New tools in HCV diagnosis, in light of the enhanced awareness and the new drugs for treatment: SMARTube and stimmunology.

With improved HCV therapy, challenges regarding HCV diagnosis, such as seronegative window period, false positive readings, and differentiation between recent, chronic, and resolved infections, are of increasing importance. To address these challenges an innovative device--SMARTube HIV & HCV--was used. Blood samples were tested for anti-HCV antibodies before and after incubation in the SMARTube, which promotes the in vitro stimulation of in vivo HCV primed lymphocytes, thus enhancing levels of anti-HCV antibodies.

The challenges of hepatitis C diagnosis and the potential role of Stimmunology™ to address them.

The diagnosis of HCV infection is hindered by the long seronegative window period, the high rate of false-positives and the need to differentiate between current and cleared infection. Stimmunology™ is a technology by which antibody production can be stimulated, even in a whole blood sample, in vitro. Such stimulation leads to an increase in HCV antibody levels in the blood sample, enabling the detection of HCV infection prior to seroconversion.

Detecting seronegative-early HIV infections among adult versus student Kenyan blood donors, by using Stimmunology.

Background: Undetectable HIV infection in blood banks poses a serious threat to public health. Thus, donations from high school students are preferred over adult samples in Kenyan blood banks, due to lower HIV infection prevalence within this population, as detected by conventional serology testing. However, the number of recently infected individuals remains difficult to identify, as HIV-induced immunological window periods can span months.

HIV type 1 infection among Ethiopian immigrants to Israel: enhanced in vitro antibody stimulation for estimating the length of the window period.

The window period between infection and seroconversion varies based on viral genetics, dose and route of transmission, host genetics, and environmental factors. The in vitro Stimmunology blood pretreatment assay was utilized to promote the synthesis of HIV-specific antibodies in efforts to define the window period between infection and seroconversion. Ethiopians seeking immigration to Israel while in refugee camps provided a unique cohort to perform a comparative analysis of the window period between HIV-1 infection and diagnosis utilizing conventional Ab-ELISA and our laboratory established an in vitro Stimmunolog assay.

Pending problem of "silent" human immunodeficiency virus infection.

The problem of "silent" HIV infection is reviewed. Overall, the number of proven "silent" infection in several at-risk populations, including HIV exposed health-care workers, homosexuals, IV drug addicts and children born to HIV-infected mothers, has been very low. Contrary to these observations, we describe a very high prevalence of HIV specific immunity and positive HIV specific PCR signals in an Ethiopian immigrant population recently arrived in Israel.

Evidence for simian immunodeficiency virus-specific IgM and IgG response in peripheral blood mononuclear cells of serum enzyme-linked immunosorbent assay-negative nonhuman primates.

In vitro polyclonal activation of peripheral blood mononuclear cells (PBMCs) from 70% of the simian immunodeficiency virus (SIV) serum enzyme-linked, immunosorbent assay (ELISA)-negative sooty mangabeys leads to synthesis and release of low but significant and reproducible levels of SIV-reactive antibodies, as determined by ELISA and Western blot analysis. The predominant isotype of SIV-reactive antibodies in the pokeweed mitogen (PWM) supernatant fluids from serum ELISA-negative mangabeys is IgM, whereas the predominant isotype of SIV-reactive antibodies in seropositive mangabeys is IgG. Depletion of CD8+ cells led to a marked increase in the levels of SIV-reactive antibodies detected in supernatant fluids from PWM-induced cultures from the serum ELISA-negative mangabeys.

A new look at HIV transmission from seropositive mothers to their infants: the facts beyond serology.

Once the curtain of maternal antibodies is removed (12-18 months) only a fraction of the infants are seropositive. Some babies from whom virus has been isolated or detected in their cells subsequently become seronegative. What does the negative serology of these children really tell us about exposure to HIV? It is suggested that seroconverting is only one of the ways to respond to an HIV exposure from an infected mother; it is not the only or the best way.

Early and complete detection of HIV exposure.

Currently, HIV diagnosis relies on serology. Yet in groups at high risk for HIV serology is not sufficient because of the window period between infection and seroconversion. There is a growing body of reports on HIV-infected yet seronegative individuals.

