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P Putkonen

Publications and source records attributed to P Putkonen.

At least 37 records · Page 2Linked to original sources
PubMed1994

Stable biological and antigenic characteristics of HIV-2SBL6669 in nonpathogenic infection of macaques.

The purpose of the present study was to investigate if the biological and antigenic properties of human immunodeficiency virus type 2 change over time in cynomolgus macaques (Macaca fascicularis) experimentally infected with HIV-2SBL6669. Sequential virus isolates and serum samples were obtained during a 2-year period and studied in autologous neutralization assays. All six macaques studied seroconverted shortly after infection and remained healthy during the observation period. Virus could be isolated from all six animals during the first 100 days postinfection. Thereafter four monkeys became virus isolation negative, either permanently or transiently (two macaques each), whereas two macaques remained virus isolation positive during the entire observation period. Sequential reisolates from the macaques invariably replicated in HUT-78, U937-2, and Jurkat-tat cell lines, similarly to the HIV-2SBL6669 inoculum virus. The ability to produce neutralizing antibodies correlated with positive virus isolations, hence four macaques produced neutralizing antibodies against inoculum virus and sequential reisolates. Once the neutralizing antibody appeared, sequential reisolates obtained at both early and late time after infection were neutralized, indicating that the neutralizing epitopes of the virus are conserved in the infected animals over time. This is different from the pathogenic SIVsm infection in macaques or HIV-1 infection in humans, where emergence of neutralization resistant variants seems to be the rule. In contrast, in HIV-2-infected macaques the biological properties of the virus are stable and the neutralizing antibody response shows extensive cross-reactivity.

Animals↗
PubMed1994

Broadly reactive HIV-2 and SIVmac specific antibody-dependent cellular cytotoxicity in immunized and infected cynomolgus monkeys.

Antibody-dependent cellular cytotoxicity (ADCC) was analysed in groups of cynomolgus monkeys that had been immunized with either HIV-2 (strains SBL6669 or SBL-K135) or SIVmac. HIV-2- and SIVmac-infected monkeys were also studied for ADCC. Sequential serum samples were collected from the animals, which were followed for 1 to 3 years. Sera from the HIV-2-immunized monkeys had ADCC against both homologous and heterologous HIV-2 strains as well as cross-reactivity against SIVmac-infected target cells. This broadly reactive ADCC response could be detected within the first weeks after immunization. Homologous ADCC was also seen in seven of eight SIVmac-immunized monkeys which were all protected from later challenge with SIVmac or SVsm. ADCC titres sometimes decreased after a few months if the immunized monkeys were not boosted whereas most of the HIV-2-and SIVmac-infected monkeys developed a rapid and persistent ADCC response. The presence of ADCC, like the presence of neutralization in previous studies, did not predict whether the immunized monkeys would be protected upon challenge with live virus.

AIDS Vaccines↗
PubMed1994

Long-standing protection of macaques against cell-free HIV-2 with a HIV-2 iscom vaccine.

We investigated the capacity of two immunostimulating-complex (iscom) formulations including inactivated native HIV-2 viral proteins and selected peptides to induce protective immunity against HIV-2 in a nonhuman primate. Four cynomolgus monkeys were first immunized with five i.m. injections of purified detergent-disrupted HIV-2 virions (total dose, 0.7 mg) in iscoms over a period of 16 months. At months 18 and 20, all four macaques were given booster immunizations with iscom-coupled V3-derived synthetic peptides representing a dominating neutralizing region of HIV-2 gp125. Two weeks after the final dose of vaccine, the four vaccinated animals, together with four controls, were challenged i.v. with 10 monkey infectious doses (MID50) of monkey-cell-grown homologous cell-free virus, HIV-2SBL-6669/H5. After the challenge, the four control animals became readily infected; however, three of four vaccinated animals were protected as shown by repeated negative virus isolations and negative polymerase chain reaction for viral DNA and by failure to transmit HIV-2 infection with whole blood and lymph node cells into naive cynomolgus macaques. One of three protected animals showed an anamnestic antibody response to a dominating antigenic site, indicating possible limited virus replication. The vaccine-protected monkeys were subsequently resistant to rechallenge infection at 12, 15, and 18 months after the first challenge, suggesting that a reasonable duration of protective immunity had been induced by the vaccine.

AIDS Vaccines↗
PubMed1993

Expression of Epstein-Barr-virus-related nuclear antigens and B-cell markers in lymphomas of SIV-immunosuppressed monkeys.

