Antibody response in rabbits to immunization with Mycobacterium leprae.

Mycobacterium leprae purified from liver tissue of an infected armadillo (the A/10 preparation) was tested for antigenic composition by immunization of rabbits and characterization of the antibody response by crossed immunoelectrophoresis. The rabbit antisera detected seven distinct components in the M. leprae preparation. This number is far lower than in similar experiments with other mycobacteria. The M. leprae sonic extract gave far fewer lines after polyacrylamide gel electrophoresis and staining with Coomassie brillant blue than sonic extracts prepared from BCG, M. smegmatis, and M. phlei adjusted to the same protein concentration based on the Folin assay. The seven components detected in M. leprae cross-reacted extensively with M. avium, BCG, M. lepraemurium, M. smegmatis, and Nocardia asteroides. The seven components are involved in immune reactions in leprosy; antibodies against all of them were demonstrated in sera from patients with lepromatous leprosy, but the specificity of the antibodies varied from patient to patient. The reason for the demonstration of so few antigenic components and some of the implications of these findings for the use of armadillo-grown M. leprae to develop specific skin test reagents and in other aspects of leprosy research are discussed.     

V(H)3 antibody response to immunization with pneumococcal polysaccharide vaccine in middle-aged and elderly persons

Pneumococcal disease continues to cause substantial morbidity and mortality among the elderly. Older adults may have high levels of anticapsular antibody after vaccination, but their antibodies show decreased functional activity. In addition, the protective effect of the pneumococcal polysaccharide vaccine (PPV) seems to cease as early as 3 to 5 years postvaccination. Recently, it was suggested that PPV elicits human antibodies that use predominantly V_H3 gene segments and induce a repertoire shift with increased V_H3 expression in peripheral B cells. Here we compared V_H3-idiotypic antibody responses in middle-aged and elderly subjects receiving PPV as initial immunization or revaccination. We studied pre- and postvaccination sera from 36 (18 vaccine-naïve and 18 previously immunized subjects) middle-aged and 40 (22 vaccine-naïve and 18 previously immunized subjects) elderly adults who received 23-valent PPV. Concentrations of IgGs to four individual serotypes (6B, 14, 19F, and 23F) and of V_H3-idiotypic antibodies (detected by the monoclonal antibody D12) to the whole pneumococcal vaccine were determined by enzyme-linked immunosorbent assay (ELISA). PPV elicited significant IgG and V_H3-idiotypic antibody responses in middle-aged and elderly subjects, regardless of whether they were vaccine naïve or undergoing revaccination. Age did not influence the magnitude of the antibody responses, as evidenced by similar postvaccination IgG and V_H3 antibody levels in both groups, even after stratifying by prior vaccine status. Furthermore, we found similar proportions (around 50%) of elderly and middle-aged subjects experiencing 2-fold increases in V_H3 antibody titers after vaccination. Age or repeated immunization does not appear to affect the V_H3-idiotypic immunogenicity of PPV among middle-aged and elderly adults.Streptococcus pneumoniae is the leading cause of bacterial pneumonia and bacterial meningitis in the United States, resulting in 175,000 hospitalizations and 7,000 to 12,000 deaths annually. Groups with the highest incidences of pneumococcal infection include the very young, the elderly, persons who are immunocompromised, smokers, and certain other demographic groups (2, 8). In persons 65 years or older, the incidence of invasive pneumococcal disease (IPD) is around 50 per 100,000 individuals per year and is associated with a case fatality rate of 20%, whereas among those aged 85 years or older, the fatality rate increases to 40% (2, 34).The Advisory Committee on Immunization Practices recommends vaccinating all adults aged 65 years or older with the 23-valent pneumococcal polysaccharide vaccine (PPV). One-time revaccination for this age group is also recommended if subjects received their first dose ≥5 years previously and before the age of 65 years (6). A recent meta-analysis provided evidence supporting the recommendation for PPV to prevent IPD in adults. However, it did not provide compelling evidence to support the routine use of PPV to prevent all-cause pneumonia or mortality (15). In addition, significant protection against IPD seems to be lost as early as 3 to 5 years after vaccination in persons older than 65 years (28, 29).A common surrogate for antibody-mediated protection is the measurement of postvaccination IgG antibody to capsular polysaccharides contained in PPV. Validation of this measure may be disputed given the fact that even adequate IgG concentrations in the elderly may have significant reductions in antibody functional activity toward pneumococcal polysaccharide antigens (25). Molecular characterization of the immune response to pneumococcal polysaccharides is seldom performed in clinical vaccine studies (24); however, there is a large body of literature on this subject (3, 5, 7, 22, 38). Recent studies have demonstrated that PPV stimulates increased expression of variable region heavy chain family 3 (V_H3) genes in peripheral B cells from immunocompetent subjects, yielding serum polysaccharide-specific antibodies and/or B cells that express V_H3 (1, 7, 32, 33). V_H3 responses may also correlate with functional activity of antipneumococcal antibodies (3).Previous studies on gene expression of the total circulating B-cell population demonstrated a shift toward V_H4 and V_H1 expression in aging humans, compared with predominant V_H3 expression in young subjects (35). This repertoire shift has been postulated as a possible mechanism of decreased pneumococcal anticapsular antibody function in older populations. In this regard, a preliminary report (30) found lower levels of V_H3-idiotypic antibody responses to capsular polysaccharides from serotype 4, but not serotype 14, in the elderly than in young individuals. A subsequent study (11) of the V_H gene repertoire of human peripheral B cells specific for these two capsular polysaccharides (4 and 14) revealed that the responses in both age groups were dominated by the V_H3 gene family (>90%). The V_H1, V_H4, and V_H5 gene families were also isolated from both groups, but they constituted <10% of the total heavy chain repertoire. Given the attractiveness of the study of V_H3-idiotypic antibody responses to assess the immunogenicity of pneumococcal polysaccharide antigens and the need for further studies on its role in aging, we evaluated IgG and V_H3-idiotypic antibody responses after administration of PPV in sera from a subset of vaccine-naïve and revaccinated middle-aged and elderly subjects enrolled in a pneumococcal vaccine clinical trial (19).     

