Construction, replication, and immunogenic properties of a simian immunodeficiency virus expressing interleukin-2

To study the effect of interleukin-2 (IL-2) on simian immunodeficiency virus (SIV) replication, pathogenesis, and immunogenicity, we replaced the nef gene of SIVmac239 by the IL-2 coding region. The virus, designated SIV-IL2, stably expressed high levels of IL-2 in cell culture. In comparison to SIVmac239, SIV-IL2 replicated more efficiently in peripheral blood mononuclear cells in the absence of exogenously added IL-2. To determine whether this growth advantage would be of relevance in vivo, four juvenile rhesus monkeys were infected with SIV-IL2 and four monkeys were infected with a nef deletion mutant of SIV (SIVdeltaNU). After a peak in the cell-associated viral load 2 weeks postinfection, the viruses could barely be isolated 3 to 7 months postinfection. Mean capsid antigen levels were higher in the SIV-IL2 group than in the nef deletion group 2 weeks postinfection. Viruses reisolated from the SIV-IL2-infected animals expressed high levels of IL-2 during the acute phase of infection. Deletions in the IL-2 coding region of SIV-IL2 were observed in two of the SIV-IL2-infected macaques 3 months postinfection. Urinary neopterin levels, a marker for unspecific immune stimulation, were higher in the SIV-IL2-infected macaques than in SIVdeltaNU-infected animals during the acute phase of infection. The SIV-specific T-cell-proliferative response and antibody titers were similar in both groups. Cytotoxic T cells directed against viral antigens were detected in all SIV-IL2-infected macaques and in two of the SIVdeltaNU-infected animals. Expression of IL-2 did not seem to alter the attenuated phenotype of nef deletion mutants fundamentally, although there might have been a slight increase in virus replication and immune stimulation during the acute phase of infection. Deletion of the viral IL-2 gene 3 months postinfection could be a consequence of a selective disadvantage due to local coexpression of viral antigen and IL-2 in the presence of an antiviral immune response.     

The initiation of simian virus 40 DNA replication in vitro

DNA replication is a complicated process that is largely regulated during stages of initiation. The Siman Virus 40 in vitro replication system has served as an excellent model for studies of the initiation of DNA replication, and its regulation, in eukaryotes. Initiation of SV40 replication requires a single viral protein termed T-antigen, all other proteins are supplied by the host. The recent determination of the solution structure of the T-antigen domain that recognizes the SV40 origin has provided significant insights into the initiation process. For example, it has afforded a clearer understanding of origin recognition, T-antigen oligomerization, and DNA unwinding. Furthermore, the Simian virus 40 in vitro replication system has been used to study nascent DNA formation in the vicinity of the viral origin of replication. Among the conclusions drawn from these experiments is that nascent DNA synthesis does not initiate in the core origin in vitro and that Okazaki fragment formation is complex. These and related studies demonstrate that significant progress has been made in understanding the initiation of DNA synthesis at the molecular level.     

Pathogenic diversity of simian immunodeficiency viruses

The SIV family is a diverse group of viruses that vary considerably in pathogenesis and virulence in their natural host species or macaques. Although the disease induced by the SIVsm subtype in particular is remarkably similar to human AIDS, it must be remembered that this is an experimental animal model. Therefore, although the pathogenesis of SIVsm (and other viruses) in macaques offers an relevant animal model for pathogenesis and vaccine trials, the interactions of these viruses in their natural host, and virus-, or host-specific effects have been poorly characterized. This animal model offers a unique opportunity to study the details of the pathogenesis of immunodeficiency and to define host and viral factors responsible for disease progression.     

