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F Chiodi

Publications and source records attributed to F Chiodi.

At least 73 records · Page 4Linked to original sources
PubMed1989

Site-directed enzyme-linked immunosorbent assay with a synthetic simian immunodeficiency virus SIVmac peptide identifying antibodies against the HIV-2 transmembrane glycoprotein.

A 23-amino-acid-long peptide (AIEKYLEDQAQLNAWGCAFRQVC) representing the transmembranous protein gp32 in SIVmac was used in site-directed enzyme-linked immunosorbent assay (ELISA) for detection of HIV-2-specific antibodies in 567 sera from Bissau, Guinea Bissau. Ninety out of the 567 sera were identified to contain HIV-2 antibodies by whole antigen ELISA and Western blot assays. The peptide ELISA correctly identified 89 out of these 90 seropositives (sensitivity 98.9%). Three sera falsely interpreted to be positive were encountered (specificity 99.4%). The HIV-2 peptide was also used for testing of 93 HIV-1-positive Swedish sera. None of these sera reacted. Site-directed serology employing synthetic peptides should be considered for application as a screening assay.

Blotting, Western↗
PubMed1989

Analysis of a subclass-restricted HIV-1 gp41 epitope by omission peptides.

To define the amino acids involved in IgG subclass reactivity to two overlapping HIV-1 gp41 (E34/32; amino acid positions 582-613) peptides, sera from 18 HIV-infected individuals were studied. Peptides mimicking E34 but with single amino acid deletions or glycine substitutions were used to define the amino acid residues necessary for antibody binding. Two dominating immunogenic epitopes, containing highly hydrophilic amino acids, were found on the original peptide. Further analysis was undertaken with two corresponding omission sets of dodecapeptides representing halves of the complete E34 plus a terminal cystein peptide. The subclass reactivities usually differed between the patients with regard to the epitopes with which the different IgG subclasses reacted and also to the importance of different amino acids in antibody binding. The 600 glycine and the 601 lysine were involved in the binding of all IgG1, 2 and 4 and most IgG3. The development of E34/32-reactive IgM and IgG subclasses showed different patterns in four patients with primary HIV infections, contradicting the existence of a general pattern for the development of IgG subclasses to this peptide. The findings suggest that different progenitor clones are selected for synthesis of the different subclasses.

Amino Acid Sequence↗
PubMed1988

Lack of cross-reaction in antibody-dependent cellular cytotoxicity between human immunodeficiency virus (HIV) and HIV-related West African strains.

Sera from individuals infected with human immunodeficiency virus (HIV) and HIV-related West African viruses can mediate high-titered, virus-specific antibody-dependent cellular cytotoxicity (ADCC) in all stages of infection. No cross-reactive ADCC can be detected between HIV and HIV-related West African strains LAV-2, HTLV-IV, and SBL-6669. Because these two groups of viruses have antigenically distinct envelope glycoproteins, ADCC-mediating antibodies are most likely directed against envelope antigens. For HIV-specific ADCC, this was further confirmed by using sera reacting with HIV envelope but negative for antibodies against viral core antigens.

Africa, Western↗
PubMed1988

Accentuated antibody response to paramyxoviruses in individuals infected with human immunodeficiency virus.

Sera from 31 human immunodeficiency virus (HIV)-infected patients, representing different clinical stages of HIV infection, were assayed for antibodies against measles and mumps viruses by various serological tests and compared to 23 healthy controls. Sera from four patients (two primary, one asymptomatic, and one acquired immunodeficiency syndrome) exhibited a pronounced antibody response to measles as detected by haemagglutination inhibition and radioimmuno-precipitation assay. The RIPA-positive sera showed increased reactivity to all the viral components and in particular to the haemagglutinin (HA) protein of the virus (Fig. 1). Three of these positive patients also showed a similar response to mumps virus. One of the control sera also showed an increase in antibody titre in measles serological tests. The measles antibodies were shown not be anti-HIV antibodies crossreacting with paramyxoviruses. The reactivity to haemagglutinin was still present when using nonglycosylated measles virus antigen grown in the presence of tunicamycin. Whether the accentuated antibody response is due to polyclonal activation mediated by HIV or to reactivation of the viruses remains to be answered.