Antibody response to wild rubella virus structural proteins following immunization with RA 27/3 live attenuated vaccine

Summary Antibody response to individual structural proteins (E 1, E 2, and C) of the M-33 wild rubella virus strain was assayed by an immunoblot technique in 12 girls, following immunization with RA 27/3 live attenuated rubella vaccine. Of the 12 immunized subjects, before vaccination 9 had no demonstrable rubella specific antibodies while the remaining 3 had a low level of rubella specific antibodies, reacting only with the E 1 protein. At one month after vaccination all the immunized subjects presented anti-E 1, anti-E 2, and anti-C specific antibodies. However, at 1–2 weeks after vaccination the 9 girls who were seronegative before immunization still had no detectable antibodies to any of the rubella virus structural proteins, while the 3 subjects whose preimmunization sera had reacted with the E 1 protein presented an accelerated immune response, showing anti-E 2 and anti-C specific antibodies and a more intensely marked anti-E 1 specific band.     

Antibody response in the parotid fluid and serum of Irus monkeys (Macaca fascicularis) after local immunization with Streptococcus mutans.

The antibody response of Macaca fascicularis in parotid saliva and serum to local immunization by two routes with Streptococcus mutans was studied and compared over 1 year. Antibodies were titrated and classified by indirect immunofluorescent staining using specific antiglobulin conjugates. Antiglucosyltransferase activity was assayed by an enzyme inhibition test. Animals were immunized first by injecting formalin-killed bacterial cells and cell products subcutaneously into the vicinity of the four major salivary glands. The monkeys were next immunized by retrograde instillation of antigen into the parotid duct. Extensive subcutaneous local immunization gave a serum response only. After parotid duct immunization, high titers of immunoglobulin A (IgA) antibody, along with traces of immunoglobulin G (IgG) immunoglobulin M (IgM) antibody, appeared in the parotid saliva, and in the serum high titers of IgG antibody were present along with lower titers of IgA and IgM. IgA antibodies in parotid fluid were shown by double immunofluorescent staining to be associated with antigenic determinants which cross-reacted with an antiserum directed to human secretory component. Titers in parotid fluids and sera fell sharply when immunization was stopped. This response pattern was reproducible. High concentrations of antibody capable of inhibiting glucosyltransferase prepared from S. mutans were found in the sera, but relatively little was detected in the parotid fluids. Extensive immunization via the parotid duct resulted in transient functional impairment of the gland, as evidenced by diminished salivary flow rates. We conclude that parotid ductal immunization can be an effective method for stimulating a salivary secretory IgA antibacterial antibody response.     