Genomic relationship of porcine hemagglutinating encephalomyelitis virus to bovine coronavirus and human coronavirus OC43 as studied by the use of bovine coronavirus S gene-specific probes

The genomic relationship of porcine hemagglutinating encephalomyelitis virus (HEV) to bovine coronavirus (BCV) and human coronavirus (HCV) strain OC43 was examined by dot blot hybridization assays. Two BCV S gene-specific probes were generated by polymerase chain reaction from the avirulent L9-strain of BCV. Probes were located in the S1 and the S2 region of the peplomeric (S) glycoprotein gene. The S1 probe (726 bp) hybridized with BCV and HCV-OC43, but not with HEV under moderate stringency hybridization conditions (50 degrees C). Only slight signals were present with mouse hepatitis virus (MHV) and no signals were observed with feline infectious peritonitis virus (FIPV) or canine coronavirus (CCV). At high stringency conditions (60 degrees C) the S1 probe hybridized with BCV only. Using the S2 probe (680 bp) under moderate stringency conditions, hybridization signals were obtained with BCV, HCV-OC43 and HEV (strains 67N, NT9, VW572). The signals obtained by the three HEV strains were altogether weaker than with BCV and HCV-OC43. The S2 probe did not react with MHV, FIPV and CCV. At high stringency the S2-specific probe hybridized with BCV and HCV-OC43 but did not hybridize with HEV. Nucleotide sequence analysis of the region covering the S2 probe in HEV revealed 92.6% nucleotide sequence homology to BCV and 91.9% to HCV-OC43. In contrast, the region covering the S1 probe in HEV could not be amplified using the BCV S1-specific primers. The hybridization and sequencing results thus indicate a closer genomic relationship between BCV and HCV-OC43 than there is between HEV and BCV or HCV-OC43 respectively.     

A malignant astrocytoma containing simian virus 40 DNA in a macaque infected with simian immunodeficiency virus

Polyomaviruses have proven oncogenicity in nonhost experimental animals; however, studies concerning the association between human brain tumors and simian and human polyomaviruses have yielded inconclusive results. We examined the relationship of SV40 to a malignant astrocytoma found in the right frontal lobe of a pigtail macaque (Macaca nemestrina) infected with simian immunodeficiency virus (SIV). Consistent with the histologic diagnosis, the tumor was immunoreactive with antibodies to S-100 protein, vimentin, and glial fibrillary acidic protein, but negative for neurofilament protein, synaptophysin, neuron-specific enolase, and chromogranin A. At the time of SIV inoculation, the animal was seropositive for SV40. Polymerase chain reaction assay of tumor DNA, but not normal brain DNA, yielded a 300 base-pair fragment corresponding to the carboxy-terminal coding region (C-terminus) of the large T antigen gene of SV40, suggesting an association with the tumor.     

Neutralization sensitivity of cell culture-passaged simian immunodeficiency virus

CEMx174- and C8166-45-based cell lines which contain a secreted alkaline phosphatase (SEAP) reporter gene under the control of a tat-responsive promoter derived from either SIVmac239 or HIV-1(NL4-3) were constructed. Basal levels of SEAP activity from these cell lines were low but were greatly stimulated upon transfection of tat expression plasmids. Infection of these cell lines with simian immunodeficiency virus (SIV) or human immunodeficiency virus type 1 (HIV-1) resulted in a dramatic increase in SEAP production within 48 to 72 h that directly correlated with the amount of infecting virus. When combined with chemiluminescent measurement of SEAP activity in the cell-free supernatant, these cells formed the basis of a rapid, sensitive, and quantitative assay for SIV and HIV infectivity and neutralization. Eight of eight primary isolates of HIV-1 that were tested induced readily measurable SEAP activity in this system. While serum neutralization of cloned SIVmac239 was difficult to detect with other assays, neutralization of SIVmac239 was readily detected at low titers with this new assay system. The neutralization sensitivities of two stocks of SIVmac251 with different cell culture passage histories were tested by using sera from SIV-infected monkeys. The primary stock of SIVmac251 had been passaged only twice through primary cultures of rhesus monkey peripheral blood mononuclear cells, while the laboratory-adapted stock had been extensively passaged through the MT4 immortalized T-cell line. The primary stock of SIVmac251 was much more resistant to neutralization by a battery of polyclonal sera from SIV-infected monkeys than was the laboratory-adapted virus. Thus, SIVmac appears to be similar to HIV-1 in that extensive laboratory passage through T-cell lines resulted in a virus that is much more sensitive to serum neutralization.     