Simian-immunodeficiency-virus(SIV)-infected cynomolgus monkeys develop B-cell lymphomas in approximately one third of the cases. We have now studied the expression of cynomolgus-Epstein-Barr-virus(cyno-EBV) nuclear antigens in 13 cyno-EBV-carrying SIVsm-associated monkey lymphomas and established cell lines from 3 of these tumors. Immunoblots of cell lysates were probed with polyspecific and monospecific reagents directed against human EB-virus EBNAI-6, and against the membrane protein LMPI. An EBNA2-cross-reacting protein was demonstrated in 8 lymphoma tissues (8/13) and in the 3 cell lines derived from the tumors. All tumors expressed a polypeptide with 50 to 55 kDa molecular weight, which cross-reacted with some antibodies to EBNAI. Absorption experiments with normal monkey tissue showed that this polypeptide was specific for the cyno-EBV-carrying lymphoma cells. Equivalents of EBNA3-6 and LMPI could not be detected. Immunophenotypical characterization showed that the monkey lymphomas were similar to human HIV-associated B-cell lymphomas. Malignant B-cell lymphomas in experimentally SIVsm-infected cynomolgus monkeys can be a model for EBV-associated lymphomagenesis in immunodeficiency states.

Animals↗
PubMed1993

Autologous neutralizing antibodies to SIVsm in cynomolgus monkeys correlate to prognosis.

Sequential virus isolates from eight cynomolgus monkeys experimentally infected with SIVsm were studied for susceptibility to neutralization by autologous antibodies. The biological and antigenic characteristics of sequential reisolates differed both from the inoculum virus and from each other. Five monkeys developed neutralizing antibodies to the inoculum virus and the 12-day reisolate at 4 months postinfection, while the remaining three monkeys produced very little, if any, neutralizing antibodies. Strikingly, the two long survivor monkeys developed neutralizing antibody response to a second or third autologous reisolate and to 12 reisolates obtained from other monkeys. Thus the neutralizing antibody response of the long survivor monkeys showed a relatively broad specificity, whereas the neutralizing antibody response of the monkeys with early disease, if at all present, was specific for the infecting strain only and lost over time. Our results show that the pattern of virus neutralization in SIVsm-infected monkeys is similar to human immunodeficiency virus type 1-infected humans. In both cases, variant viruses resistant to neutralization by autologous sera emerge during the entire course of infection. In addition, the ability to produce autologous neutralizing antibodies to sequential virus reisolates appeared to correlate with the degree of immunodeficiency in the host.

Animals↗
PubMed1993

Protection of cynomolgus macaques (Macaca fascicularis) against infection with the human immunodeficiency virus type 2 strain ben (HIV-2ben) by immunization with the virion-derived envelope glycoprotein gp130.

We have investigated the efficiency of a subunit vaccine consisting of native gp130 micelles of HIV-2ben mixed with keyhole limpet hemocyanin (KLH). Over a period of 52 weeks, nine cynomolgus monkeys (Macaca fascicularis) were immunized with seven intramuscular injections of gp130-KLH, equivalent to a total of about 1.1 mg of purified gp130 per animal. The first three applications were formulated in Freund's incomplete adjuvant. Because of the effects of Freund's incomplete adjuvant, aluminum hydroxide was used for the four subsequent immunizations. Each of the nine vaccinated animals along with six controls were challenged with 10 monkey infectious doses (MID50) of live HIV-2ben. At the time of challenge, the vaccinees had developed anti-gp130 titers ranging from 1 to 1.5 x 10(5). Four animals exhibited neutralizing antibodies. After iv challenge with 10 MID50 of HIV-2ben the nine vaccinees showed neither a secondary immune response nor a transient viremia. However, in four of the nine immunized animals proviral sequences were sporadically detected by polymerase chain reaction (PCR) and one of these four animals developed cytotoxic T lymphocytes. All six control animals developed a primary antibody response to HIV-2ben and became PCR positive. Four animals showed cytotoxic T cell activity and two developed a transient viremia. The five vaccinees with no sign of virus infection were reimmunized once and challenged with 10 MID50 of the heterologous virus HIV-2SBL-6999. Four weeks later all animals were PCR positive. A naive control animal and four of the vaccinees showed primary or secondary antibody responses and transient viremia. One of the revaccinated animals did not become viremic, and viral antibodies did not increase.

AIDS Vaccines↗
PubMed1993

Identification of four antibody-binding sites in the envelope proteins of simian immunodeficiency virus, SIVsm.