AIDS-Related Complex↗
PubMed1988

Human immunodeficiency virus infection of the brain. II. Detection of intrathecally synthesized antibodies by enzyme linked immunosorbent assay and imprint immunofixation.

Sera and CSF from 29 patients in early and late stages of HIV infection were analysed for intrathecal antibody production. Elevated CSF-IgG indices indicating intrathecal IgG synthesis were demonstrated in 9 patients while 4 of 18 patients tested had oligoclonal IgG bands in the CSF. Analysis of HIV-specific antibodies by enzyme-linked immunosorbent assay (whole antigen and site-directed ELISA) and calculation of "antibody indices" (CSF/serum antibody quotient divided by CSF/serum albumin quotient) indicated intrathecal HIV antibody synthesis in 19 patients. Analysis of serum and CSF antibodies by an imprint immunofixation (IIF) method showed intrathecal synthesis of predominantly polyclonal HIV-IgG antibodies in 11 of 13 patients examined. IIF analysis of antibodies to six other infectious agents showed no intrathecal antibody production except in one patient who had minor fractions of intrathecally synthesized IgG antibodies to varicella zoster virus. The present results demonstrate that an intrathecal HIV-specific antibody response may be present in both early and late stages of HIV infection, and indicates that HIV may reach the brain at an early stage of infection.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Human immunodeficiency virus infection of the brain. I. Virus isolation and detection of HIV specific antibodies in the cerebrospinal fluid of patients with varying clinical conditions.

Isolation of the human immunodeficiency virus (HIV) has been attempted from the cerebrospinal fluid (CSF) of 29 subjects with varying severity of HIV infection. Virus could be isolated from patients in all stages of disease including patients with primary HIV infection and asymptomatic carriers. In the early stages of infection free virus was infrequently present in the CSF but could be isolated from the cells present in CSF. This suggests that HIV may reach the brain at a very early stage of infection and that initially there is little production of virus from infected cells. In the late stages of HIV infection, associated with increasing severity of immunodeficiency, free virus could readily be isolated from the CSF. With one exception, all of these patients had neurological and/or psychiatric symptoms, as compared to only 2 (of 13) subjects in the early stages of infection. All patients with HIV-specific antibodies in serum had antibodies also in CSF. Examined by a radioimmunoprecipitation assay, CSF was more often found to contain antibodies to the precursor (p55) of viral core proteins than the corresponding serum of the patients. We propose that immune disturbances have an essential pathogenic role in the neurological/psychiatric symptoms associated with HIV infection, possibly through allowing increased viral expression in the central nervous system.

AIDS-Related Complex↗
PubMed1988

Guillain-Barré syndrome in chronic alcoholism.

This report describes six cases of chronic alcoholics affected by Guillain-Barré syndrome. The syndrome was the main clinical feature recorded in the patients. The possibility that alcohol abuse may have relevance in the pathogenesis of the Guillain-Barré syndrome is discussed.

Adult↗
PubMed1988

B and T cell reactivities after immunization of macaques with HIV subcomponents.

A model system was established for studies of humoral and cellular immunity to human immunodeficiency virus (HIV) antigens after vaccination. Macaques (Macaca fascicularis) were immunized with purified HIV, an infected cell extract rich in gp120 or polypeptides of cloned genes representing parts of p24, gp41, and gp120. Western blot analysis best showed the appearance of antibodies to nucleocapsid proteins, and antibodies to higher molecular weight envelope glycoproteins were better demonstrated by radioimmunoprecipitation. With whole HIV, antibodies to p24 appeared first, and sometimes were the only ones to be demonstrable. Several immunizations with HIV or recombinant polypeptides were required to obtain antibodies to gp120, and the responses were weak. Although the envelope-specific response was weak, this was the only component that mediated neutralizing capacity. Escherichia coli-derived viral transmembrane polypeptide (g)p41 also had a poor immunizing effect. IgG synthesis from B cells in vitro was demonstrable to antigens and generally paralleled the antibody titers of sera after multiple immunizations. The HIV-specific lymphocyte proliferation response as measured by DNA synthesis was best seen with polypeptide p24-15, followed by the other antigens.

Animals↗
PubMed1988

Isolation frequency of human immunodeficiency virus from cerebrospinal fluid and blood of patients with varying severity of HIV infection.

