Persistent productive HIV infection in EBV-transformed B lymphocytes

The susceptibility to HIV infection of 14 B-cell lines established from five healthy HIV seronegative and from six HIV seropositive subjects by lymphocyte transformation with EBV and/or by lymphocyte cultivation with cyclosporin A was studied. Although the cell lines contained different proportions of CD4-positive cells, as shown by flow cytometry, all of them could be infected with the SF-2 strain of HIV. Infection was blocked by a monoclonal antibody directed against the viral attachment site of the CD4 molecule, even in a line that lacked demonstrable CD4 receptors. B-cell lines with high proportions of CD4-expressing cells produced HIV p24 antigen more rapidly and at higher concentrations than cell lines with low CD4 expression. Although HIV infection resulted in some cytopathic effects, it was possible to cultivate the infected cells for more than 8 months without refeeding the cultures with uninfected cells. Even in long-term cultures, there was a continuous production of infectious HIV, as detected by transfer of culture supernatants to other susceptible cell lines. The production of viral antigens was consistently more pronounced in the B-cell line with the highest CD4 positivity than it was in a permissive T-cell line (HUT-78) infected in the same manner. These results indicate that HIV can chronically and productively infect transformed B cells via interaction with CD4 molecules. Thus it is possible that B cells may constitute a source of infectious virus in HIV-infected EBV-positive individuals.     

Visualization of defective measles virus particles in cerebrospinal fluid in subacute sclerosing panencephalitis

Measles virus particles were visualized in the CSF of two patients with verified subacute sclerosing panencephalitis (SSPE) by using scanning electron microscopy. Immunologic identification of the accumulated particles was performed with monoclonal antibodies, directly conjugated to carboxylated microspheres, specific for different measles virus antigens. The beads were amassed on the filter surface after a 1-hr incubation in the CSF. Spherical particles with a diameter ranging between 150 and 500 nm were detected. Such particles bound specifically to latex beads covered by monoclonal antibodies to measles virus hemagglutinin but not to beads conjugated with monoclonal antibodies specific for nucleoprotein. Adding the two monoclonal antibodies to measles virus hemagglutinin to the CSF agglutinated the virus particles in a dose-dependent way. Further, no particles in the CSF bound to microspheres conjugated with monoclonal antibodies to non-related antigens of Sendai virus, cytomegalovirus, or human immunodeficiency virus. Similarly sized particles were also identified by transmission electron microscopy after concentrating the CSF.     

Combined treatment of symptomatic human immunodeficiency virus type 1 infection with native interferon-alpha and zidovudine.

Patients with advanced human immunodeficiency virus type 1 (HIV-1) infection who had p24 antigen despite treatment with zidovudine (AZT) for 4-28 months received 3 x 10(6) IU of native interferon-alpha (IFN-alpha) daily for 3 months. Infectious HIV was detected in the plasma of all patients, in most cases at high titers, before IFN-alpha treatment. There was no correlation between HIV titers and p24 antigen levels. Antiviral activity, as measured by significantly decreased levels of infectious virus or p24 antigen, was observed in six of eight completely treated but in only one of nine incompletely treated patients. After termination of IFN-alpha treatment, there was a significant rise of p24 antigen levels. During IFN treatment, absolute CD4 cell counts showed a tendency toward an increased rate of decline. The side effects were unexpectedly severe. Despite its anti-HIV effect in vivo, IFN-alpha in the dosages used does not seem to be a viable additional treatment for severely immunodeficient patients in ongoing AZT therapy.     

Growth phase related loss of measles virus surface-associated antigens and cytotoxic susceptibility in persistently infected cells.

Fluctuations in the expression of measles virus surface-associated antigens in persistently infected human Lu 106 cells were analysed by the use of human sera which preferentially reacted with the haemolysin or haemagglutinin component. The variations observed correlated with the proportion of cells expressing surface-antigen, as examined in population analysis by indirect immunofluorescence, a radio-labelled antiglobulin technique and a cytotoxicity assay. Microfluorometric analysis revealed no changes in antigen expression at the single-cell level. The number of cells that were positive by immunofluorescence among exponentially growing, low density cells remained relatively constant. These cells were more susceptible to cytotoxicity mediated by both antisera and complement than cells seeded at high density and kept in the stationary phase. The percentage of fluorescent cells among the latter cells gradually decreased. Thus cytotoxic susceptibility was related to the proportion of the total cell population that was antigen-bearing, rather than to variations in the expression of antigen at the single-cell level. In mitotic cells, polarization of antigen, as measured by indirect immunofluorescence of pre-fixed cells, was frequently seen. Often only one of the daughter cells expressed surface antigen. The results imply that cells in stationary phase may lose antigen from their surface, possibly by shedding, and furthermore that re-expression would demand a new cell cycle.     

Long-term pattern of HIV-1 RNA load in perinatally infected children.

The objective of this study was to describe the natural history of HIV-1 RNA load in vertically HIV-1-infected children. HIV-1 RNA in 156 plasma or serum samples (1-14, median 4 from each child) from 32 vertically HIV-1-infected children was detected with the NASBA technique (Organon Teknika, The Netherlands). Twenty-one children were prospectively followed from birth, and 11 were identified and included at the age of 7-89 (median 61) months. The highest numbers of HIV-1 RNA copies were seen at 1.5-3 months of age. A quadratic curve model showed a reduction of HIV-1 RNA with increasing age up to approximately 8 years, and thereafter increasing numbers, p(age) = 0.002, p(age2) = 0.008. This pattern was not typical for individual children in whom a great variation in HIV-1 RNA numbers was seen over time. The interval from birth to the first HIV-1 RNA peak ranged from 1.5 months to more than 2 years. The HIV-1 RNA levels remained relatively high and fluctuating over the years in symptomatic as well as in long-term asymptomatic children. This makes HIV-1 RNA determination in children more difficult to use than in adults, as the only tool for prediction of disease progression and for initiation of therapy.