Annexin proteins PP4 and PP4-X. Comparative characterization of biological activities of placental and recombinant proteins

The human placental proteins PP4 and PP4-X, belonging to the annexin protein family, were expressed in Escherichia coli at high yield. The proteins were purified to homogeneity. The physicochemical parameters of the recombinant proteins were determined and compared with those of their natural placental counterparts. Except for a minor change in the pI, the proteins appeared to be indistinguishable by several criteria. Both recombinant PP4 and recombinant PP4-X were biologically active in a thromboplastin inhibition test and in a phospholipase A2 inhibition test.

N-glycosylated and unglycosylated forms of caprine trophoblast protein-1 are secreted by preimplantation goat conceptuses

Goat conceptuses secrete caprine trophoblast protein-1 (cTP-1) which is related antigenically to the abundant embryonic interferon-alpha II of sheep and cattle. Antiserum to ovine and bovine TP-1s immunoprecipitated three molecular weight classes (23,000, 21,000 and 17,000, each with two isotypes) of cTP-1 from goat conceptus culture medium. Cultures which contained tunicamycin resulted in a shift in the Mr = 23,000 and Mr = 21,000 forms to a Mr of 17,000. The Mr = 23,000 and 21,000 forms, but not the Mr = 17,000 form, bound to Concanaval in A-Sepharose and were eluted under conditions selective for glycoproteins bearing complex-type oligosaccharide(s). Thus cTP-1 is a mixture of glycosylated and unglycosylated polypeptides.

Binding of annexin V/placental anticoagulant protein I to platelets. Evidence for phosphatidylserine exposure in the procoagulant response of activated platelets

Proteins of the annexin/lipocortin family act as in vitro anticoagulants by binding to anionic phospholipid vesicles. In this study, we investigated whether annexin V (placental anticoagulant protein I) would bind to human platelets. Annexin V bound to unstimulated platelets in a reversible, calcium-dependent reaction with an apparent Kd of 7 nM and 5000-8000 sites/platelet. Additional binding sites could be induced by several platelet agonists in the following order of effectiveness: A23187 greater than collagen + thrombin greater than collagen greater than thrombin. However, neither ADP nor epinephrine induced additional binding sites. Three other proteins of the annexin family (annexins II, III, and IV) competed for annexin V platelets binding sites with the same relative potencies previously observed for binding to phospholipid vesicles. Phospholipid vesicles containing phosphatidylserine completely inhibited binding of annexin V to platelets. Annexin V completely blocked binding of 125I-factor Xa to thrombin-stimulated platelets. These results support the hypothesis that phosphatidylserine exposure occurs during platelet activation and may be necessary for assembly of the prothrombinase complex on platelet membranes.

The production, purification, and bioactivity of recombinant bovine trophoblast protein-1 (bovine trophoblast interferon)

Bovine trophoblast protein-1 (bTP-1) is a 172-amino acid interferon- alpha that has a role in maternal recognition of pregnancy in cattle. Here we describe production of bTP-1 by recombinant procedures in Escherichia coli. A bTP-1 gene was constructed which lacked the codons representing the signal sequence and provided a Met initiation codon ahead of the TGT codon encoding Cys1 of the mature protein. This construct was placed under the control of the Trp promoter within the expression vector pTrp2. Expression occurred optimally in E. coli D112 in the absence of tryptophan and in the presence of 0.5% acid-hydrolyzed casein (casamino acids) when 0.5 mM indole acetic acid was included in the medium. The bTP-1 was deposited in inclusion bodies and accounted for as much as 27% of the total cellular protein. The inclusion bodies were isolated by differential centrifugation and washed. The bTP-1 was solubilized by use of guanidinium-HCI and 2-mercaptoethanol and allowed to renature in air. Final purification was achieved by anion exchange chromatography on DEAE-cellulose. The yield of purified product, which had an antiviral activity greater than 10(8) international reference units/mg, was approximately 20 mg/liter. The recombinant bTP-1 was relatively stable to freeze-thawing and frozen storage, and could induce the production of an acidic protein of 70,000 mol wt in cultured explants of endometrium prepared from ewes on day 13 of the estrous cycle. The latter protein is a characteristic product of interferon-alpha action on uterine tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Purification of bovine trophoblast protein-1 complex and quantification of its microheterogeneous variants as affected by culture conditions