Antibody response of mice to lactate dehydrogenase-elevating virus during infection and immunization with inactivated virus

BALB/c and Swiss mice were infected with lactate dehydrogenase-elevating virus (LDV) or immunized with glutaraldehyde-inactivated or ether-extracted virus and their plasma was monitored for anti-LDV IgG and IgM levels by ELISA and indirect fluorescent antibody staining, for neutralizing antibodies, for sensitized antibody-virus complexes, for immune complexes, and for total plasma IgG and IgM. In infected mice, anti-LDV IgM was transiently formed during the first 2 weeks post infection (p.i.) but only at a low level. Anti-LDV IgG was produced in a biphasic manner with an initial peak at about 10 days p.i. and a secondary rise reaching a maximum level 30-80 days p.i. which was retained throughout the persistent phase of infection. The concomitant appearance of comparable levels of low molecular weight immune complexes suggests that most anti-LDV IgG was complexed with LDV proteins. Also, as early as 10 days p.i., infectious antibody-LDV complexes developed, which were neutralizable by rabbit anti-mouse IgG, whereas antibodies that neutralize the infectivity of exogenously added LDV appeared only 1-2 months p.i. Throughout infection, most of the anti-LDV IgG was directed to VP-3, the envelope glycoprotein of LDV, which was found to exist in at least 10 distinct forms ranging in molecular weight from 24 to 42 kDa. Anti-LDV IgG levels as high as those observed in infected mice developed in mice immunized with inactivated LDV. Antibodies to glutaraldehyde-inactivated LDV were also mainly directed to VP-3, but exhibited no neutralizing activity. The polyclonal B cell activation associated with a persistent LDV infection and the formation of immune complexes were not observed in mice immunized with inactivated virus.     

Antibody response to Giardia muris trophozoites in mouse intestine.

The protozoan parasite Giardia muris colonizes the mouse small intestinal lumen. This parasite is cleared immunologically from the intestine of normal mice. In contrast, T-lymphocyte-deficient (nude) mice have an impaired immunological response to G. muris and become chronically infected. In the present study, trophozoites were harvested from the intestinal lumen of immunocompetent BALB/c mice and nude mice and examined for surface-bound mouse immunoglobulins by immunofluorescence microscopy. Immunoglobulin A (IgA) and IgG, but not IgM, were detected on trophozoites obtained from BALB/c mice, from day 10 of the infection onwards. Trophozoites from nude mice showed very little evidence of surface-bound mouse immunoglobulin at any time during the 5-week period immediately following infection of these animals with G. muris cysts. Intestinal G. muris infection was cleared by the BALB/c mice but not by the nude animals. The data suggest that parasite-specific IgA and IgG bind to G. muris trophozoites in the intestinal lumen of immunocompetent BALB/c mice. Intestinal antibodies that bind to trophozoite surfaces are likely to play an important part in the clearance of G. muris infection by immunocompetent mice. The inability of nude mice to clear this infection at a normal rate is likely to be due to impairment of Giardia-specific intestinal antibody production.     

