R. Dörries

Viral particles induce Ia antigen expression on astrocytes

Recent studies have shown that gamma-interferon (IFN-gamma) induces the expression of Ia antigen on astrocytes. This observation is of immunological significance because such activated astrocytes can act as antigen-presenting cells, as demonstrated with myelin basic protein for antigen-specific encephalitogenic T-cell lines. However, the lack of lymphatic drainage in brain and the presence of the so-called blood-brain barrier restricting traffic of cells and macromolecules suggests that IFN-gamma may not be readily available, at least during the initial phases of viral infections. The question therefore arises as to whether astrocytes can be induced to express Ia antigens by other signals directly related to viral infection and possibly independent of IFN-gamma. In the present report we demonstrate that a neurotropic murine hepatitis virus induces expression of Ia antigen on astrocytes in tissue culture without infection, rendering these brain cells competent to participate directly in the immune response to a viral infection.

Detection and identification of virus-specific, oligoclonal IgG in unconcentrated cerebrospinal fluid by immunoblot technique*

A technique is described which allows the detection of virus-specific oligoclonal IgG in unconcentrated cerebrospinal fluid (CSF) from patients with virus infections of the central nervous system. CSF is isoelectrically focused in agarose gels and immunoglobulins are blotted to nitrocellulose filters, passively loaded with either anti-human IgG or viral antigen. Transferred total IgG, as well as virus-specific IgG, is identified by the use of peroxidase-labelled anti-human IgG and 4-chloro-1-naphthol as a precipitating peroxidase substrate. Application of this assay in cases of SSPE, mumps meningitis and herpes simplex encephalitis demonstrates sensitivity and possible suitability of this technique for use in diagnosis of virus infections of the CNS.

LYMPHOCYTE SUBSETS AND EXPRESSION OF DIFFERENTIATION MARKERS IN BLOOD AND LYMPHOID ORGANS OF RHESUS MONKEYS

Rhesus macaques are invaluable experimental animals in biomedical research. Using three color flow cytometry, we screened anti-human antibodies for crossreactivity with macaque cells in order to determine the distribution of functionally important lymphocyte subsets in blood, lymph nodes (LN), and spleen. NK-cells are almost completely absent in LN. The percentage of B-cells expressing CD80, CD86, and the level of expression of CD20 is higher in blood than in LN. In contrast, a higher proportion of B-cells in LN stains positive for CD21 and CD35. Whereas the number of CD29hi expressing T-cells is lower, CD69 is expressed on more T-cells in LN than in blood. About one-third of CD8+ T-cells in blood are CD28-, a subset with a unique pattern of antigen expression which cannot be found in LN. In contrast to humans, a relatively high proportion of T-cells in blood also express the co-stimulatory molecules CD80 and CD86. With increasing age, the proportion of B-cells in blood declines, whereas the percentage of T-cells rises. In addition, the proportion of CD29hi expressing T-cells increases among both the CD4+ and CD8+ subsets.

Specificity of IgM Antibodies in Acute Human Coxsackievirus B Infections, Analysed by Indirect Solid Phase Enzyme Immunoassay and Immunoblot Technique

The specificity of the IgM response in acute human coxsackievirus B infections was examined by indirect solid phase enzyme immunoassay and immunoblot techniques. IgM antibodies detected by ELISA were either strictly type-specific, type-predominant or group-reactive to coxsackieviruses B-1 to B-5. Homotypic and type-dominant responses were clearly correlated with the serotype isolated from the patient. Analysis of ELISA antigens by SDS-gel electrophoresis, protein transfer and subsequent immunodetection of individual virus polypeptides, revealed VP1 as the major antigen; it was detected by homotypic as well as heterotypic serum specimens.

The immune system response to viral infection of the CNS

Abstract In immunological terms the CNS is at a severe disadvantage in its ability to respond to infection by virus. First, both glial and neuronal cells normally do not express molecules of the major histocompatibility complex. Second, the most efficient cells for stimulating an immune response (leucocyte dendritic cells) are not present in the healthy CNS; and third, there is no specialized lymphatic drainage from the CNS to lymph nodes to enable the immune system to be quickly informed of the presence of an infection. Nevertheless, the immune system apparently copes with the vast majority of viral infections in the CNS. This is clearly evidenced by the reactivation of latent CNS viral infections in some immunosuppressed patients and the dramatic increase in the seventy of CNS disease in young or otherwise immunologically incompetent experimental animals infected with neurotropic viruses. The routes by which the CNS and the immune system may communicate and the varied ways in which an immune response may affect the outcome of a viral infection of the CNS are discussed.