The bovine trophoblast protein-1 complex (bTP-1) is a group of glycosylated interferon-alpha 11, molecules secreted by the bovine conceptus that plays a critical role in preventing luteolysis during early pregnancy. In the current studies, secretion of individual variant forms of bTP-1 was quantified under a variety of culture conditions that could affect yields of bTP-1 for preparative-scale production of bTP-1. Additionally, a purification scheme for bTP-1 was developed. Conceptuses from Day 17 produced 13 proteins in the molecular weight and pI range characteristic of bTP-1, with 4-5 isoforms (pI = 5.6-6.6) at each of three molecular weight classes (21, 23.2 and 25.8 kDa). The major forms of bTP-1 were two variants of 23.2 kDa having pIs of 6.2 and 6.6. The relative proportion of bTP-1 variants was generally unaffected by culture conditions. Cultured conceptuses secreted bTP-1 at a sustained rate for 3 days and gaseous environment was without major effect on bTP-1 secretion. Conceptuses from superovulated cows also produced bTP-1 at Day 17 of pregnancy, suggesting that superovulation might be a useful method for increasing total bTP-1 yield per cow. The purification scheme that was developed utilized ultrafiltration with Centricon devices to achieve rapid molecular weight fractionation, desalting and concentration of conceptus secretory proteins prior to purification of bTP-1 using anion-exchange and gel filtration HPLC. The resultant preparation of bTP-1 included 9 variant forms of bTP-1 as well as a slight amount of a 45-kDa contaminant. Purified bTP-1 possessed antiviral activity but the specific activity was apparently reduced when conceptus-conditioned medium used for purification was stored for prolonged periods.

Characterization of one alpha 2-macroglobulin with anticomplementary activity from pregnant women

In 15 pregnant women during the third term of pregnancy, the immunomodulatory property of alpha 2-macroglobulin (alpha 2M) was initially detected by measuring the inhibitory effect on immune complement-dependent haemolysis of serum alpha 2M fractions obtained by gel filtration. By a two-step chromatography procedure consisting of gel filtration followed by anion-exchange chromatography, different sub-forms of alpha 2M in serum were separated. Amongst them, it was shown that the inhibition of complement activity was almost exclusively linked to one particular subform. Additional studies revealed that the observed effect was not due to proteases bound to alpha 2M during clotting since, by using protease-specific inhibitors, no change was observed in complement inhibition. This subform, though present at very low levels in control sera, appeared in strikingly increased amounts during the third trimester of pregnancy (35 mg/l) and comprised between 3 and 5% of the total alpha 2M. Results show that the increase of alpha 2M anticomplementary activity is linked to the increase in alpha 2M levels in serum.

Localization of an antiviral site on the pregnancy recognition hormone, ovine trophoblast protein 1

Ovine trophoblast protein 1 (oTP-1) is the interferon alpha (IFN-alpha) variant with potent antiviral activity and low toxicity that is responsible for maternal recognition of pregnancy in sheep. To examine the structure/function basis for the potent antiviral activity of oTP-1, we have exploited the direct approach of synthetic peptide competition with oTP-1 for receptor, using N-terminal oTP-1-(1-37) and C-terminal oTP-1-(139-172) peptides. These peptides possess structures similar to those predicted for the intact molecule on the basis of circular dichroism. oTP-1-(1-37) at 1.5 mM specifically blocked oTP-1 antiviral activity without affecting the antiviral activity of natural ovine IFN-alpha, recombinant bovine IFN-alpha, and recombinant human IFN-alpha. At concentrations as low as 0.15 mM, oTP-1-(139-172) blocked the antiviral activity of oTP-1, as well as that of natural ovine IFN-alpha, recombinant bovine IFN-alpha, and recombinant human IFN-alpha, but not recombinant bovine interferon gamma. Further, binding of radiolabeled oTP-1 to endometrial membrane preparations could be effectively inhibited by polyclonal anti-C-terminal and anti-N-terminal antisera, with the anti-C-terminal antiserum being the more effective inhibitor. Consistent with peptide and antiserum functional data, oTP-1 and recombinant bovine IFN-alpha are predicted to possess similar C-terminal structure but different N-terminal structure by composite surface profile predictions. The findings suggest that the C-terminal regions of IFN-alpha s bind to a common site on the IFN-alpha receptor while the N-terminal region binds to a site unique for the particular IFN-alpha.