Structural control of immunogenicity. II. Antibody synthesis and cellular immunity in response to immunization with mono-epsilon-oligo-L-lysines

A detailed evaluation of the capacity of mono-ε-DNP-oligo-L-lysines to initiate anti-DNP antibody synthesis and a state of delayed hypersensitivity in guinea-pigs is presented. Peptides containing as few as two lysine residues elicit the production of significant amounts of anti-DNP antibody when they are administered as Freund''s complete adjuvant emulsions. Under these immunization conditions, the serum concentration of anti-DNP antibody is dependent on the chain length of the peptide, and on the amount and kind of mycobacteria in the adjuvant; guinea-pigs lacking the PLL gene produce amounts of anti-DNP antibody indistinguishable from that produced by guinea-pigs possessing this gene. On the other hand, when guinea-pigs are immunized with either 1-ε-DNP-tetra-L-lysine or 1-ε-DNP-nona-L-lysine without the use of mycobacterial adjuvant, anti-DNP antibody is produced only by guinea-pigs receiving the nona-L-lysine and only by those animals possessing the PLL gene.Delayed hypersensitivity results from immunizing PLL+ guinea-pigs with mono-ε-DNP-octa and nona-lysines but not from immunization with mono-ε-DNP-hexa-lysine; PLL— animals do not exhibit delayed hypersensitivity to any of these compounds.The data suggest that antibody synthesis to positively charged compounds may proceed as a result of formation of charge complexes with mycobacterial proteins; under such immunization conditions the intrinsic immunogenicity of a compound is more reliably revealed by the induction or elicitation of cellular immune responses. On this basis, a definite discontinuity in the degree of immunogenicity of the mono-ε-DNP-oligo-L-lysines occurs as the peptides are lengthened from six to eight residues.     

Antibody response to different determinants on carcino-embryonic antigen (CEA)

Studies on the diverse nature of the immune response of animals to different antigenic determinants on CEA indicate that the type of antiserum used is of prime importance in determining differences or identities between antigens isolated from tumour and normal tissues. One type of antiserum against CEA shows cross-reactions with a normal colon antigen (NCA) found in both malignant and normal tissues. This finding confirmed that a common determinant is shared by both CEA and NCA. A second type of anti-CEA did not cross react with NCA but reacted only with CEA, providing evidence for a unique CEA determinant. Yet a third and most common type of antiserum to CEA reacted equally well with CEA and NCA and was unable to distinguish between the two. This third type of anti-CEA was completely absorbed with NCA. Failure to recognize this type of anti-CEA would lead to erroneous conclusions regarding the existence of a unique antigenic determinant on CEA.     

Cell-surface ganglioside GD2 in the immunohistochemical detection and differential diagnosis of neuroblastoma.

The expression of the disialoganglioside GD2 was analyzed in 67 solid tumors and normal tissues from children by using the GD2-specific murine monoclonal antibody 3A7 and the indirect immunoperoxidase method. GD2 was expressed in all of 28 neuroblastomas and was most abundant in stroma-poor tumors. In differentiating stroma-rich neuroblastomas, neuroblastic clusters, neurofibrils, and most ganglion-like cells were positive, whereas Schwann's-cell stroma did not express GD2. In ganglioneuromas, only a few ganglion-like cells showed GD2, whereas all other structures were negative. Scattered foci of ganglioside GD2 also were found in some non-neuronal tumors, such as rhabdomyosarcomas and osteosarcomas, but not in lymphomas, Askin tumors, or most Wilms' tumors. The monoclonal antibody 3A7 is a useful aid in the immunohistochemical diagnosis of neuroblastoma. In addition, the intense cell surface staining of neuroblastoma cells by this reagent makes it potentially useful for detecting residual neuroblastoma in bone marrow samples and lymph node biopsies.     

Various factors (allergen nature,mouse strain,CpG/recombinant protein expressed) influence the immune response elicited by genetic immunization

