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S A Hines

Publications and source records attributed to S A Hines.

At least 37 records · Page 2Linked to original sources
PubMed1993

Babesia bovis: characterization of the T helper cell response against the 42-kDa merozoite surface antigen (MSA-1) in cattle.

The Babesia bovis major merozoite surface antigen (MSA-1) is a 42-kDa integral membrane glycoprotein previously shown to induce immunodominant antibody responses in cattle protectively immune to B. bovis and to induce neutralizing antibody. Recent studies have also shown that MSA-1 B cell epitopes common to New World strains of B. bovis are not present in either Israel or Australia strains. To understand the potential role of this protein in protective immunity, T helper cell responses specific for MSA-1 were characterized in Babesia-immune cattle. Peripheral blood mononuclear cells from immune cattle proliferated against affinity-purified recombinant MSA-1 protein expressed in Escherichia coli. MSA-1 preferentially stimulated the growth of CD4+ T cells in cell lines cultured with antigen for 4 weeks. MSA-1-reactive cell lines responded to a membrane fraction of B. bovis merozoites, suggesting recognition of the native protein. However, B. bovis-reactive T cell lines and T helper clones established by stimulation with crude parasite membrane antigen failed to respond to recombinant MSA-1, indicating that this antigen is not immunodominant for T cells. The majority of MSA-1-specific T helper clones reacted to unfractionated merozoite membrane antigen from New World B. bovis strains, but none of the clones responded to Australia B. bovis or to a Mexico strain of Babesia bigemina. Several T helper clones produced low levels of cytokines when stimulated with concanavalin A and interleukin-2. Northern blot analysis revealed the expression of interleukin-2, interleukin-4, interferon-gamma, and tumor necrosis factor-alpha messenger RNA in mitogen-stimulated T helper clones, showing that the clones examined expressed an unrestricted T helper phenotype. We conclude that the MSA-1 protein, although serologically immunodominant and capable of inducing neutralizing antibodies as well as a T helper cell response, is not an immunodominant T cell antigen. Furthermore, the parasite strain specificity of the Th clones supports previous findings of extensive polymorphism in the MSA-1 glycoprotein and suggests that like B cell epitopes, T cell epitopes reside in a nonconserved portion of the protein.

Animals↗
PubMed1993

Babesia bigemina: isolation and characterization of merozoite rhoptries.

Babesia bigemina apical membrane polypeptide p58, encoded by a multigene family with homologues in other Babesia spp. and sequence similarity to rhoptry proteins in other apicomplexan parasites, was identified within merozoite rhoptries using immunoelectron microscopy. To identify additional B. bigemina rhoptry proteins, rhoptries were isolated from French pressure cell-disrupted merozoites fractionated by differential centrifugation and isopycnic sucrose density gradient centrifugation. A fraction with a density of 1.16 g/ml contained club-shaped, electron-dense, membrane-bound organelles. Organelles were identified as rhoptries based on the following criteria: (1) density and morphology similar to those of rhoptries isolated from other apicomplexan parasites, (ii) dimensions similar to those of B. bigemina rhoptries in intact merozoites, and (iii) reactivity with an anti-p58 monoclonal antibody, but not with a monoclonal antibody against the merozoite outer membrane. Immunization of mice with isolated rhoptries induced antibodies that reacted with B. bigemina merozoites in an apical immunofluorescence pattern and bound the rhoptries in immunoelectron microscopy. Immunoprecipitation of [35S]methionine-labeled B. bigemina merozoites with the anti-rhoptry mouse serum identified at least seven putative rhoptry polypeptides including p58 (apparent molecular masses of > 225, 190, 76, 69, 58, 54, 36 kDa). The anti-B. bigemina rhoptry serum did not immunoprecipitate any proteins from [35S]methionine-labeled Babesia bovis merozoites consistent with previous observations that members of the Babesia rhoptry gene families do not encode B-cell epitopes conserved between species.

Animals↗
PubMed1993

Isolate-specific parasite antigens of the Babesia bovis-infected erythrocyte surface.

Bovine erythrocytes taken from in vitro cultures of Babesia bovis parasites from Mexico and the United States were assayed for the presence of new epitopes on the erythrocyte surface. New surface-exposed epitopes were detected by means of a whole-cell antigen capture assay. These epitopes were subsequently demonstrated only on infected erythrocytes by immunofluorescence staining of intact, living cells. Parasite-synthesized antigens were identified on each isolate using a surface-specific immunoprecipitation technique to analyze metabolically-labeled infected erythrocytes. In the Mexico isolate these antigens were 120 kDa and 107 kDa, whereas in the United States isolate polypeptides of 135, 120 and 107 kDa were detected. In each of these assays, reaction of immune sera with the infected erythrocyte surface was found to be isolate-specific.