Characterization of a human cDNA encoding a widely expressed and highly conserved cysteine-rich protein with an unusual zinc-finger motif

A human term placental cDNA library was screened at low stringency with a human prolactin cDNA probe. One of the cDNAs isolated hybridizes to a 1.8 kb mRNA present in all four tissues of the placenta as well as to every nucleated tissue and cell line tested. The sequence of the full-length cDNA was determined. An extended open reading frame predicted an encoded protein product of 20.5 kDa. This was directly confirmed by the in vitro translation of a synthetic mRNA transcript. Based upon the characteristic placement of cysteine (C) and histidine (H) residues in the predicted protein structure, this molecule contains four putative zinc fingers. The first and third fingers are of the C4 class while the second and fourth are of the C2HC class. Based upon sequence similarities between the first two and last two zinc fingers and sequence similarities to a related rodent protein, cysteine-rich intestinal protein (CRIP), these four finger domains appear to have evolved by duplication of a preexisting two finger unit. Southern blot analyses indicate that this human cysteine-rich protein (hCRP) gene has been highly conserved over the span of evolution from yeast to man. The characteristics of this protein suggest that it serves a fundamental role in cellular function.

NMR and ESR studies on human pregnancy zone protein. Comparison with human alpha 2-macroglobulin

NMR and ESR spectroscopies have been used to examine the plasma protease inhibitor pregnancy zone protein (PZP) and its complex with chymotrypsin. The 1H NMR spectrum of PZP shows relatively few sharp resonances, which, by analogy with human alpha 2-macroglobulin, probably arise from the proteolytically sensitive bait region. Upon reaction with chymotrypsin to form a 1:1 protease.PZP tetramer complex, there is a large increase in the intensity of sharp resonances due to an increase in mobility of these residues. 35Cl NMR has been used to follow binding of zinc and manganese to apo-PZP. Zinc binding causes a linear broadening of the bulk Cl-, consistent with access of Cl- to PZP-bound zinc. Since zinc in the two highest affinity sites in human alpha 2-macroglobulin causes no broadening of Cl-, it is concluded that these zinc sites are absent from PZP. The mobility of chymotrypsin in the PZP.chymotrypsin complex was examined by covalently attaching a nitroxide spin label at the serine residue in the active site of the enzyme and examining the appearance of the ESR spectrum. The chymotrypsin is rigidly held by the PZP to which it is covalently bound. In an analogous experiment performed previously on alpha 2-macroglobulin, chymotrypsin, bound in the presence of methylamine and therefore largely noncovalently bound, was found to be free to rotate inside the cage formed by the protease inhibitor.

Purification and characterization of six annexins from human placenta

Isolation of six calcium-binding proteins from human placenta is described by means of hydrophobic chromatography, calcium-dependent adsorption to heparin-Sepharose and ion-exchange chromatography. These proteins were characterized and identified as PP4, PP4-X, PAP III, p68 and lipocortins I and II belonging to the family of annexins. Antibodies raised against PP4, PAP III and p68 revealed to be highly specific, while those raised against PP4-X reacted with all investigated annexins, except PP4. Cross-reactivity was also observed between lipocortins I and II. All annexins inhibited in a concentration-dependent manner blood coagulation but with different potencies as was determined by means of a modified thromboplastin time test. The most potent inhibitors turned out to be PP4 and PAP III, followed by PP4-X, lipocortin I, p68 and lipocortin II.