OBJECTIVE: To identify antigenic regions in the envelope glycoproteins of the simian immunodeficiency virus isolate, SIVsm. METHODS: Thirty-eight peptides were synthesized and used in site-directed enzyme-linked immunosorbent assays with sera from experimentally infected macaques. RESULTS: Four antibody-binding regions were identified, corresponding to the second variable region [V2; amino acids (aa) 170-196], the region homologous to V3 in HIV-1 (aa 313-346), the carboxy terminus of gp120 (aa 514-537) and the amino terminus of the transmembrane protein (aa 608-638). Serum reactivity to the V2 region was higher in surviving monkeys than in animals with an early development of simian AIDS. The antigenicity of the peptide appears to be conformationally dependent. CONCLUSIONS: The majority of antigenic sites identified in the envelope proteins of SIV correspond to sites identified in HIV-1 and HIV-2, which further supports the use of the simian model in vaccine development. The pattern of reactivity to the V2 region suggests that absence of antibodies directed to this site might correlate with disease progression.

Amino Acid Sequence↗
PubMed1992

A monkey model for Epstein Barr virus-associated lymphomagenesis in human acquired immunodeficiency syndrome.

High-grade malignant nonHodgkin's lymphomas--five lymphoblastic, three pleomorphic, and two immunoblastic--developed in 10/25 cynomolgus monkeys (Macaca fascicularis) followed for up to 746 d after infection with simian immunodeficiency virus, strain SIVsm. These lymphomas were shown to be associated with an Epstein-Barr (EB)-like cynomolgus B-lymphotropic herpesvirus (CBLV) by electron microscopy, by Southern blot hybridization with probes against human EBV, and by the expression of antigens corresponding to EBV-associated nuclear antigens (EBNAs) involved in human B cells transformation. Southern blot demonstration of immunoglobulin gene rearrangements and homogeneous EBV episomes indicated that all the lymphomas were CBLV-associated monoclonal B cell proliferations. Our findings suggest that these tumors correspond to the EBV-associated malignant lymphomas in acquired immunodeficiency syndrome with respect to clinical, morphological, phenotypic, and genotypic characteristics. The particular susceptibility of SIVsm immunodeficient cynomolgus monkeys for CBLV-associated lymphomagenesis appears therefore a useful model for EBV-associated lymphomas in humans.

Animals↗
PubMed1992

Prevention of HIV-2 and SIV infections in cynomolgus macaques by prophylactic treatment with 3'-fluorothymidine.

The aim of this study was to determine the usefulness of human immunodeficiency virus type 2 (HIV-2) for in vivo evaluation of antiviral drugs in monkeys and to study if prophylactic treatment with 3'-fluorothymidine (FLT) could prevent infection against a low challenge dose of HIV-2 or simian immunodeficiency virus (SIV). Protection against infection was assessed by virus isolation and polymerase chain reaction (PCR) on monkey peripheral blood mononuclear cells (PBMC) as well as by antibody and viral antigen assays. Prophylactic treatment with FLT 3 x 5 mg/kg/day, starting 8 h prior to virus inoculation, prevented HIV-2 infection in 3 of 8 monkeys. In another experiment 2 of 4 monkeys resisted 2-10 monkey infectious doses (MID50) of SIV with the same prophylactic treatment. All control animals (HIV-2 n = 8, SIV n = 4) became infected. Thus, FLT treatment prevented HIV-2 and SIV infection in 5 of 12 animals.

Animals↗
PubMed1992

Prevention of HIV-2 and SIVSM infection in cynomolgus monkeys by active or passive immunization.

We have established experimental infection with HIV-2 and SIVsm in cynomolgus monkeys and successfully used these models for vaccine experiments. Protection against homologous HIV-2 infection was demonstrated in two of two monkeys immunized with a Triton-X100-treated whole HIV-2SBL-6669 vaccine in incomplete Freund's adjuvant and in 2 of 4 monkeys immunized with a formalin-inactivated whole HIV-2 vaccine in RIBI adjuvant. Monkeys preinfected with a live poorly replicating HIV-2 strain were shown to develop cross-protection against SIV-induced disease. We have shown also that HIV-2 and SIVsm infection in cynomolgus monkeys can be prevented by passive immunization. These results raise hope for effective immunization against HIV infections in humans.

AIDS Vaccines↗
PubMed1992

Malignant lymphoma associated with human AIDS and with SIV-induced immunodeficiency in macaques.

Malignant lymphomas associated with human (HIV) and simian (SIV) immunodeficiency virus infections are reviewed and compared. Recent observation of a high frequency of lymphomas in a series of cynomolgus macaques, highly immunodeficient after infection with SIVsm(smm3) are described. In addition to the increased frequency in human and monkey AIDS, SIV and HIV lymphomas share several important features. Clinically and by histology they present as aggressive high-grade malignant tumors with a predilection for extranodal growth in viscera, skin, central nervous system, testis, and retroorbitally. Most malignant lymphomas are of B-cell origin. AIDS lymphomas in humans are heterogeneous with regard to Epstein-Barr virus (EBV) association. Similarly, most lymphomas in monkeys experimentally infected with SIV tested to date were shown to be associated with an EBV-like simian herpes virus. These observations point to the possibility of using SIV-immunodeficient macaques for study of EBV and other oncogenic and immunosuppressive factors in AIDS-associated lymphomagenesis.