Animals↗
PubMed1993

Failure of pulmonary clearance of Rhodococcus equi infection in CD4+ T-lymphocyte-deficient transgenic mice.

Pulmonary clearance of Rhodococcus equi requires functional T lymphocytes. In this study, CD8+ T-lymphocyte-deficient transgenic mice cleared virulent R. equi from the lungs while infection in CD4+ T-lymphocyte-deficient transgenic mice persisted. Although both CD4+ and CD8+ T cells function early in pulmonary defense against R. equi, clearance is dependent on CD4+ T lymphocytes.

Actinomycetales Infections↗
PubMed1993

Immunogenic B-cell epitopes of Babesia bovis rhoptry-associated protein 1 are distinct from sequences conserved between species.

Babesia bovis merozoite apical membrane polypeptide Bv60 was found to be rhoptry associated by immuno-electron microscopy and was redesignated rhoptry-associated protein 1 (RAP-1). The N-terminal 300 amino acids of RAP-1 have a high level of sequence similarity to the same N-terminal region of p58, its homolog from Babesia bigemina. However, the interspecies conserved sequences did not include RAP-1 surface-exposed B-cell epitopes as defined by monoclonal antibodies. Furthermore, neither heterologous B. bigemina immune nor monospecific anti-p58 bovine serum binds to whole RAP-1, indicating that the major B-cell epitopes recognized by these sera are also not encoded by the conserved sequences. Truncated RAP-1, expressed by a subclone encoding the N-terminal 235 amino acids, is weakly bound by antibodies in heterologous sera. A peptide representing the longest conserved amino acid sequence (amino acids 121 to 134) in this region is also weakly bound by antibodies in immune bovine sera, and rabbit antibodies induced by and strongly reactive with the peptide alone fail to bind native or denatured RAP-1. Thus, although the conserved region may contain one or more poorly immunogenic B-cell epitopes, these epitopes are inaccessible to antibody in whole RAP-1. The results indicate that the major immunogenic B-cell epitopes of RAP-1, including surface-accessible epitopes bound by monoclonal antibodies, are distinct from the conserved sequences representing putative functional domains.

Amino Acid Sequence↗
PubMed1992

Surface epitope localization and gene structure of a Babesia bovis 44-kilodalton variable merozoite surface antigen.

Variation of Babesia bovis merozoite surface antigens occurs among geographic strains of the parasite. In this and a concurrent report, we investigate this variation at the gene and protein level. Using a monoclonal antibody (mAb 23/70.174), B. bovis gene sequences were identified that encoded a surface epitope of a 44-kDa merozoite surface antigen (MSA-2). This epitope is variably expressed among geographic isolates of B. bovis. Here, we describe the MSA-2 protein gene sequence, localize this surface epitope to a repeated amino acid sequence, and investigate the genomic organization of the gene in B. bovis strains from Mexico and Australia. The predicted protein sequence had hydrophobic regions at its amino and carboxy termini consistent with a signal peptide and a membrane anchor via glycosylphosphatidyl inositol, respectively. The surface epitope recognized by mAb 23/70.174 was localized within a 24-amino acid sequence which is repeated twice in tandem. Six different EcoRI bands hybridized to the MSA-2 gene sequence with varying intensities in genomic Southern blots of the homologous strain. Two of these appear to be alleles of the MSA-2 gene. Whereas 5' and 3' sequences of the MSA-2 gene sequence were detected in an Australia strain of B. bovis, internal gene sequences encoding the surface epitope were not. The 3' sequences of the MSA-2 gene also had significant sequence similarity with the MSA-1 gene of the Mexico strain B. bovis and a gene from the previously described BabR locus. These data indicate that the MSA-2 protein gene belongs to the BabR locus which encodes variable merozoite surface antigens.

Amino Acid Sequence↗
PubMed1992

Neutralization-sensitive merozoite surface antigens of Babesia bovis encoded by members of a polymorphic gene family.