Biochemical analysis of the rat MHC class I antigens RT1.Aa, RT1.Fa and Pa

In DA strain rats, there are two other MHC class I loci (Pa and RT1.Fa) in the vicinity of the classical class I locus RT1.Aa. The Pa antigen is the pregnancy-associated antigen, and it was detected by antibodies elicited in WF females pregnant by DA males without any other immunization. The Fa antigen was detected by a monoclonal antibody raised by alloimmunization. In the present work, the Aa, Fa and the Pa antigens have been compared by HPLC peptide mapping and by isoelectric focusing after their isolation by appropriate monoclonal antibodies. All the three antigens are identical in primary structure with respect to lysine, methionine, asparagine and the aromatic amino acid residues, but they differ from one another with respect to glutamic acid and/or aspartic acid residues. The pI values of the antigens differ slightly. All three antigens have two identical N-linked glycans, but the Fa antigen has an additional N-linked glycan. Based on the available amino acid sequence of the Pa antigen, it can be concluded that both Aa and Pa antigens are devoid of glycosylation in the second domain. This lack of glycosylation of the classical antigen Aa is unique for the rat, since classical class I antigens of the mouse show glycosylation in the first and second, and sometimes in the third domain, and those in the human, in the first domain only. The high degree of similarity among the Aa, Fa, and Pa molecules that this study indicates is also unique for the rat, since antigens encoded by different class I genes of the same haplotype are quite disparate in the mouse and human.

Identification, immunoaffinity purification and initial characterization of a novel 71 kD human decidua associated protein by use of specific monoclonal antibodies

This study is part of an ongoing attempt to identify and characterize proteins associated with the human decidual tissue. A novel decidual-associated glycoprotein with an apparent molecular weight of 71 kD named hDP71 (human decidual-protein 71), has been identified and purified by immunoaffinity technique using monoclonal antibodies. The monoclonal antibodies recognizing the hDP71 were raised against a partly purified preparation of decidual associated proteins, which was obtained by immunoabsorption of serum proteins from crude decidual extract. Although the hDP71 was copurified with another decidual-associated glycoprotein, the previously described hDP200 (Halperin et al., 1989), evidence is presented showing that the monoclonal antibodies described above are specific for hDP71.

Identification, immunoaffinity purification and partial characterization of a human decidua-associated protein

A crude extract of pooled early-pregnancy decidual tissue was enriched for soluble decidual proteins by exhaustive affinity absorption with antibodies to human serum proteins immobilized on Eupergit C. The partly purified extract was used to prepare monoclonal antibodies. A monoclonal antibody was obtained recognizing an antigen present in extract of decidual tissue and not in extract of proliferative endometrium. The monoclonal antibody was used for immunoaffinity purification of the decidua-associated protein. By SDS-PAGE analysis, under reducing conditions it yielded 2 bands at apparent molecular weights of 55,000 and 25,000. Under non-reducing conditions a single protein band at apparent molecular weight of 200,000 was observed. The Mr 200,000 protein was named hDP200 and the Mr 55,000 protein was named hDP55. It is suggested that hDP55 is a subunit of the hDP200. The hDP200 did not react with polyclonal antibodies specific for PP12 and PP14. PP14 has been shown to be immunologically indistinguishable from PEP and alpha 2-PEG. Our data therefore suggest that hDP200 is a novel human decidua-associated protein.

Major histocompatibility complex class I antigens expressed on rat trophoblast cells

There is controversy about the size of the major histocompatibility complex antigens of trophoblast cells from placenta. There are some reports that the heavy chains of these molecules are smaller (39-43 kd) than those of the classical class I antigens (45-46 kd), while there are others which show that both the light and the heavy forms of class I antigens occur in the trophoblast cells. In order to investigate this problem, we studied the classical class I antigen (RT1.Aa) and the pregnancy-associated class I antigen (Pa) of the rat from 125I-labeled basal trophoblast cells, isolated from the placenta of WF females pregnant by DA males, using very mild conditions. These antigens were compared with those of the syngeneic (DA x DA) trophoblast cells or paternal (DA) lymphocytes by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Both the Aa and Pa antigens, precipitated from the two trophoblast preparations, showed a heavy chain of 46 kd associated with a 12 kd beta 2-microglobulin component, as did the same molecules precipitated from the lymphocytes. Heavy chains in the range of 39-43 kd could not be detected in any of the samples. The results suggest that the smaller molecular weight heavy chains are methodological artifacts and could arise from loss of a glycan(s) during isolation.

