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Cloning and characterization of two recombinant Neospora protein fragments and their use in serodiagnosis of bovine neosporosis.

ABSTRACT: Bovine neosporosis causes fetal abortion and/or congenital neurologic disease in cattle. For the serodiagnosis of this parasitic disease, two immunodominant clones from a bovine Neospora lambda gt11 library were identified, characterized, and expressed as recombinant proteins for the development of an enzyme-linked immunosorbent assay (ELISA). These two clones, designated N54 and N57, were 29 and 20 kDa, respectively, when expressed as histidine fusion proteins from the pRSET expression vector. Antibodies to recombinant protein N54 recognized five major bands from a Neospora tachyzoite lysate with molecular masses of 97, 87, 77, 67, and 64 kDa. Antibodies to recombinant protein N57 recognized four primary bands with molecular masses of 34, 31, 30, and 28 kDa. When a defined "gold standard" panel of bovine sera from confirmed Neospora-positive and Neospora-negative cattle were characterized by immunoblotting, 57 of the 60 Neospora-positive serum samples recognized proteins with the molecular masses of the N54 heptuplet. Binding to the N57 quadruplet was more variable. The same gold standard panel was used to evaluate and compare an N54-based ELISA, an N57-based ELISA, and a whole-tachyzoite lysate-based ELISA. The sensitivities and specificities were 95 and 96% (N54 ELISA), 82 and 93% (N57 ELISA), and 74 and 93% (lysate ELISA). Thus, compared to the whole-tachyzoite lysate-based ELISA, both recombinant-protein-based ELISAs had higher sensitivities and higher or the same specificities and can be used to replace the whole-tachyzoite lysate ELISA for the serodiagnosis of bovine neosporosis.

SUBMITTER: Louie K

PROVIDER: S-EPMC170642 | biostudies-other | 1997 Nov

REPOSITORIES: biostudies-other

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Cloning and characterization of two recombinant Neospora protein fragments and their use in serodiagnosis of bovine neosporosis.

Louie K K Sverlow K W KW Barr B C BC Anderson M L ML Conrad P A PA

Clinical and diagnostic laboratory immunology 19971101 6

Bovine neosporosis causes fetal abortion and/or congenital neurologic disease in cattle. For the serodiagnosis of this parasitic disease, two immunodominant clones from a bovine Neospora lambda gt11 library were identified, characterized, and expressed as recombinant proteins for the development of an enzyme-linked immunosorbent assay (ELISA). These two clones, designated N54 and N57, were 29 and 20 kDa, respectively, when expressed as histidine fusion proteins from the pRSET expression vector. ...[more]

PMID: 9384291

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Project description:A 30-kDa major outer membrane protein of Ehrlichia canis, the agent of canine ehrlichiosis, is the major antigen recognized by both naturally and experimentally infected dog sera. The protein cross-reacts with a serum against a recombinant 28-kDa protein (rP28), one of the outer membrane proteins of a gene (omp-1) family of Ehrlichia chaffeensis. Two DNA fragments of E. canis were amplified by PCR with two primer pairs based on the sequences of E. chaffeensis omp-1 genes, cloned, and sequenced. Each fragment contained a partial 30-kDa protein gene of E. canis. Genomic Southern blot analysis with the partial gene probes revealed the presence of multiple copies of these genes in the E. canis genome. Three copies of the entire gene (p30, p30-1, and p30a) were cloned and sequenced from the E. canis genomic DNA. The open reading frames of the two copies (p30 and p30-1) were tandemly arranged with an intergenic space. The three copies were similar but not identical and contained a semivariable region and three hypervariable regions in the protein molecules. The following genes homologous to three E. canis 30-kDa protein genes and the E. chaffeensis omp-1 family were identified in the closely related rickettsiae: wsp from Wolbachia sp. , p44 from the agent of human granulocytic ehrlichiosis, msp-2 and msp-4 from Anaplasma marginale, and map-1 from Cowdria ruminantium. Phylogenetic analysis among the three E. canis 30-kDa proteins and the major surface proteins of the rickettsiae revealed that these proteins are divided into four clusters and the two E. canis 30-kDa proteins are closely related but that the third 30-kDa protein is not. The p30 gene was expressed as a fusion protein, and the antibody to the recombinant protein (rP30) was raised in a mouse. The antibody reacted with rP30 and a 30-kDa protein of purified E. canis. Twenty-nine indirect fluorescent antibody (IFA)-positive dog plasma specimens strongly recognized the rP30 of E. canis. To evaluate whether the rP30 is a suitable antigen for serodiagnosis of canine ehrlichiosis, the immunoreactions between rP30 and the whole purified E. canis antigen were compared in the dot immunoblot assay. Dot reactions of both antigens with IFA-positive dog plasma specimens were clearly distinguishable by the naked eye from those with IFA-negative plasma specimens. By densitometry with a total of 42 IFA-positive and -negative plasma specimens, both antigens produced results similar in sensitivity and specificity. These findings suggest that the rP30 antigen provides a simple, consistent, and rapid serodiagnosis for canine ehrlichiosis. Cloning of multigenes encoding the 30-kDa major outer membrane proteins of E. canis will greatly facilitate understanding pathogenesis and immunologic study of canine ehrlichosis and provide a useful tool for phylogenetic analysis.

Dataset Information

Cloning and characterization of two recombinant Neospora protein fragments and their use in serodiagnosis of bovine neosporosis.

Publications

Cloning and characterization of two recombinant Neospora protein fragments and their use in serodiagnosis of bovine neosporosis.

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