Monospecific antibodies against native and recombinant versions of the major merozoite surface antigen (MSA-1) of Babesia bovis neutralize the infectivity of merozoites from Texas and Mexico strains in vitro. Sequence analysis shows that MSA-1 and a related, co-expressed 44 kDa merozoite surface protein (MSA-2) are encoded by members of a multigene family previously designated BabR. BabR genes, originally described in Australia strains of B. bovis, are notable because their marked polymorphism is apparently mediated by chromosomal rearrangements, but protein products of BabR genes have not previously been identified. The 3' terminal 173 nucleotides of the MSA-1 gene, including 60 nucleotides of untranslated sequence, are highly similar to the 3' terminal sequences of BabR 0.8 (84% identity) and MSA-2 (94% identity). Alignment of the predicted protein sequences demonstrates significant overall homology between MSA-1 and MSA-2, and between both proteins and the amino terminal BabR sequence. MSA-1 nucleic acid probes also hybridize weakly to genomic DNA from the Australia 'L' strain, even though this strain does not express merozoite surface epitopes cross-reactive with MSA-1 or MSA-2. Hybridization of these same probes to genomic DNA from the cloned Mexico strain reveals a pattern of bands compatible with two copies each of MSA-1 and MSA-2. Proteins encoded by this B. bovis gene family have been designated variable merozoite surface antigens (VMSA). The extent and mechanism of VMSA polymorphism among strains will be important when evaluating the role these surface proteins have in the host-parasite interaction, including immunity to blood stages.

Amino Acid Sequence↗
PubMed1991

Characterization of the gene encoding a 60-kilodalton Babesia bovis merozoite protein with conserved and surface exposed epitopes.

A clone expressing a surface exposed, conserved epitope of a 60-kDa merozoite polypeptide was identified in a cDNA library constructed from a cloned Mexico strain of Babesia bovis. Sequencing of the 1.9-kb insert (pBv60) revealed an open reading frame encoding a 65-kDa polypeptide with a signal peptide and a tandemly repeated region. Monoclonal antibody 23/56.156, which binds a surface exposed epitope on the native polypeptide, specifically immunoprecipitated [35S]methionine-labeled polypeptides ranging from 60-30 kDa from pBv60 directed transcription and translation. Antibodies raised in rabbits against recombinant polypeptide reacted with the live merozoite surface in a polar immunofluorescence pattern, immunoprecipitated the native 60-kDa polypeptide, and were used to deplete the polypeptide by adsorption from a preparation of native [35S]methionine-labeled merozoite antigen. Restriction enzyme analysis indicated a single gene copy and the absence of introns. Hybridization demonstrated the presence of the gene in Mexico, Australia 'L', and Texas strains of B. bovis, but not in Babesia bigemina. A slightly different hybridization pattern was present in uncloned Australia 'L' B. bovis, indicating sequence diversity in the Bv60 gene among isolates. Cloning and structural analysis of pBv60 provides a source of defined antigen for determining the role of conserved merozoite surface epitopes in protective immunity against babesiosis.

Amino Acid Sequence↗
PubMed1989

Molecular characterization of Babesia bovis merozoite surface proteins bearing epitopes immunodominant in protected cattle.

Eight surface-radioiodinated merozoite proteins from a cloned, pathogenic isolate of Babesia bovis can be immunoprecipitated by antibody from cattle that are completely protected against clinical babesiosis. Among these eight surface proteins, the 55- and 42-kDa molecules are biosynthetically labeled with [3H]glucosamine. The 42-kDa glycoprotein can also be labeled with [3H]myristic acid and partitions exclusively into the detergent phase in Triton X-114 extracts, indicating that it is an integral membrane protein and suggesting that it is anchored by a glycosylphosphatidylinositol moiety. Antibody-mediated protection against B. bovis merozoites most probably requires a high level of circulating antibody to ensure antibody-merozoite binding during the parasite's brief extra-erythrocytic phase. Antibodies in diluted sera selectively recognize the 120-, 85-, 55- and 42-kDa surface proteins. Only the 42-kDa integral membrane protein is reactive with serum antibodies diluted greater than or equal to 1:16,000. Thus, we hypothesize that these immunodominant proteins, especially the transmembrane 42-kDa glycoprotein, are important to the induction of the protective immune response and are candidates for an improved vaccine against babesiosis.

Animals↗
PubMed1987

Disseminated Mycobacterium paratuberculosis infection in a cow.

A cow with chronic diarrhea and weight loss caused by localization of Mycobacterium paratuberculosis in the intestinal tract (Johne's disease) had gross and microscopic changes indicative of a disseminated infection. A direct association between the remote lesions and the intestinal infection was shown by isolation of M paratuberculosis from renal tissue, detection of intracellular M paratuberculosis antigen(s), using an indirect immunoperoxidase method, and by the characteristic granulomatous nature of the lesions. This case illustrates the potential for extra-intestinal lesions in M paratuberculosis infection of cattle and should cause veterinarians to consider mycobacterial disease when confronted with multinodular lesions of the bovine kidney. The immunoperoxidase method was useful in determining the cause of the inflammatory lesion in which intact organisms were not evident.