BACKGROUND: Genetic immunization is a very promising therapeutic approach for allergy treatment. In the present study we investigate the influence of the nature of the allergen, the mouse strain, and the relative amount of CpG to expressed recombinant protein on immune responses using two major peanut allergens, Ara h 1 and Ara h 4. METHODS: The cDNA of Ara h 1 and of an isoform of Ara h 4 were cloned and inserted in pcDNA3. Antigen specific IgG1, IgG2a and IgE were followed after genetic immunization with 100 microg of these clones in mouse strain SKH-Hr1 or BALB/c and with 1 microg of the clones+99 blank plasmid in SKH-Hr1. RESULTS: Genetic immunization in SKH-Hr1 with Ara h 1 elicited a classical Th1 type response, but Ara h 4 elicited a mixed Th1/Th2 response with high IgG1 and even IgE in some mice. In BALB/c both plasmids produced a high IgG1 level. Decreasing the amount of plasmid injected did not change the immune response profile. However, increasing the amount of CpG administered relative to the recombinant Ara h 4 protein expressed reversed the Th1/Th2 response pattern in SKH-Hr1 mice. CONCLUSIONS: Immune responses after genetic immunization are strongly influenced by the nature of the allergen, the mouse strain, and the ratio of CpG to recombinant protein expressed.     

Antibody response to human cytomegalovirus (HCMV) glycoprotein B (gB) in AIDS patients with HCMV end-organ disease

Human cytomegalovirus (HCMV)-specific antibody responses in HIV-1 infected individuals either with or without HCMV end-organ disease were examined to determine the whether development of HCMV disease was associated with a particular deficit in the antibody response. Anti-whole HCMV, anti-glycoprotein B (gB), and neutralizing antibody levels were higher in HIV-1 infected individuals than in healthy immunocompetent subjects, particularly in patients with AIDS either with or without HCMV-associated disease. Irrespective of location and spread of HCMV disease, patients who had received anti-HCMV therapy prior to sampling exhibited significantly higher anti-gB and neutralizing antibody titers than those who remained untreated. Likewise, patients with HCMV disease who were antigenemic or viremic had significantly lower anti-gB and neutralizing antibody titers than those who tested negative in either assay. Patients with untreated HCMV disease had significantly lower antibody titers than AIDS patients without disease. Analysis of the IgG subclass antibody responses to gB revealed no significant differences among HIV-1 infected individuals. These results suggest that levels of detectable anti-gB and HCMV neutralizing antibodies are inversely related to systemic viral load. Thus, antibodies with such specificities may be relevant in preventing the establishment of HCMV-associated disease or in modulating its progression. J. Med. Virol. 55:272–280, 1998. © 1998 Wiley-Liss, Inc.     

Antibody response in rats to the synthetic polypeptide (T,G)-A--L genetically linked to the major histocompatibility system

Various inbred strains of rats were immunized with the synthetic polypeptide (T,G)-A–L and showed considerable differences in their antibody response to this polymer. Further investigations using congenic strains, which differ at the major histocompatibility locus (H-1, Ag-B), and F₁ and F₂ hybrids of high and low responding strains demonstrated that the ability to respond to (T, G)-A–L is under the control of a dominant factor genetically linked to the H-1 locus.     

Antibody induced injury to podocytes with proteinuria and foot process swelling in a transgenic (T16) mouse

T16 mice contain a human 3' untranslated sequence of the Thy 1.1 gene. Unlike normal mice they express Thy 1.1 protein on the podocytes which was immuno-localized to podocyte apical and basal plasma membranes and filtration slit. When monoclonal anti-Thy 1.1 antibody (OX7) was injected in nonproteinuric heterozygous mice there was rapid podocyte foot process swelling and proteinuria. Immunofluorescence showed granular glomerular OX7 binding at one hour. Progressive loss of pedicels occurred with 17.9 +/- 2.5, 14.4 +/- 1.1 and 10.5 +/- 3.5 per 10 nm glomerular basement membrane (GBM) remaining 1, 6 and 24 hours, respectively, after 1 mg OX7, vs 32.2 +/- 2.0 in T16 mice given saline. Twenty-four hour proteinuria was OX7 dose-dependent, peaked at 1-3 days and reduced to near basal levels 9-11 days thereafter. Proteinuria was nonselective except at very low doses (0.1 mg OX7) where microalbuminuria was seen. F(ab')2 OX7 administration also caused proteinuria in T16 mice. One milligram F(ab')1 OX7 caused diffuse foot process swelling without manifest proteinuria in T16 mice. Anti-Thy 1.1 IgM monoclonal antibody did not produce the effects of OX7 in T16 mice. Foot process swelling was not modified by histamine or 5-hydroxytryptamine antagonists. OX7 did not cause complement activation or leucocyte infiltration, hence glomerular injury appeared to be mediated directly by the antibody.     