[Purification and chemical characterization of pregnancy-specific beta 1-glycoprotein (SP1)]

A pregnancy-specific beta 1-glycoprotein (SP1) was purified from human placenta using either an ion-exchange column [method I] or an anti-SP1 antibody immunoadsorbent column [method II]. The yields were 5.2% with a total of 1.2 mg per placenta [method I], and 9. 4% with a total of 2.2 mg per placenta [method II], respectively. The physicochemical properties (molecular weight, sedimentation coefficient, amino acid composition etc.) of SP1 purified from human placenta by these methods are essentially the same as those of typical SP1. It is thus apparent from the present results that these SP1 from pregnant serum and human placenta cannot be distinguished immunologically and biochemically.

Differentiation-linked expression of the plasminogen activator inhibitor type-2 gene in the human HL-60 promyelocytic cell line

HL-60 is a human promyelocytic cell line which was found to be capable of differentiating toward a macrophage-like or granulocyte-like phenotype. Histochemical analysis demonstrated that incubation of cells in the presence of phorbol myristate acetate (PMA) or 1,25-dihydroxyvitamin D3 induced varying degrees of monocytic differentiation, while incubation in the presence of retinoic acid (RA) or dimethyl sulfoxide (DMSO) induced granulocytic differentiation. The differentiation induced by PMA, RA, and to a lesser extent DMSO, was accompanied by the induction of plasminogen activator inhibitor expression. mRNA analysis of control and PMA-induced cultures revealed the induction of a 2-kb message in treated cells which hybridized with a PAI-2-specific oligonucleotide probe. This is consistent with the literature concerning the expression of PAI by macrophages and granulocytes. No hybridization was detected with a PAI-1 specific probe. Expression of PAI by cells of hematopoietic origin appears to be associated with differentiation or stimulation of committed cells. Furthermore, PAI-2 expression by HL-60 cells is not restricted to one specific hematopoietic lineage. Since other cells of hematopoietic origin such as platelets express PAI-1, future studies using pluripotential cell lines could provide information on the initial events of lineage commitment and gene expression.

Intracellular distribution of a 32-KDa calcium-dependent phospholipid-binding protein from human placenta

A 32-KDa calcium dependent phospholipid-binding protein was purified to homogeneity from human placenta by affinity adsorption to polyacrylamide-immobilized phosphatidylserine followed by elution with 5 mM EGTA and ion exchange chromatography. Immunochemical studies using the polyclonal antibody against the 32-KDa protein revealed that this protein was present around the nucleus in the cytoplasm but not clearly associated with cell organelles and cytoskeletons. In KB cells treated with insulin, 32-KDa protein was localized in the ruffling membranes in addition to the cytoplasm. Purified 32-KDa protein was shown to coprecipitate with skeletal muscle actin under polymerizing conditions. These findings suggest that the 32-KDa protein interacts with networks of actin filaments in cells.

[Isolation of calphobindin-II and its mechanism of anticoagulant activity]

In addition to calphobindin-I (a placental coagulation inhibitor), another anticoagulant protein (calphobindin-II) was isolated from the EDTA extract of human placenta. The purified protein had a molecular weight of 68,000 daltons according to sodium dodecyl sulfate polyacrylamide gel electrophoresis under both reduced and non-reduced conditions. This protein prolonged prothrombin time, activated partial thromboplastin time and recalcification time, but did not affect thrombin time. This substance also inhibited both factor X activation by a complex of [factor VII-tissue factor-Ca2+] and factor II activation by a complex of [factor Xa-phospholipid-Ca2+]. This protein was a stronger anticoagulant than calphobindin-I.

Purification and characterization of endometrial protein PP14 from mid-trimester amniotic fluid

Two methods are described for the purification of placental protein 14 from human mid-trimester amniotic fluid. The first includes gel filtration, anion exchange chromatography, and reversed-phase high performance liquid chromatography. The second method employs octyl-Sepharose chromatography instead of high performance liquid chromatography, and it also includes an anti-hCG adsorption step in order to remove the remaining traces of hCG from the purified PP14. In the first method, 362 micrograms of PP14 was recovered from 26 ml amniotic fluid with a final recovery of 25%. In the second method, 745 micrograms of PP14 was recovered from 200 ml amniotic fluid with a final recovery of 9.8%. As a result of either method sodium dodecyl sulfate polyacrylamide gel electrophoresis of purified protein showed one band at 28 kDa. Polyclonal antibodies against placental PP14 reacted with this band in immunoblot analysis and radioimmunoassay. A single N-terminal amino acid sequence of M D I P Q T K Q D L E L P K L A G T W H S M A was obtained for the isolated protein. This sequence is identical to that previously reported for human placental PP14. Due to its high PP14 concentration amniotic fluid serves as an excellent starting material for purification of this protein.