Genetic control of anti-idiotypic vaccination against coronavirus infection

The idiotypic network can be experimentally altered to induce protective immune responses against microbial pathogens. Both internal image and noninternal image anti-idiotypic (anti-Id) antibodies have been shown to trigger antigen (Ag)-specific immune responses. Therefore, mechanisms of anti-Id vaccination appear to go beyond structural mimicry of Ag, but remain undefined. Using the neurotropic murine coronavirus animal model, we have previously shown that a polyclonal noninternal image anti-Id (Ab2) could vaccinate BALB/c mice. To characterize its mode of action, we have examined the immune modulating capability of this Ab2 in vivo in strains of mice with different H-2 haplotypes. Even though only internal image anti-Id are expected to induce non-genetically restricted immunity, this noninternal image Ab2 induced protective immunity in four of eight genetically different strains of mice susceptible to coronavirus infection. These were BALB/c (H-2d), DBA/2 (H-2d), DBA/1 (H-2q), and SWR (H-2q) mice. Protection was generally correlated with the induction of specific antiviral Ab (Ab3) that showed biological properties, such as virus neutralization in vitro, similar to the initial Ab1. To evaluate the genetic implication of the H-2 haplotypes in protection, congenic mice were also tested. Vaccination profiles suggest that cooperation between background gene(s) of the BALB/c mouse with H-2d and H-2q loci is necessary for an optimal protective immune response, although the main genetic element(s) regulating the antiviral response to Ab2 inoculation appeared to be located outside the major histocompatibility complex. These results are consistent with the ability of Ab2 to induce protective antiviral antibodies in genetically different animals by biological mimicry.     

Human coronavirus infections: importance and diagnosis

POORLY-KNOWN VIRUS: Coronaviruses, so named because of their sun-ray-like aspect, were discovered in the sixties. The biology of these RNA viruses is complex and poorly understood. KNOWN PATHOGENS: Coronaviruses are known pathogens in veterinary medicine, causing disease states in several domestic species. In human medicine, they can cause benign respiratory infections, but few laboratories include coronaviruses in their routine diagnostic tests. SUSPECTED PATHOGENS: There is some data in the literature suggesting coronaviruses might be implicated in more severe diseases including multiple sclerosis, necrotizing enterocolitis, and lower respiratory tract infections, particularly in infants. IMPROVING DIAGNOSTIC METHODS: Due to the lack of reliable and sensitive diagnostic techniques, it is impossible to date to correctly assess the medical impact of these ubiquitous and endemic viruses. Molecular biology techniques enabling detection of human coronavirus infections should be applied to verifying the suspected implication of these viruses in diverse disease states.     

Early physiological abnormalities after simian immunodeficiency virus infection

Central nervous system (CNS) damage and dysfunction are devastating consequences of HIV infection. Although the CNS is one of the initial targets for HIV infection, little is known about early viral-induced abnormalities that can affect CNS function. Here we report the detection of early physiological abnormalities in simian immunodeficiency virus-infected monkeys. The acute infection caused a disruption of the circadian rhythm manifested by rises in body temperature, observed in all five individuals between 1 and 2 weeks postinoculation (p.i.), accompanied by a reduction in daily motor activity to 50% of control levels. Animals remained hyperthermic at 1 and 2 months p.i. and returned to preinoculation temperatures at 3 months after viral inoculation. Although motor activity recovered to baseline values at 1 month p.i., activity levels then decreased to approximately 50% of preinoculation values over the next 2 months. Analysis of sensory-evoked responses 1 month p.i. revealed distinct infection-induced changes in auditory-evoked potential peak latencies that persisted at 3 months after viral inoculation. These early physiological abnormalities may precede the development of observable cognitive or motor deficiencies and can provide an assay to evaluate agents to prevent or alleviate neuronal dysfunction.     