Immunohistochemically visualized localisation of gangliosides Glac2 (GD3) and Gtri2 (GD2) in cells of human intracranial tumors.

Antibodies against two major gangliosides detected in human brain and brain tumors--Glac2 (GD3) and Gtri2 (GD2)--were tested by immunohistochemistry in an unselected sample of intracranial tumors during the years 1986 through 1991. Two groups emerged as evaluable samples, namely gliomas of different grades and meningiomas. In a pilot series, it was shown that these gangliosides could be visualized in frozen sections of cells of gliomas and meningiomas (as well as neurinomas) and in some structures of the normal brain. It was however not possible in frozen sections to further analyze the cellular or subcellular expression pattern of the mentioned components and paraffin sections with conventional processing were only weakly and diffusely stained. A modified protocol therefore was created that replaced alcohol processing by acetone. With this protocol, interpretable results in paraffin sections were obtained. With this method, 133 single intracranial tumors were investigated as to their immunohistologically detectable ganglioside expression. The most consistent result was that the whole cytoplasm of highly fibrillary (gemistocytic) astrocytes in all grades of gliomas was stained by Gtri2 (GD2) and Glac2 (GD3) with high preponderance of Gtri2 (GD2) expression. In all meningiomas, Glac2 (GD3) had a higher expression than Gtri2. No constant pattern in the other entities emerged. By comparison with GFAP expression in gliomas and vimentin in meningiomas, the colocalisation of gangliosides and intermediary filament proteins is supposed.     

Antibody and clinical responses in volunteers to immunization with malaria peptide-diptheria toxoid conjugates.

Twenty residue peptides from the 185-200-kD and 45-kD merozoite surface antigens of the malaria parasite Plasmodium falciparum were covalently linked to diphtheria toxoid as a carrier and used to immunize human volunteers with aluminium hydroxide as an adjuvant. Significant antibody levels were elicited by two boosting injections. The antibodies reacted with acetone-methanol fixed merozoite membranes in an immunofluorescence assay, but no inhibition of merozoite reinvasion could be detected in in vitro cultures containing the antibodies. Antibody levels against the immunizing peptides declined markedly within 77 days after the third injection. No hypersensitivity was observed against the peptides. However, the volunteers developed hypersensitivity against diphteria toxoid, and in particular a pronounced type III (Arthus) hypersensitivity after three injections with the toxoid. This effect might appear to limit the use of peptide-diphtheria toxoid conjugates for human immunization. Several biochemical, haematological and immunological tests done on the volunteers showed no other adverse effects from the immunizations.     

Cholera toxin, ganglioside receptors and the immune response.

Cholera toxin activates plasma membrane adenylate cyclase in all mammalian cell types. The structure-function relationship of the toxin has recently been clarified, and the cell membrane receptor identified. This information has made cholera toxin the "agent of choice" for studies in many biological systems of the possible regulatory role of adenylate cyclase/cyclic AMP. This article describes briefly our current knowledge about the toxin and its receptor. It then reviews recent research which has revealed that cholera toxin has strong modulating influences on the proliferation of normal and malignant lympocytes as well as on the initiation and expression of immune responses. The toxin has been found to inhibit DNA synthesis of B and T lymphocytes in vitro without inducing cell death and also to inhibit seems to decrease antibody secretion from plasma cells in vitro, and might also interfere with the release of other soluble immunological mediator subtances. In vivo cholera toxin induces a transient involution of the spleen and a more prolonged lymphocyte depletion of the thymus in mice; these effects appear to be mediated through the adrenal glands. The toxin inhibitors allograft rejection, and either stimulates or suppresses antibody formation depending on the timing of the toxin in relation to the antigen administration. It increases the capacity of the spleen cells to induce graft-vs-host reactions and the "allogeneic effect" on antibody production. An inhibitory effect on a normal suppressor population among the spleen cells has been identified. The findings illustrate the complex effects induced on the immune system by the probably most discriminative investigative tool available for stimulation of the adenylate cyclase/cyclic AMP system.     