Isolation of the human immunodeficiency virus (HIV) has been attempted from the cerebrospinal fluid (CSF) of 63 subjects at different stages of HIV infection, including asymptomatic carriers and patients with or without neurologic or psychiatric complications. In addition blood was collected from 40 of these subjects for virus isolation. HIV could be isolated from the CSF at all clinical stages with an overall frequency of 40%. In contrast, the frequency of HIV isolation from the blood was lower (32%) at the early stages of infection than in patients with severe disease (77%). HIV isolation from the CSF was more frequently positive in patients with neurologic or psychiatric complications than in patients showing no such disturbances (48 and 32%, respectively).

Acquired Immunodeficiency Syndrome↗
PubMed1988

Distinct replicative and cytopathic characteristics of human immunodeficiency virus isolates.

According to their capacity to replicate in vitro, human immunodeficiency virus (HIV) isolates can be divided into two major groups, rapid/high and slow/low. Rapid/high viruses can easily be transmitted to a variety of cell lines of T-lymphoid (CEM, H9, and Jurkat) and monocytoid (U937) origin. In contrast, slow/low viruses replicate transiently, if at all, in these cell lines. Except for a few isolates, the great majority of slow/low viruses replicate in peripheral blood mononuclear cells and Jurkat-tatIII cells constitutively expressing the tatIII gene of HIV-1. The viruses able to replicate efficiently cause syncytium formation and are regularly isolated from immunodeficient patients. Poorly replicating HIV isolates, often obtained from individuals with no or mild disease, show syncytium formation and single-cell killing simultaneously or, with some isolates, cell killing only.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Antibody response in primary human immunodeficiency virus infection.

The antibody response in 20 homosexual men with symptomatic primary HIV infection was studied with ten different antibody assays (enzyme-linked immunosorbent assays, indirect immunofluorescence assays, radioimmunoprecipitation [RIPA], and western blot). HIV antibodies were detectable by all the assays within 2 months after onset of illness. RIPA and western blot were more sensitive than the other assays--all serum samples obtained at 2 weeks and after were reactive. In all cases, the first serum sample reactive by RIPA precipitated gp160 whereas, by western blot, antibodies to p24 were first recognised. This study shows the necessity of including gp160 and p24 in any assay to detect early antibody response in primary HIV infection. 5 patients were studied by virus isolation. During the 2 first weeks after onset of symptoms, HIV was demonstrated in cell-free plasma in all cases and, in 4 cases, also in peripheral blood mononuclear cells. Samples obtained later contained demonstrable infectious virus in only 1 of 4 cases. Thus a phase of viraemia precedes the antibody response in symptomatic primary HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Site-directed ELISA with synthetic peptides representing the HIV transmembrane glycoprotein.

Two partially overlapping 19 and 22 amino acids long peptides representing a highly immunogenic site of the transmembranous glycoprotein (gp41) of human immunodeficiency virus (HIV) were used as antigen in ELISA tests. The results of antibody determination with this assay were compared with those of three or more conventional ELISAs and Western blot (WB) tests and radioimmunoprecipitation assay. Twenty-six sera from patients with AIDS or LAS and from asymptomatic carriers of HIV infection all showed a pronounced reaction in the peptide ELISA as well as positive results with other tests. In contrast, 27 sera from laboratory workers and blood donors were negative by all tests. A group of 39 blood donor sera, which had shown false positive or ambiguous results in the ELISAs and sometimes in WB tests employed for confirmation, also were negative in all cases with the peptide ELISA. Consecutive samples collected from individuals with primary HIV infection were also analyzed. In 6 out of 9 cases, the peptide ELISA revealed an antibody response within one month after onset of clinical symptoms and sensitivity for antibody detection equaled that of other ELISA tests. Eight sera from five West African persons infected with HIV-related viruses did not react in the peptide ELISA, reflecting differences in properties of the envelope components. The peptide ELISA used in this study appears to represent a simple technique employing chemically synthesized antigen for accurate and sensitive estimation of antibodies to the HIV group of nontransforming human retroviruses.

AIDS-Related Complex↗
PubMed1987

Isolation of human immunodeficiency virus (HIV) from plasma during primary HIV infection.