Mechanisms of protection induced by attenuated simian immunodeficiency virus. IV. Protection against challenge with virus grown in autologous simian cells

Attenuated simian immunodeficiency virus (SIV) induces potent protection against infection with wild-type virus, but the mechanism of this immunity remains obscure. Allogeneic antibodies, which arise within animals as a result of SIV infection, might protect against challenge with exogenous SIV grown in allogeneic cells. To test this hypothesis, eight macaques were infected with attenuated SIV and subsequently challenged with wild-type SIV grown in autologous cells or heterologous cells. The results clearly demonstrated that animals infected with attenuated SIV are protected against wild-type SIV grown in autologous or heterologous cells. Thus, the hypothesis that live attenuated SIV protects by the induction of allogeneic antibodies is not tenable.     

Coinfection of macaques with simian immunodeficiency virus and simian T cell leukemia virus type I: effects on virus burdens and disease progression

To test the hypothesis that coinfection with human immunodeficiency virus (HIV) and human T cell leukemia/lymphoma virus types I or II (HTLV-I or -II) accelerates progression to AIDS, pig-tailed macaques were inoculated with the simian counterparts, SIV and STLV-I. During 2 years of follow-up of singly and dually infected macaques, no differences in SIV burdens, onset of disease, or survival were detected. However, in the first coinfected macaque that died of AIDS (1 year after infection), >50% of CD4+ and CD8+ lymphocytes expressed CD25. On the basis of the low incidence of HTLV-I- and STLV-I-associated disease during natural infections, this early evidence of neoplastic disease was unexpected. While these results demonstrate that coinfection with SIV and STLV-I has no influence on the development of immunodeficiency disease, they do establish a reliable macaque model of persistent STLV-I infection.     

Microglia-passaged simian immunodeficiency virus induces neurophysiological abnormalities in monkeys

Four rhesus macaques were inoculated intravenously with a cryopreserved stock of microglia obtained from a simian immunodeficiency virus (SIV)-infected rhesus macaque. Before infection, three of the four monkeys were trained and tested daily on a computerized neuropsychological test battery. After SIV infection, behavioral testing continued to monitor deficits associated with disease progression. Five additional age-matched, behaviorally trained monkeys served as controls. Neurophysiological testing for visual and auditory evoked responses was accomplished 37-52 weeks after infection in all monkeys. Subsequently, all four SIV-infected monkeys and one control subject were sacrificed, and samples of brain tissue were taken for pathological analysis. SIV-infected monkeys demonstrated abnormal responses in both auditory and visual evoked responses. In addition, around the time of electrophysiological recording, all three SIV-infected, behaviorally trained monkeys exhibited significant decreases in progressive-ratio performance, reflecting a reduction in reinforcer efficacy. One subject also demonstrated impairments in shifting of attentional set and motor ability at that time. Neuropathological evaluation revealed that all four SIV-infected monkeys exhibited numerous perivascular and parenchymal infiltrating T cells. These findings document that SIV causes electrophysiological, behavioral, and neuropathological sequelae similar to what has been observed in the human neuroAIDS syndrome. Our observations further validate the simian model for the investigation of the pathogenesis of AIDS dementia and for the investigation of drugs with potential therapeutic benefits.     