Animals↗
PubMed1987

Peripheral lymphedema in ferrets infected with Brugia malayi.

This study examines the production and persistence of peripheral lymphedema in ferrets experimentally infected with Brugia malayi. In 14 of 18 ferrets inoculated 2 or more times with infective larvae, lymphedema developed in the inoculated paw or paw and lower leg. In 5 of these ferrets lymphedema had persisted for 8 to 18 months at the time of necropsy. Lymphedema rarely was observed following a single inoculation of larvae or in microfilaremic ferrets. The results suggest that the ferret may be a useful experimental animal for the study of chronic lymphostatic disorders in filariasis.

Animals↗
PubMed1986

Antibody and cellular immune responses to microfilarial antigens in ferrets experimentally infected with Brugia malayi.

Eleven of 15 ferrets experimentally infected with Brugia malayi became amicrofilaremic after a brief patency; only four ferrets remained patent after 6 months of infection and two of these ferrets developed a high, persistent microfilaremia. Blastogenic responses of peripheral blood lymphocytes to antigens of microfilariae (mf), assayed in vitro, demonstrated an antigen sensitivity at prepatent, patent and postpatent periods of infection. Lymphocytes from ferrets with high microfilaremia had elevated background responses in culture which were directly correlated with the number of circulating mf. This background response was attributed to antigenic stimulation by mf present in the lymphocyte cultures; addition of mf to cultures of lymphocytes from postpatent ferrets induced responses equivalent to those observed in microfilaremic ferrets. Lymphocyte responses to the mitogen, concanavalin A, did not differ significantly among microfilaremic, amicrofilaremic and uninfected ferrets. Antibody in IgG to antigens of mf measured by ELISA and by immunoblots from SDS-PAGE showed similar patterns of response in ferrets which became amicrofilaremic and in the few ferrets which remained microfilaremic. prausnitz-Kustner tests demonstrated no consistent differences in titers to microfilarial antigens between patent and amicrofilaremic ferrets. The results suggest a high level of immune responsiveness to antigens of mf in infected ferrets with no evidence of immunosuppression associated with prolonged microfilaremia or of major changes in immune responses with development of amicrofilaremic infections.

Animals↗
PubMed1986

A retrospective study of proliferative interstitial lung disease of horses in Florida.

Proliferative and fibrosing interstitial lung disease was diagnosed in 20 horses submitted for necropsy between 1982 and 1985. Most of the horses were foals ranging from 3 days to 6 months in age. Six adult horses were affected. The macroscopic and microscopic characteristics of the lesions consisted of proliferative interstitial pneumonia and were similar to those of atypical interstitial pneumonia of ruminants. Based on morphologic features of the lesions, a toxic etiology is suspected for the induction of this naturally acquired primary equine lung disorder, but could not be specifically discovered by historical information.

Animals↗
PubMed1986

A model for experimental bacterial cystitis in the dog.

To induce an experimental model of bacterial cystitis, ten preconditioned dogs underwent bladder irritation with a 0.1% alcoholic solution of salicylic acid followed in 24 hours by an intravesicular infusion of Proteus mirabilis. The dogs were observed for the following 14 days (five dogs) and 17 days (five dogs) and then euthanatized and necropsied. Tenesmus, dysuria, hematuria, and pollakiuria occurred in all dogs, but the severity of these signs diminished with time. The total white cell, neutrophil, and monocyte counts in the peripheral blood increased and urinalysis results were consistent with infection and severe inflammation. The infection persisted for the duration of the study, although the average quantitative bacterial count in urine progressively declined. No changes occurred in the measured clinical chemistry values. Severe inflammation was present on gross examination of the bladder and microscopic examination of the bladder, prostate, and renal pelvis. Less severe inflammation was present on microscopic examination of the urethra and ureter.

Animals↗
PubMed1985

Endocarditis in six horses.

Six horses (five males) aged three months to fourteen years had endocarditis at necropsy. Two of the horses had a clinical diagnosis of valvular endocarditis with negative blood cultures. Single or complex valvular involvement was present in five horses. One horse had non-infectious thrombi associated only with the chordae tendineae. Mitral valves were affected in four horses, and aortic semilunar valves were affected in two. Infarcts had occurred in the kidneys and the myocardium of four horses. Bacteria were isolated postmortem from the valvular vegetations of two horses; Candida parapsilosis was isolated and demonstrated morphologically in a third horse.

Animals↗