AIDS-Related Complex↗
PubMed1992

Clinical features and predictive markers of disease progression in cynomolgus monkeys experimentally infected with simian immunodeficiency virus.

OBJECTIVE: To study the pathogenicity of simian immunodeficiency virus (SIVsm) in cynomolgus monkeys in order to establish an animal model for human AIDS. METHODS: Thirty-three cynomolgus monkeys were monitored for more than 2 years following experimental infection with SIVsm. RESULTS: All the macaques became SIV-infected, as demonstrated by virus recovery from peripheral blood lymphocytes and by the appearance of viral antibodies. SIVsm was found to be pathogenic, killing 29 out of the 33 monkeys (88%) within 26 months. Clinically, infected monkeys developed lymphadenopathy, splenomegaly, diarrhoea, weight loss, neurological symptoms and a remarkably high incidence (39%) of malignant lymphomas. All lymphomas were high-grade malignant and of B-cell origin. Disease progression was associated with low CD4+ lymphocyte count, involution of initially hyperplastic follicular B-cell areas in lymph nodes, reappearance of viral antigen in serum, loss of anti-Gag antibodies and development of systemic giant cell disease in 55% of the monkeys. CONCLUSIONS: There are many similarities between SIVsm-induced AIDS in cynomolgus monkeys and human AIDS with regard to clinical, virological, immunological and pathological manifestations.

Acquired Immunodeficiency Syndrome↗
PubMed1992

[Opportunistic malignant lymphomas in SIV infected primates--a model for Epstein-Barr virus associated lymphomas in AIDS].

In a series of 33 cynomolgus monkeys (Macaca fascicularis) experimentally infected with Simian Immunodeficiency virus (SIV), strain smm3, 13 animals developed malignant Non-Hodgkin lymphomas. These lymphomas presented with unusual primary manifestations like in the orbita, testes, and brain. The morphological features and immunophenotyping identified the tumors as high malignant B-cell lymphomas. In all tumors as well as in tumor-derived cell lines a cynomolgus B-lymphotropic herpes virus (CBLV) with structural homogeneity to the Epstein-Barr virus (EBV) could be demonstrated by Southern blotting with EBV-specific probes. The lymphoma cells also expressed CBLV-associated nuclear antigens involved in B-cell transformation crossreacting with EBNA-specific human sera and monoclonal antibodies. Ig-gene rearrangement studies revealed clonal populations, however, no translocations of the c-myc oncogene could be detected. The lymphomas developing with high frequency in SIV-induced immunodeficiency resemble a major subtype of human EBV-associated AIDS lymphomas. This animal model can therefore be used to further elucidate interactions of HIV and EBV in AIDS-related lymphomagenesis.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Identification of B-cell antigenic sites on HIV-2 gp125.

Synthetic peptides were used to identify continuous antigenic sites on the external envelope glycoprotein gp125 of human immunodeficiency virus (HIV)-2. Initially, seven HIV-2-positive human serum samples were screened with 172 sequential nonapeptides containing a six-amino-acid overlap. This represents the entire gp125 molecule of HIV-2ISY. The antibody reactivity was found to be mainly restricted to 14 regions within gp125. Following these results, 33 longer peptides, 15-24 amino acids in length, were synthesized and tested against a larger number of samples. Eleven antigenic regions were thus identified. Two of these were detected within a region corresponding to the C1 region and four others within a region corresponding to the C2 region of HIV-1. The highest frequency of reactivity (90%) of 31 HIV-2 seropositive human serum samples was elicited by three peptides from a region corresponding to the V3 region of HIV-1. The C-terminal portion of this region was recognized by almost 80% of the samples. Reactive regions corresponding to the V4, V5, and N-terminal portion of V4 were also identified. A mouse monoclonal antibody reacting with gp125 was mapped to the N-terminal region of the molecule and was found to react with the sequence DVWNLFETS. The peptides were used to evaluate the antibody response of monkeys immunized with whole killed HIV-2 or simian immunodeficiency virus (SIV). The monkeys showed a pattern of reactivity similar to HIV-2-infected human serum samples. Postinfection samples from monkeys inoculated with HIV-2 or SIV reacted mainly to peptides from the V3 region. Two peptides were used to detect the seroconversion of two SIV-infected monkeys. Thus, we have demonstrated that human seroreactivity to HIV-2 gp125 occurs at a few distinct linear antigenic sites distributed at similar positions on the molecule as those in HIV-1 gp120.