The role of upstream U3 sequences in the pathogenesis of simian immunodeficiency virus-induced AIDS in rhesus monkeys

The nef reading frame overlaps about 70% of the U3 region of the 3' long terminal repeat (LTR) in primate lentiviruses. We investigated the functional role of these overlapping U3 sequences by analyzing the properties of three mutant forms of the pathogenic SIVmac239 clone. In mutant UScon, 90 of 275 bp in the upstream sequences (US) of U3 were changed in a conservative fashion without changing the predicted nef coding sequence. In mutant USnon, 101 of 275 bp in this region were changed in a nonconservative fashion, again without changing the predicted nef coding sequence. In mutant delta US, 275 bp in this region were deleted. Full-size, immunoreactive nef protein was synthesized in cells infected with the UScon and USnon mutants. The USnon and delta US mutants replicated with similar kinetics and to similar extents as wild-type, parental SIVmac239 in primary rhesus monkey peripheral blood mononuclear cell (PBMC) cultures. The UScon mutant replicated with slightly delayed kinetics in rhesus monkey PBMC cultures. In the CEMx174 cell line, the delta US mutant replicated similarly to the wild type, but the UScon and USnon mutants replicated with significantly delayed kinetics. Analysis of LTR-driven chloramphenicol acetyltransferase (CAT) activity and the effects of 5-azacytidine on virus replication suggested that the growth defect of the point mutants in CEMx174 cells was due in whole or in part to the introduction of multiple CG methylation sites in proviral DNA. Rhesus monkeys were experimentally infected with the UScon and USnon mutants, and the characteristics of the infection were compared with those of the parental SIVmac239. Analysis of the levels of plasma antigenemia, virus load, and CD4+ cells in PBMC revealed no decreased virulence of the mutant viruses. Analysis of lymph node biopsies taken from animals that received mutant viruses revealed histologic changes and levels of virus expression indistinguishable from those of the wild type. Furthermore, the wild-type behavior of the mutant viruses in rhesus monkeys occurred without any specific reversional events through at least 20 weeks of infection. These results, and the recent results of Kirchhoff et al. (F. Kirchoff, H. W. Kestler III, and R. C. Desrosiers, J. Virol. 68:2031-2037, 1994), suggest that these upstream sequences in U3 are primarily or exclusively nef coding sequence.     

Infectious simian varicella virus expressing the green fluorescent protein

PURPOSE: To determine if vascular occlusion and nonperfusion is associated with the outer retinal atrophy, retinopathy, and choroidopathy (chorioretinopathy) that occurs in the alpha H beta S[beta MDD] and alpha H beta S [alpha MD beta MDD] transgenic mouse models of sickle cell disease. METHODS: Mice from the alpha H beta S[beta MDD] and alpha H beta S[alpha MD beta MDD] transgenic mouse lines that express high levels of human beta S globin were anesthetized and administered horseradish peroxidase (HRP) intracardially. After 1 min, the animals were sacrificed, and the retina from one eye was excised, fixed, and developed in diaminobenzidine (DAB). The contralateral eye was fixed, embedded whole in glycol methacrylate, and HRP developed in 2.5 microns sections. RESULTS: HRP reaction product (HRP-RP) and stained erythrocytes (RBCs) (due to endogenous peroxidase) were diffusely distributed within all vascular lumens in flatmount retinas from control animals (littermates homozygous for the mouse Beta Major deletion not expressing the beta S transgene). In 42.5% of the transgenic mice expressing beta S without any proliferative retinopathy, many blood vessels contained RBC plugs and lacked lumenal HRP-RP. In addition to packed RBCs, fibrin was sometimes present at sites of occlusion. In sections from whole eyes of the same animals, foci of photoreceptor degeneration were associated with areas of choriocapillaris nonperfusion (lumen that lacked HRP-PR). In areas with normal photoreceptors, the choriocapillaris appeared perfused (HRP-RP was present). In animals with proliferative chorioretinopathy, some neovascular formations lacked luminal HRP-RP, suggesting autoinfarction. CONCLUSIONS: Nonperfused retinal and choroidal vessels were observed in mice from the alpha H beta S[beta MDD] and alpha H beta S[alpha MD beta MDD] lines without retinal and choroidal neovascularization, whereas, all mice with neovascularization had nonperfused areas. Furthermore, small foci of PR loss were associated with areas of nonperfused choriocapillaris. These results suggest that sickle cell-mediated vaso-occlusions are an initial event in the chorioretinopathy and outer retinal atrophy that occurs in these models.     

