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Biomedical subjects

R McCandliss

Publications and source records attributed to R McCandliss.

17 recordsLinked to original sources
PubMed1992

Potential of a recombinant antigen as a prophylactic vaccine for day-old broiler chickens against Eimeria acervulina and Eimeria tenella infections.

A genetically engineered Eimeria tenella antigen (GX3262), produced as a fusion protein with beta-galactosidase and identified with a monoclonal antibody, induced partial but significant protection in young broiler chickens against experimental E. tenella and Eimeria acervulina infections. The antigen appears to share a T-helper cell epitope with the parasite as evidenced by (a) booster inoculation with either the recombinant antigen or with a small number of live oocysts enhanced the protective immunity in GX3262 primed chickens, and (b) ability of the antigen to induce in vitro stimulation of T-cells from chickens immunized with antigen or parasite. These observations suggest the feasibility of a single vaccination of 1 or 2-day-old broilers with GX3262 to induce an acceptable degree of protective immunity. The implications of the observations reported here are far reaching in terms of a practical coccidiosis vaccine for poultry, and show for the first time that 1-day-old broiler chickens can be efficiently vaccinated with a recombinant antigen against one or more species of Eimeria.

Amino Acid Sequence↗
PubMed1989

Characterization and vaccine potential of a novel recombinant coccidial antigen.

A cDNA clone derived from sporulated oocysts of Eimeria tenella and encoding the expression product GX3262 was identified using a monoclonal antibody raised against Eimeria acervulina sporozoites. The cDNA fragment containing the coccidial antigen gene was cloned in bacteriophage lambda gt11, transferred to a plasmid, and introduced into Escherichia coli for analysis of the gene products. The strain carrying the plasmid produced GX3262 as part of a fusion protein consisting of the first 1,006 amino acids of E. coli beta-galactosidase and 112 amino acids of the E. tenella protein of approximately 12 kilodaltons. Partially purified antigen, heat-killed recombinant bacterin, and live E. coli containing the recombinant coccidial antigen were used to immunize 1-week-old or newly hatched broiler chicks. Several immunization protocols were utilized, including boosts with partially purified beta-galactosidase-GX3262, bacterin, or small numbers of live E. tenella oocysts. After challenge with an experimental E. tenella infection, the birds were evaluated by scoring cecal lesions to determine the level of protection. The greatest degree of protection was seen after only a single immunization of 2-day-old birds with a live recombinant E. coli preparation. The results presented here identify GX3262 as a potential candidate coccidial vaccine antigen and provide evidence for the first time that newly hatched chickens can be successfully vaccinated with a recombinant antigen.

Amino Acid Sequence↗
PubMed1989

Genetically engineered antigen confers partial protection against avian coccidial parasites.

A fusion protein of beta-galactosidase and Eimeria tenella produced in a recombinant Escherichia coli strain was injected into chickens and elicited partial protection against an oral challenge with Eim. tenella parasites. The fusion protein contained a 31 kilodalton (kD) coccidial antigen designated as 5401. The DNA sequencing of the 5401 antigen-coding sequence revealed that this protein segment was highly negatively charged and strongly hydrophilic, and contained an amino-acid sequence repeated five times. A dose-titration study showed that immunizing chickens with a single subcutaneous injection of the 5401 antigen at 1,200 to 4,800 nanograms (ng)/bird in Freund's complete adjuvant decreased lesion scores, mortality, and feed conversions compared to unimmunized, challenged controls. Using the 1,200 and 2,400 ng/bird of the 5401 antigen, group weight gains were higher than for the unimmunized, challenged birds. In three other trials using the 5401 antigen at 2,400 ng/bird with light, medium, and heavy coccidial infections, significant protection was evidenced by reduced lesion scores, increased individual weight gains, or both. In addition, feed conversions were reduced when compared with unimmunized controls or birds immunized with a noncoccidial protein E. coli extract. Western blot analysis of sporozoite preparations with serum from 5401-immunized birds labeled two antigenic bands of 66 and less than 200 kD. These results indicate that the coccidial proteins produced in E. coli are potentially effective immunogens for protecting chickens against avian coccidiosis.

Amino Acid Sequence↗
PubMed1988

Synthesis of biologically active deletion mutants of human factor VIII:C.

The recent cloning and sequence analysis of human factor VIII:C (antihaemophilic factor) revealed a domain structure for the protein which can be presented as A1-A2-B-A3-C1-C2. In this report we describe the construction of two altered factor VIII:C cDNAs coding for molecules in which a part (amino acids 816 to 1598) or all of the B domain (amino acids 741 to 1689) was removed. In the latter mutant a new thrombin cleavage site has been created, which does not exist in wild-type factor VIII:C. The mutated cDNAs were cloned into eucaryotic expression vectors based on regulatory sequences of the virus SV40 and transfected into two different mammalian cell lines. Both truncated recombinant factor VIII:C molecules were secreted into the culture medium, showed full biological activity and could be activated by thrombin.

Amino Acid Sequence↗
PubMed1981

The structure of eight distinct cloned human leukocyte interferon cDNAs.

Eight classes of human leukocyte interferon (LeIFN) cDNA clones have been identified in a cDNA library prepared from a myeloblastoid cell line. The nucleotide sequences demonstrate that the multiple human LeIFN genes code for a family of homologous, yet distinct proteins. One of the cDNA clones may have been derived from the transcription of a LeIFN pseudogene.

Amino Acid Sequence↗
PubMed1981

Production of high levels of human leukocyte interferon from a continuous human myeloblast cell culture.

A myeloblast cell line has proved to be an excellent source of human leukocyte interferon. These cells, primed with interferon and induced with Sendai virus, produced optimal levels of human leukocyte interferon. The cells grew readily in spinner flasks and in medium containing horse serum. Interferon production over several months yielded an average titer of 2 X 10(5) reference units of interferon per 10(7) cells. The interferon produced by these cells appeared to be predominantly species of human leukocyte interferon. Since these cells seemed to consist of myeloblasts, it is clear that cells other than B-lymphocytes can produce leukocyte interferon.

Cell Line↗
PubMed1980

Human leukocyte interferon produced by E. coli is biologically active.

A human leukocyte interferon cDNA was enzymatically synthesized, inserted into the vector pBR322, and cloned in Escherichia coli. The DNA sequence codes for a 23-amino acid signal peptide followed by an interferon polypeptide of 165 amino acids. An expression plasmid was constructed which permits the synthesis in E. coli of 2.5 x 10(8) units of interferon per litre of culture. This LeIF protected squirrel monkeys from lethal encephalomyocarditis virus infection.

Amino Acid Sequence↗
PubMed1980

Construction and identification of bacterial plasmids containing nucleotide sequence for human leukocyte interferon.

Bacterial plasmids containing human leukocyte interferon sequences were constructed and identified. Identification was confirmed by correspondence of the nucleotide sequence with out amino acid sequence of human leukocyte interferon. The finding of bacterial recombinants containing distinct leukocyte interferon sequences is consistent with our purification of different leukocyte interferon species. We conclude that what has been designated human leukocyte interferon is, indeed, a class of homologous proteins. Preliminary indications suggest that their diversity appears to be represented by individual genomic equivalents. Each of the individual species exhibits characteristic activities. The structural modulation of these biological activities has immense significance for understanding the natural role of the interferons and for refining and developing their ultimate therapeutic potential.

Base Sequence↗