Cloning and sequence determination of human placental aldose reductase gene

The human aldose reductase gene has been cloned by screening a human placental cDNA library with antibodies against bovine lens aldose reductase. The nucleotide sequence of the entire coding region has been determined. The deduced amino acid sequence indicates that the human enzyme is 84% identical to the bovine lens aldose reductase and 85% identical to the rat lens aldose reductase. It is also very similar to the human aldehyde reductase, the bovine prostaglandin F synthase, and to the European common frog rho-crystallin. The deduced amino acid sequence also indicates that maturation of aldose reductase involves removal of the N-terminal methionine.

Pure human inactive renin. Evidence that native inactive renin is prorenin

To clarify contradicting observations on the identity of inactive renin and prorenin, inactive renin was completely purified from native human chorion laeve and the culture medium of human chorion cells. A 720,000-fold purification with 14% recovery was achieved from chorion laeve in 6 steps, including immunoaffinity chromatography on a monoclonal antibody to human renin coupled to Protein A-Sepharose CL-4B. A 3,100-fold purification with 40% recovery was achieved from chorion culture medium in 4 steps, including immunoaffinity chromatography. Inactive renin purified from the two different sources migrated as a single protein band with the same molecular weight of 47,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and consisted of multiple components that could be resolved by isoelectric focusing. Both had the same pI values which shifted downward upon activation by trypsin; however, relative peak heights were different between the two preparations. The purified inactive renin from chorion laeve was completely inactive and did not bind to pepstatin-aminohexyl-Sepharose; however, that from chorion culture medium was partially active and completely bound to the pepstatin gel, indicating that each molecule is partially activated. Trypsin-activated inactive renins from both sources were identical with human renal renin in terms of pH optimum and Km. Specific activities of trypsin-activated inactive renin from chorion laeve and chorion culture medium were 529 Goldblatt units/mg of protein and 449 Goldblatt units/mg of protein, respectively. Amino acid sequence analysis of both of the purified inactive renin preparations demonstrated a leucine residue at the amino terminus. The sequence of 11 additional amino acids was identical in both and agreed with that predicted from the base sequence of the renin gene. These findings indicate that preprorenin is converted to prorenin following removal of a 23-amino acid signal peptide and that the native inactive renin, whose amino acid sequence commences with Leu-Pro-Thr..., is prorenin.

Molecular cloning and characterization of the human folate-binding protein cDNA from placenta and malignant tissue culture (KB) cells

Human folate-binding proteins (FBPs) are single chain glycoproteins that contain a high affinity binding site for folates and methotrexate and occur in a soluble or membrane-associated form. The membrane-associated FBP is involved in the uptake of physiologic folates and methotrexate. In this study, human FBP cDNA clones were isolated from human malignant nasopharyngeal carcinoma (KB) cell and placental cDNA libraries by means of oligonucleotide probes derived from determined internal amino acid sequences. The longest cDNA nucleotide sequence is 1126 base pairs and encodes a polypeptide that contains 257 amino acid residues (calculated molecular mass = 29,817). The deduced amino acid sequence is 80% homologous to a bovine soluble FBP, is greater than 99% homologous to the reported partial amino acid sequence of the human soluble FBP, contains three potential N-linked glycosylation sites, and has hydrophobic amino- and carboxylterminal regions which are consistent with a signal peptide and a potential membrane-anchoring domain, respectively. On Northern blot analysis, radiolabeled cDNA probes hybridize to a single 1100-base pair mRNA species that is expressed to a variable degree in human KB cells, placenta, brain, and epithelial mRNA but is not detectable in human liver mRNA. In vitro translation of RNA transcripts from the FBP cDNA inserts yields a 30-kDa and a 42-kDa polypeptide in the absence and presence of microsomal membranes, respectively.