The acoustic properties of snores

This study was undertaken in an attempt to characterize the acoustic properties of snoring sounds in the time and frequency domains, and to correlate between these properties and the mechanical events underlying their production. Three experimental set-ups were used: 1) Dog model--six mongrel dogs, in which partial upper airway obstruction was created by an implanted supraglottic balloon. Flow, supraglottic pressure, and snoring sounds were recorded during different degrees of obstruction. Fifteen to 20 snores from each dog (total 100 snores) were analysed. 2) Simulated human snores--Six simulated snores from each of four subjects were recorded in two locations (trachea and ambient) with simultaneous airflow, and their correlations examined. 3) Snoring patients--snores were recorded with an ambient microphone from nine subjects with "heavy" snoring and no obstructive sleep apnoea (OSA). Forty to 50 snores from each subject were analysed (total of 400 snores). The snoring sound was analysed in the time (time-expanded waveform) and frequency (power spectrum) domains. After analysing these snores, we were able to identify two dominant patterns which are distinctly different from each other: the "simple-waveform" and the "complex-waveform". The complex-waveform snore is characterized by repetitive, equally-spaced, train of sound structures, starting with a large deflection followed by a decaying amplitude wave. In the frequency domain, it is characterized by multiple, equally-spaced peaks of power (comb-like spectrum). Simple-waveform snores have a quasi-sinusoidal waveform, with a range of variants, and almost no secondary internal oscillations. Their power spectrum contains only 1-3 peaks, of which the first is the most prominent. We developed a mathematical representation of these waveforms, which is presented along with its implications. The complex-waveform snores result from colliding of the airway walls and represent actual brief airway closure. Simple-waveform snores are of higher frequency and probably result from oscillation around a neutral position without actual closure of the lumen.     

The J domain of simian virus 40 large T antigen is required to functionally inactivate RB family proteins

Transformation by simian virus 40 large T antigen (TAg) is dependent on the inactivation of cellular tumor suppressors. Transformation minimally requires the following three domains: (i) a C-terminal domain that mediates binding to p53; (ii) the LXCXE domain (residues 103 to 107), necessary for binding to the retinoblastoma tumor suppressor protein, pRB, and the related p107 and p130; and (iii) an N-terminal domain that is homologous to the J domain of DnaJ molecular chaperone proteins. We have previously demonstrated that the N-terminal J domain of TAg affects the RB-related proteins by perturbing the phosphorylation status of p107 and p130 and promoting the degradation of p130 and that this domain is required for transformation of cells that express either p107 or p130. In this work, we demonstrate that the J domain of TAg is required to inactivate the ability of each member of the pRB family to induce a G1 arrest in Saos-2 cells. Furthermore, the J domain is required to override the repression of E2F activity mediated by p130 and pRB and to disrupt p130-E2F DNA binding complexes. These results imply that while the LXCXE domain serves as a binding site for the RB-related proteins, the J domain plays an important role in inactivating their function.     