Antibody response of the mouse reservoir of Borrelia burgdorferi in nature.

To determine whether the white-footed mouse reservoir host (Peromyscus leucopus) of the agent of Lyme disease (Borrelia burgdorferi) naturally mounts an immune response against the full range of antigens expressed by this zoonotic pathogen, we analyzed the pattern of immunoreactivity of these rodents at sites in which the intensity of transmission differs. Although the incidence of seroconversion within the reservoir population relates proportionally to the density of subadult deer ticks (Ixodes dammini), seroprevalence appears constant. About a fifth as many juvenile mice recognize spirachete antigens as do adult mice. Virtually all reservoir mice in nature recognize the p20, p35.5, p39, and p58 antigens, regardless of the intensity of transmission. Seropositive mice retain reactivity to a wide range of spirochetal antigens. Few mice recognize flagellin, OspB, and OspC. Although a third of serum samples include reactivity to a 31-kDa band, this reaction is irregular and may represent an uncharacterized antigen that comigrates with OspA. Mice captured where transmission is intense recognize the same spectrum of antigens as do mice captured where vector ticks are scarce.     

Block copolymer of poly(ester amide) and polyesters: synthesis, characterization, and in vitro cellular response

In order to expand the properties and applications of aliphatic absorbable polyesters, a new biodegradable block copolymer family, poly(ester amide)-b-poly(ε-caprolactone) (PEA-b-PCL), was synthesized and characterized. These copolymers were synthesized by first preparing l-phenylalanine-based poly(ester amide) macroinitiators (Phe-PEAs) with free amine end groups via a solution polycondensation. The amine-terminated Phe-PEA macroinitiators were then used to initiate the ring-opening polymerization of ε-caprolactone monomer to prepare the PEA-b-PCL copolymers. The molecular weight (MW) of PEA-b-PCLs can be well controlled by adjusting the Phe-PEA MW and weight ratio of ε-caprolactone to Phe-PEA, and ranged from 7 to 50kgmol(-1). The copolymers' structure and properties were characterized by various physicochemical methods, such as nuclear magnetic resonance, gel permeation chromatography and solubility testing. The in vitro enzymatic biodegradation tests were performed to evaluate the biodegradation rate of the copolymers. The results showed that the introduction of Phe-PEA to PCL did not significantly change the degradation rate of PCL. Biological studies were conducted to assess the polymer's biological properties, like supporting the cell attachment and proliferation, and inflammation response. The results showed that the bovine aortic endothelial cells had very good attachment and proliferation performance on PEA-b-PCL coating surface. TNF-α release profiles showed that PEA-b-PCL exhibited a muted J774 macrophage inflammatory response.     

Antibody response to the negative regulatory factor (nef) in experimentally infected macaques: correlation with viremia, disease progression, and seroconversion to structural viral proteins.

The antibody response to structural and regulatory viral proteins was studied in 14 rhesus (Macaca mulatta) and 6 cynomolgus (Macaca fascicularis) macaques experimentally infected with HIV-2 or SIVMAC. To investigate the humoral antibody response to the negative regulatory factor (nef), the recombinant protein was expressed to high levels with recombinant vaccinia virus (VV). nef-specific antibodies were detected in 14 of 20 infected macaques (70%). In sera of all infected monkeys antibodies directed to the structural proteins gp120, p56, and p24 appeared 2 to 6 weeks postinfection. In contrast, the extent and the appearance of nef-specific antibodies during the course of infection varied considerably between individual animals. However, only in sera of four animals (20%) were nef-specific antibodies detectable as early as those against the core proteins p24 and p56. In SIVMAC-infected rhesus macaques at different clinical stages, the antibody response towards nef neither correlated with the development of viral latency nor to disease progression or viremia. Our data indicate that in macaques experimentally infected with SIV or HIV-2 antibody formation against nef is not a useful diagnostic marker either for early detection of viral infection or of disease progression.