Amino Acid Sequence↗
PubMed1991

Prevention of HIV-2 and SIVsm infection by passive immunization in cynomolgus monkeys.

Infection of macaques with simian immunodeficiency virus (SIV) and human immunodeficiency virus type 2 (HIV-2) are useful models for studies of immunotherapy and vaccination against HIV as well as for testing of antiviral drugs. Vaccine research showing protective immunity in immunized monkeys has indicated that it will be possible to develop a vaccine for prevention of human HIV infection, although many hurdles remain. The design of an HIV vaccine would be helped if the basis of the protective immunity could be elucidated. Passive immune prophylaxis offers a means to determine the relative role of antibodies in protection against infection. We have studied whether a transfer of antibodies can prevent HIV-2 and SIVsm (SIV of sooty mangabey origin) infection in cynomolgus monkeys. Sera with high antibody titres were collected, heat-treated and injected into naive animals 6 h before challenge with 10-100 monkey-infectious doses of live homologous virus. All control animals treated with normal monkey serum (n = 6) or no serum (n = 39) became infected by the challenge virus, whereas five out of seven animals pretreated with antibody-containing serum at a dose of 9 ml kg-1 resisted infection. Thus passively transferred antibodies can protect against a low-dose lentivirus challenge in a nonhuman primate.

Animals↗
PubMed1991

Vaccine protection against HIV-2 infection in cynomolgus monkeys.

The aim of this study was to determine if protection against an infectious human immunodeficiency virus type 2 (HIV-2) challenge could be obtained in cynomolgus macaques by active immunization using whole killed virus vaccine. Four monkeys were immunized with killed HIV-2SBL-6669, two of them with five intramuscular (im) injections of viral preparation containing 100 or 300 micrograms protein emulsified in incomplete Freund's adjuvant (IFA) and the two remaining received four im injections of 25-50 micrograms viral protein in iscoms. Each of the four vaccinated cynomolgus monkeys, along with four unvaccinated controls, were challenged intravenously two weeks after the last booster with approximately 100 animal infectious doses (ID50) of live HIV-2SBL-6669. All four immunized monkeys developed antibodies to HIV-2 envelope and core proteins before challenge exposure to HIV-2, but only the two animals vaccinated with virus in IFA developed detectable neutralizing antibodies. The two monkeys immunized with killed virus in IFA have shown no evidence of infection nine months after challenge with live virus. When blood and lymph node cells from these animals were transfused into naive cynomolgus monkeys, the recipients remained free of infection. In contrast, virus was recovered repeatedly in all nonimmunized animals and in the two animals immunized with iscom-associated viral antigens, which had a low content of envelope gp125 antigen. The demonstration of vaccine-induced protection against HIV-2 in a nonhuman primate raises hope for effective immunization against HIV infections in humans as well.

Animals↗
PubMed1991

Comparison of linear antigenic sites in the envelope proteins of human immunodeficiency virus (HIV) type 2 and type 1.

The occurrence of dominant linear antigenic sites in the envelope glycoproteins of human immunodeficiency virus type 2 (HIV-2) was evaluated. Twenty-five peptides representing different regions of HIV-2, strain SBL-6669, were synthesized. For comparison the corresponding peptides of HIV-1, strain BRU, were also prepared. The peptides were tested in enzyme-linked immunosorbent assay (ELISA) with human sera from individuals with proven HIV-1 or HIV-2 infection and simian sera from animals infected with HIV-2 or simian immunodeficiency virus of sooty mangabay monkey origin (SIVsm). Four major antigenic regions were identified. Peptides representing parts or the whole V3 (neutralizing loop) region and an additional stretch of amino acids located at the carboxy terminal of this region showed considerable reactivity. This reaction was predominantly type specific, but some heterotypic reactivity was also seen. Peptides representing the carboxy terminal 21 amino acids of the V3 region of the type-related viruses HIV-2 and SIVsm allowed selective identification of strain-specific antibodies. A second major antigenic region was found close to the carboxy terminal end of the large glycoproteins. This region was cross-reactive between the two types. The two additional dominating antigenic regions were located in the amino terminal region of the transmembrane glycoprotein. One region has previously been shown to be a uniquely antigenic type-specific site. The other region was also type-specific, but was identified only in HIV-2, amino acids Glu634-Lys649. Excellent facilities are available for the design of not only type-unique site-specific serological tests but potentially also type-cross-reactive and strain-specific assays.

Animals↗