Analysis of oligoclonal antibody bands against individual HIV structural proteins in the CSF of patients infected with HIV

SummaryIntrathecal antibody responses to HIV were investigated by a highly sensitive immunoblot assay. Serum and CSF specimens were tested for reactivity with the recombinant HIV gag proteins p15, p17 and p24 and with the recombinant transmembrane protein p41. Autochthonous production of virus-specific IgG to one or more HIV structural proteins was seen in 8 of 10 asymptomatic seropositive subjects, in 3 of 4 men with AIDS-related complex, and in 9 of 13 patients with AIDS. These results were consonant with an elevated CSF/serum antibody ratio to total HIV antigen. The high frequency of local HIV-specific antibody synthesis in seropositive individuals without related clinical symptoms indicates an early involvement of the CNS in HIV infections.

Detection of enterovirus specific IgG and IgM antibodies in humans by an indirect solid phase radioimmunoassay.

The development of a solid phase radioimmunoassay which is able to detect virus-specific IgG and IgM antibodies in serum specimens from patients with enterovirus infections is described. Viral antigen partially purified from infected tissue culture fluid was adsorbed passively to individual polystyrene microtiter wells. Dilutions of sera were incubated on these antigens and bound anti-viral antibodies were monitored by the addition of 125-iodine labeled anti-human-IgG or anti-human-IgM antibody. Specificity of the assay to detect virus-specific IgM antibody was ensured by highly specific anti-IgM antibody which did not cross react with IgG and 2-mercaptoethanol sensitivity of IgM antibody titers. Changes of IgM antibody titers clearly indicated a current infection by that virus strain which was isolated as etiological agent. Advantages and restrictions of the introduced radioimmunoassay are discussed.

Analysis of the intrathecal humoral immune response in Brown Norway (BN) rats, infected with the murine coronavirus JHM

Abstract Serum and CSF specimens from clinically healthy Brown Norway (BN) rats inoculated intracerebrally with corona virus JHM were analysed with respect to the state of the blood-brain barrier (BBB) and the intrathecal synthesis and isoelectric distribution of immunoglobulins (Ig). Increased CSF/serum ratios for Ig in the context of an intact BBB were never seen in the absence of intrathecal synthesis of virus-specific antibodies. Affinity-mediated immunoblot analysis revealed a broad pattern of virus-specific antibodies with embedded clusters of restricted heterogeneity, but no signs of oligoclonal Ig production carrying non-viral specificity. From these data it was concluded that BN rats do control the intracerebral spread of JHM virus effectively by a strong local virus-specific antibody response, thereby preventing a clinically apparent disease.

Murine coronavirus-induced encephalomyelitides in rats: Analysis of immunoglobulins and virus-specific antibodies in serum and cerebrospinal fluid

Abstract The humoral intrathecal immune response in coronavirus-induced demyelinating encephalomyelitis in rats associated with an autoimmune reaction to brain antigen, was analysed. The CSF of these animals revealed immune reactions which were directed against coronavirus and other, unknown, antigens. In general, no direct correlation between the disease, the state of the blood-brain barrier (BBB), intrathecal synthesis of Ig and the presence of virus-specific antibodies was detectable, suggesting that the humoral, in contrast to the cellular, immune response does not play a significant pathogenetic role in this CNS disease.

Evaluation of seroepidemiological associations between HIV-infection, hepatitis B and other sexually transmitted diseases in African patients

To assess the possible role of sexually transmitted diseases as cofactors for the spread of AIDS, 248 adult patients were tested for the presence of antibodies against human immunodeficiency virus (HIV), hepatitis B virus (HBV) and syphilis. The survey was conducted in a hospital at Kagondo, Kagera Region, Northwest Tanzania, Africa. Subjects were randomly chosen from the outpatient clinic to include those with and without sexually transmitted diseases, as well as AIDS/pre-AIDS patients. The data were univariately and multivariately analysed by linear logit models, including interactions of demographic parameters. The results obtained reveal a strong association between the presence of antibodies against HIV, syphilis and HBV, respectively. The HBV/HIV-correlation remained stable in the multivariate analysis including interactions of social parameters, in contrast to the syphilis/HIV-correlation. We assume that this reflects the lower virulence of HBV as compared to that of syphilis. The prevalence of anti-HBV antibodies seems to be a more reliable marker for high sexual activity than those against syphilis. The possibility that HBV and HIV act as cofactors for each others transmission could not be ruled out.