The integration of object properties

Growth plate cartilage cell express receptors for, and are affected by both IGF-I and 1 alpha, 25(OH)2D3. The studies were undertaken to investigate interaction between these two hormone systems, that is, (i) to study effects of 1 alpha, 25(OH)2D3 on IGF-type 1 receptors (IGFIR), on IGF-I stimulated cell replication, colony formation, and on alkaline phosphatase activity (AP), and conversely, (ii) to study the effect of IGF-I on vitamin D receptor (VDR) expression on 1 alpha, 25(OH)2D3 stimulated growth parameters and on AP activity. Freshly isolated rat tibial chondrocytes were grown in monolayer cultures, (serum-free) or in agarose stabilized suspension cultures (0.1% FCS). Vitamin D receptor and IGFIR were visualized by immunostaining with the monoclonal antibody (mAb) 9A7 gamma and mAb alpha IR3, respectively, and quantitated by RT-PCR for mRNA and by Scatchard analysis using [3H]-1,25(OH)2D3 and [125I]-alpha IR3. Cell proliferation was measured by [3H]-thymidine incorporation, growth curves in monolayer cultures, and by colony formation in agarose-stabilized suspension cultures. IGF-I dose-dependently increased [3H]-thymidine incorporation. 1 alpha, 25(OH)2D3, but not 1 beta, 25(OH)2D3 was stimulatory at low ((10-12 M) and slightly inhibitory at high (10-8 M) concentrations. The effect of IGF-I was additive to that of 1 alpha, 25 (OH)2D3 [IGF-I 60 ng/ml, 181 +/- 12.7; 1 alpha, 25(OH)2D3 10(-12) M, 181 +/- 9.8%, IGF-I + 1 alpha, 25(OH)2D3, 247 +/- 16.7%, P < 0.05 by ANOVA] and specifically obliterated by polyclonal IGF-I antibody (AB-1). Interaction could also be confirmed in suspension cultures. IGFIR mRNA and [125I]-alphaIR3 binding was increased by low (10(-12) m) but not by high (10(-8) M) concentrations of 1 alpha, 25(OH)2D3. Homologous up-regulation by IGF-I (60 ng/ml) was specifically inhibited by AB-1 and markedly amplified by coincubation with 1 alpha, 25(OH)2D3 (10(-12)m). Immunostaining with alpha IR3 showed specific IGFIR expression in rat growth cartilage, but not liver tissue. Stimulation of chondrocytes with 1 alpha, 25(OH)2D3 or IGF-I suggested some increase of receptor expression in single cells, but the predominant effect was increased recruitment of receptor positive cells, Vitamin D receptor expression was markedly stimulated (fourfold) by IGF-I (60 ng/ml), but not IGF-II and inhibited by actinomycin D. This study shows that IGF-I and 1 alpha, 25(OH)2D3 mutually up-regulate their respective receptors in growth plate chondrocytes. In parallel, they have additive effects on cell proliferation and colony formation suggesting independent effector pathways.     

The antioxidant properties of lycopene

The antioxidant properties of the carotenoid lycopene were compared in three different model oxidative systems. In egg yolk liposomes, in the presence of 2.5 mM FeSO4 and 200 mM ascorbate, lycopene, alpha-tocopherol, and beta-carotene inhibited the accumulation of lipid peroxidation products reacting with 2-thiobarbituric acid (TBARS) in a dose-dependent mode, with the concentration of half-inhibition being 80, 30 and 130 mM, respectively. In the liposomes subjected to illumination with a He-Ne laser (632.8 nm) at a dose of 10.5 J/cm2, in the presence of 32.5 micrograms/ml hematoporphyrin derivatives (Fotogem, NIOPIC, Russia) TBARS accumulated, and this effect was inhibited by lycopene, alpha-tocopherol, and dihydroquercetin with approximately equal efficiencies (the half-inhibition concentrations were 10(-5) mM). In both systems studied, sodium azide at a concentration of 10 mM inhibited the TBARS accumulation by no more than 20%. Apparently, the inhibitory action of not only alpha-tocopherol, but also beta-carotene and lycopene was the result of their antiradical action, rather than quenching of the singlet oxygen in an aqueous medium. The introduction of lycopene, as well as beta-carotene in liposomes subjected to Fe(2+)-induced lipid peroxidation decreased the chemiluminescence (CL) intensity at the stage of CL slow flash, with no essential influence on the lag period. These data suggest that the effect of lycopene on lipid peroxidation was the result of its interaction with free radicals rather than chelating ferrous ions. The antiradical activity of lycopene was also confirmed by the method of luminol photochemiluminescence (PCL). Lycopene increased the PCL lag period (L) and decreased the PCL amplitude (A), which implies its antiradical and SOD-like activity in this system.