Human immunodeficiency virus (HIV) has been isolated from plasma in 6 of 7 patients showing clinical symptoms of a primary HIV infection. Parallel cultures from peripheral blood mononuclear cells (PBMC) yielded virus in 5 patients. In one case, virus could only be isolated from the cerebrospinal fluid but not from peripheral blood. Detectable viremia was transient and preceded the appearance of HIV specific antibodies. After cessation of acute symptoms, the frequency of HIV isolations was similar to that of asymptomatic carriers (23 and 26%, respectively). The role of the immune response in terminating detectable viremia remains to be established.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Detecting immunoglobulin abnormalities in the cerebrospinal fluid (CSF): which methods are best for clinical purposes?

Several techniques are now available for the quantitative and qualitative examination of CSF proteins modified during the course of neurological disease. The CSF and serum of 42 patients suffering from various neurological diseases and of 7 controls were examined using quantitative methods--single radial immunodiffusion, nephelometric analysis--and qualitative methods--isoelectric focusing on polyacrylamide gel and on agarose gel, isoelectric focusing of unconcentrated CSF followed by transfer to cellulose nitrate membranes and immunoperoxidase staining and double antibody peroxidase labeling and avidin-biotin amplification. In the present study the results and the advantages of different methods are described and compared.

Evaluation Studies as Topic↗
PubMed1987

Radioimmunoprecipitation and Western blotting with sera of human immunodeficiency virus infected patients: a comparative study.

The sensitivity and specificity of radioimmunoprecipitation assay (RIPA) and Western blot (WB) test were compared by use of a collection of 183 sera, representing different categories of individuals, noninfected or infected with the human immunodeficiency virus (HIV). The sera were subdivided on the basis of their reactivity in at least two anti-HIV enzyme-linked immunosorbent assays (ELISA); 53 sera were negative and 61 sera were positive in both tests, whereas 69 sera showed ambiguous reactions. The reaction patterns in RIPA could be divided into 6 different groups. The same grouping could to some extent be applied to the results of WB test. RIPA provided the most efficient means for identification of the large viral envelope glycoproteins, gp120/160, whereas gp41 was detected more effectively by WB. Internal virus components reacted to a varying extent with specific antibodies in the two tests. The reaction with pol products was more pronounced with the WB tests in which extracellular material was used as antigen. In a few WB tests, however, the reaction with internal components did not reflect a prior HIV infection. No such ambiguity was observed with RIPA, reflecting the advantage of a test that uses a minimally denaturated antigen and provides appropriate conditions for identification of the large viral glycoproteins. The practical choice of confirmatory tests to be used in diagnostic laboratories requires evaluation of both the sensitivity and specificity of the tests but also their economy and convenience.

Acquired Immunodeficiency Syndrome↗
PubMed1987

A new human retrovirus isolate of West African origin (SBL-6669) and its relationship to HTLV-IV, LAV-II, and HTLV-IIIB.

A new human retrovirus of West African origin (SBL-6669) has been isolated from a patient with immunological and clinical signs of immunodeficiency. Using radioimmunoprecipitation assays (RIPA) and Western blot (WB) tests with human sera, the new virus isolate has been compared with HTLV-IV, LAV-II, and the HTLV-IIIB prototype strain of the human immunodeficiency virus (HIV). The West African isolates appeared to be members of the same virus group since their glycoproteins were antigenically indistinguishable. West African sera showed no detectable cross reaction with HTLV-IIIB glycoproteins. The external glycoprotein in the different virus strains only showed minor variations in size. The size of the transmembranous protein was not unambiguously defined. In the West African virus isolates a 30-35 kD protein was seen similar to the protein previously described possibly to represent this component. However, in SBL-6669 a distinct 41 kD protein was also identified. There were interstrain variations in the size of several viral proteins among the West African virus isolates. Only minor differences were seen between SBL-6669 and LAV-II. The variations were most pronounced in two core proteins corresponding to the 19 kD and 24 kD proteins of HTLV-IIIB. In addition, West African human retroviruses appear to differ in pathogenicity. LAV-II and SBL-6669 are associated with immunodeficiency, whereas HTLV-IV was isolated from healthy individuals. Since further spread of these viruses to other parts of the world is imminent, it is necessary to consider their antigenic and immunogenic properties in serodiagnosis of HIV infections and in planning for immunoprophylactic interventions.

Antigens, Viral↗