Inactivation of the human immunodeficiency viruses (HIV-1 and HIV-2) during the manufacturing of placental albumin and gammaglobulins

A laboratory study was undertaken to verify the elimination and/or inactivation of the human immunodeficiency viruses HIV-1 and HIV-2 during the manufacture of placental albumin and the gammaglobulins Gamma 16 and Veinoglobuline. Nine steps of the process were selected for study. Samples of current production batches were taken at these different stages and a known quantity of virus was added. Each sample was then processed according to the production schedule for the corresponding step, and the residual viral activity was measured. In eight of nine steps, a complete viral clearance was achieved. Estimation of the cumulative infectivity reduction due to these nine steps is in the following range: greater than 12 to 16 log10 HIV-1 and greater than 17 to 19 log10 HIV-2 for Gamma 16, greater than 9 to 13 log10 HIV-1 and greater than 13 to 15 log10 HIV-2 for Veinoglobuline, and greater than 19.7 log10 HIV-1 and greater than 24 log10 HIV-2 for albumin. As many other purification steps were not included in this study, the real infectivity reduction capacity for the whole process probably exceeds these values. Nevertheless, the levels of inactivation measured clearly document a rigorous fractionation process that has a high assurance of killing or eliminating all contaminating virus.

Intrauterine infusion of highly enriched bovine trophoblast protein-1 complex exerts an antiluteolytic effect to extend corpus luteum lifespan in cyclic cattle

Intrauterine infusion of enriched bovine trophoblast protein-1 complex (bTP-1) resulted in extension of interoestrous intervals and corpus luteum function in cyclic cattle. Conceptus proteins were obtained by culture of Day 17-18 conceptuses for 72 h. Media from the first (n = 28), second (n = 26) and third (n = 19) 24 h of conceptus incubations were utilized. A highly enriched preparation of bTP-1 was obtained by a combination of ammonium sulphate precipitation, ion-exchange chromatography, and h.p.l.c. gel filtration. Degree of purity of the final preparation was confirmed by gel electrophoresis and immunoblotting with antiserum to ovine trophoblast protein-1. Jersey cattle (3 per group) received intrauterine infusions, twice daily from Day 15.5 to 21.0, of bovine serum albumin, the entire array of bovine conceptus secretory proteins (bCSP) from the 3 days of conceptus culture, or bTP-1. Infusions were via a catheter into the uterine horn ipsilateral to the corpus luteum. Oestrous cycle length in bTP-1-treated cows (26.1 +/- 1.3 days) was greater than for cows given BSA (19.5 +/- 1.3 days) or bCSP (21.5 +/- 1.3 days). Similarly, progesterone concentrations in serum remained elevated for a longer period of time for bTP-1-treated cows than for cows treated with BSA or bCSP. Residual variance associated with vena cava concentrations of PGF-2 alpha at Days 19-21 after oestrus (which included the variance between 15-min periods within cows) was reduced in cows treated with bTP-1 as compared to other groups. Lack of a bCSP effect may have been due to low amounts of bTP-1 in conceptus-conditioned medium from cultures of greater than 24 h. None the less, purified bTP-1 was effective in extending luteal function and appears to be the antiluteolytic agent of early pregnancy.

Purification of a functional 40 kD human placental Fc gamma-receptor using a monoclonal antibody

F(ab')2-fragments of a mouse monoclonal antibody (B1D6) reacting with placental receptors for the Fc part of IgG (FcR) were used as affinity reagents for the purification of an antigen from placental extract (PE). The antigen agglutinated ovine erythrocytes (E) sensitized with rabbit antibodies (A) (EA), but not E or E sensitized with F(ab')2-fragments. It reduced the EA rosette-formation with mononuclear cells and the binding of soluble immune complexes to placental tissue. The antigen bound to aggregated IgG and Fc-fragments of IgG, but not to native IgG or F(ab')2-fragments of IgG. The data indicate that the purified antigen possesses FcR activity with low affinity for IgG. SDS-PAGE and Western blot showed one distinct band of approximately 40 kD. The electrophoretic mobility did not change after reduction and the band reacted with concanavalin A indicating that the FcR are single-chained glycoproteins.