Inhibition of cellular activation of retroviral replication by CD8+ T cells derived from non-human primates.

To test the hypothesis that CD8+ T cells inhibit viral replication at the level of cellular activation, an Epstein-Barr virus (EBV)-transformed cell line (FEc1) from a simian immunodeficiency virus (SIV)-seropositive sooty mangabey monkey was transfected with a human CD4 gene and shown to be replication-competent for HIV-1, HIV-2 and SIV. Utilizing a dual-chamber culture system, it was found that inhibition of viral replication can be mediated by a soluble factor. The FEc1 cell line was transiently transfected with an LTR-driven CAT reporter gene.

'Silent' HIV infection among wives of seropositive HIV carriers in the Ethiopian community in Israel.

We have previously described the phenomenon of 'silent HIV carriers', i.e. individuals with HIV specific immunity and a positive PCR for HIV-1, yet HIV seronegative.

Transmission of retroviral infection by transfusion of seronegative blood in nonhuman primates.

Techniques such as polyclonal B cell activation with pokeweed mitogen (PWM) and polymerase chain reaction (PCR) analysis have documented the existence of simian immunodeficiency virus (SIV)-and human immunodeficiency virus type 1-seronegative but infected humans and nonhuman primates. To establish whether blood from such seronegative but PWM- and PCR-positive monkeys can transmit infection, naive macaques were transfused with whole blood (n = 2) or cultured cells and supernatant fluid (n = 2) from two seronegative but PWM- and PCR-positive sooty mangabeys. After transfusion, three of the four recipients seroconverted, and peripheral blood mononuclear cells from all four recipients secreted SIV-reactive antibodies upon polyclonal activation in vitro and were SIV-positive by PCR that used highly specific gag primer pairs and probe.

Maternal transmission of SIVsmm in rhesus macaques.

Fifteen SIV-infected rhesus monkeys delivered 13 livebirths and two stillbirths; one livebirth died at three days of age. While all infants were culture-negative for SIV at birth, nine had maternal antibodies that disappeared by six months of age. Three infants subsequently seroconverted and became virus positive at 9-15 months.

Detection of occult simian immunodeficiency virus SIVsmm infection in asymptomatic seronegative nonhuman primates and evidence for variation in SIV gag sequence between in vivo- and in vitro-propagated virus.

Polymerase chain reaction techniques were used to identify simian immunodeficiency virus (SIV) SIVsmm gag sequences in genomic DNA isolated from peripheral blood mononuclear cells from naturally infected asymptomatic seropositive and seronegative sooty mangabeys (Cercocebus atys) and from experimentally infected but asymptomatic rhesus macaques (Macaca mulatta). The results indicate that most if not all SIV-seronegative mangabeys from the colony at the Yerkes Primate Center are in fact infected with SIVsmm despite their lack of humoral immune response, confirming previous immunological and virological observations made by our laboratory. Sequence analysis of these particular gag fragments from the mangabey revealed an average of 88% nucleotide sequence homology but 97% amino acid identity with the previously published sequence of the SIVsmmH4 clone.

Polyclonal B-cell activation reveals antibodies against human immunodeficiency virus type 1 (HIV-1) in HIV-1-seronegative individuals.

Identification of human immunodeficiency virus type 1 (HIV-1)-infected individuals is of paramount importance for the control of the spread of AIDS worldwide. Currently, the vast majority of screening centers throughout the world rely on serological techniques. As such, clinically asymptomatic but HIV-infected, seronegative individuals are rarely identified.

Does stem cell self renewal and progenitor cell commitment operate through an effector-memory cell mechanism?

We propose a model for stem cell self renewal and transition into commitment towards a variety of cell lineages. In this model the production of both "effector cells" (as represented by the mature cells in the different cell lineages) and of progenitor "memory" lymphocytes, takes place concomitantly. The experimental evidence supporting this model is as follows: Pure lymphocytic suspensions (PLS) are established and persist in culture when nude mouse-spleen and lymph-node cells are maintained on X-irradiated fibroblast monolayers in the presence of the S-phase cytotoxic agent cytosine arabinoside (Ara-C).