prove a useful vaccine for inducing protective cell-mediated immune responses to Leishmania species causing American cutaneous leishmaniasis.     

致弱尾蚴免疫血清与日本血吸虫不同发育阶段抗原免疫反应性的研究

目的　通过比较分析日本血吸虫不同发育阶段抗原的异同 ,并以致弱尾蚴免疫血清识别不同发育阶段抗原 ,筛选具有保护性免疫作用的抗原分子。方法　分离制备日本血吸虫未成熟虫卵、成熟虫卵、尾蚴、雄性成虫、雌性成虫等不同发育阶段的抗原 ;采用ELISA分别测定正常尾蚴感染兔血清、紫外线照射致弱尾蚴免疫兔血清抗原的抗体水平 ;通过SDS PAGE电泳和免疫印迹技术 ,分析正常尾蚴感染血清与紫外线照射致弱尾蚴免疫兔血清对不同发育阶段的免疫反应性。结果与结论　SDS-PAGE结果显示未成熟虫卵抗原、成熟虫卵抗原、尾蚴抗原、雄性成虫抗原、雌性成虫抗原蛋白之间互有异同。间接ELISA试验显示致弱尾蚴免疫血清同样能诱导宿主产生高滴度的抗体水平。致弱尾蚴免疫血清共筛选出 2 3种具免疫学活性的抗原分子 ,分子量分别为 :2 4 .5kDa、2 8kDa、36kDa、4 3kDa、4 4kDa、4 8kDa、5 4kDa、5 8.5kDa、6 0kDa、6 2kDa、6 6kDa、6 8kDa、70kDa、75kDa、79kDa、85kDa、87kDa、91kDa、95kDa、97kDa、10 5kDa、10 8kDa、110kDa。其中未成熟虫卵和成熟虫卵抗原各占 11种 ,尾蚴抗原分子 4种 ,雄性成虫抗原分子 3种 ,雌性成虫抗原分子 6种 ,提示这些抗原分子可能为抗日本血吸虫病疫苗候选分子的重要靶标     

Extracellular vesicles induce protective immunity against Trichuris muris

Gastrointestinal nematodes, such as Trichuris trichiura (human whipworm), are a major source of morbidity in humans and their livestock. There is a paucity of commercially available vaccines against these parasites, and vaccine development for T. trichiura has been impeded by a lack of known host protective antigens. Experimental vaccinations with T. muris (murine whipworm) soluble Excretory/Secretory (ES) material have demonstrated that it is possible to induce protective immunity in mice; however, the potential for extracellular vesicles (EVs) as a source of antigenic material has remained relatively unexplored. Here, we demonstrate that EVs isolated from T. muris ES can induce protective immunity in mice when administered as a vaccine without adjuvant and show that the protective properties of these EVs are dependent on intact vesicles. We also identified several proteins within EV preparations that are targeted by the host antibodies following vaccination and subsequent infection with T. muris. Many of these proteins, including VWD and vitellogenin N and DUF1943‐domain‐containing protein, vacuolar protein sorting‐associated protein 52 and TSP‐1 domain‐containing protein, were detected in both soluble ES and EV samples and have homologues in other parasites of medical and veterinary importance, and as such are possible protective antigens.     

Purification and characterization of a 31 kDa mycobacterial excretory-secretory antigenic protein with a diagnostic potential in pulmonary tuberculosis

Proteins secreted into the culture medium by Mycobacterium tuberculosis are shown to be a source of antigens of immunodiagnostic importance. In our earlier study, we had reported a 31-37 kDa seroreactive gel-eluted antigenic fraction (ESAS-7), isolated from culture filtrate proteins of Mycobacterium tuberculosis H37Ra. In this report, we describe further purification of excretory-secretory ESAS-7 antigen fraction by fast protein liquid chromatography (FPLC) on Resource 'S' cation-exchange column and isolation of a more active and purified protein antigen fraction ESAS-7F. ESAS-7F antigen was characterized as a 31 kDa molecular weight glycoprotein containing a metallo-serine protease activity. N-terminal sequence analysis showed the first five amino acids as NTGQS (Asp-Thr-Gly-Glu-Ser). The present study helped in the isolation of a well characterized 31 kDa mycobacterial glycoprotein antigen with protease activity and diagnostic potential in detection of tuberculosis infection.     

Isolation and characterization of a 31 kDa mycobacterial antigen from tuberculous sera and its identification with in vitro released culture filtrate antigen of mtb H37Ra bacilli

Antigens released in vivo are of considerable interest in the immunodiagnosis of infectious diseases. Circulating antigen was isolated from bacteriologically confirmed tuberculous sera by ammonium sulphate precipitation. The protein fraction between 36%, and 75%, ammonium sulphate was reactive with tuberculosis (TB) sera showing the presence of circulating tubercular antigen (CTA). Fractionation of CTA on ultrogel AcA 34 gel filtration column gave 3 protein fractions CTA1, CTA2 and CTA3. CTA2 showed maximum antigenic activity by sandwich enzyme-linked immunosorbent assay (ELISA). SDS-PAGE fractionation and seroreactivity studies showed the presence of highly reactive tubercular antigen in CTA2-7 protein fraction by sandwich ELISA. Further fractionation of CTA2-7 on cation exchange fast-protein liquid chromatography (FPLC) gave 4 antigenic fractions, of which CTA2-7D was seroreactive similar to 31 kDa antigen (ESAS-7F) isolated from in vitro culture medium. Furthermore, CTA2-7D could inhibit binding of in vitro released ESAS-7F to affinity purified antibodies in inhibition ELISA. CTA2-7D antigen may be used as a target antigen in confirming active tubercular infection. Biochemical characterization showed circulating antigen CTA2-7D to be a lipoglycoprotein is released in vivo. ESAS-7F as a glycoprotein is released in vitro culture.