Background: Nicotine is the main culprit for dependence on tobacco-containing products, which in turn are a major etiologic factor for cardiovascular diseases and cancer. This publication describes a vaccine, which elicits antibodies against nicotine. The antibodies in the blood stream intercept the nicotine molecule on its way to its receptors and greatly diminish the nicotine influx to the brain shortly after smoking. Methods: The nicotine molecule is chemically linked to cholera toxin B as a carrier protein in order to induce antibodies. The potential to elicit antibodies after subcutaneous as well as intranasal immunization is evaluated. In order to simulate realistic conditions, nicotine pumps delivering the nicotine equivalent of 5 packages of cigarettes for 4 weeks are implanted into the mice 1 week prior to vaccination. The protective effect of the vaccine is measured 5 weeks after vaccination by comparing the influx of radiolabeled nicotine in the brains of vaccinated and non-vaccinated animals 5 min after challenge with the nicotine equivalent of 2 cigarettes. Results: The polyclonal antibodies induced by the vaccine show a mean avidity of 1.8 × 10⁷ l/Mol. Subcutaneous immunization elicits high antibody levels of the IgG class, and significant IgA antibody levels in the saliva of vaccinated mice can be found after intranasal vaccination. The protective effect also in the animals with implanted nicotine pumps is significant: less than 10% of radiolabeled nicotine found in the brains of non-vaccinated animals can be found in the brains of vaccinated animals. Conclusions: These data provide credible evidence that a vaccine can break the vicious circle between smoking and instant gratification by intercepting the nicotine molecule. Astonishingly, there is no sign of exhaustion of specific antibodies even under extreme conditions, which makes it highly unlikely that a smoker can overcome the protective effect of the vaccine by smoking more. Finally, the high titers of specific antibodies after 1 year let us hope that booster vaccinations are probably only necessary in intervals of years.

To assess the molecular epidemiology of HIV-1 in Republic of Congo (Congo), we investigated 29 HIV-1s obtained from 82 Congolese AIDS and ARC patients in 1996 and 1997. Part of the env region including the V3 loop was phylogenetically analyzed. The genotypes observed were varied: of 29 specimens, 12 (41 %) were subtype A, 1 (3%) was subtype D, 6 (21%) were subtype G, 6 (21%) were subtype H, 2 (7%) were subtype J, and 2 (7%) could not be classified as any known subtypes (U, unclassified). The heterogeneous profile of HIV-1 infection was different from the profiles of neighboring Central African countries. These data show that subtypes G and H as well as subtype A were circulating with high prevalence. The fact that new genetic subtypes (J and U) are circulating indicates a need for a greater surveillance for these subtypes both in Congo as well as in other parts of the world.

No abstract

To investigate the HIV-1 subtypes prevalent in the Republic of Congo, we isolated 28 HIV-1 strains from Congolese AIDS patients in 1996 and 1997, and analyzed them phylogenetically. Phylogenetic analysis based on part of the 5' tat-env (vpu) and env sequences revealed that only 13 (46.4%) of the 28 isolates belonged to the same subtype in the vpu tree as in the env tree; the remaining 15 (53.6%) strains showed discordant subtypes between vpu and env with 6 different profiles; that is, 1 A/A (vpu/env), 1 D/D, 5 G/G, 4 H/H, 2 unclassified (U)/U, 9 G/A, 2 G/H, 1 G/J, 1 H/G, 1 U/A, and 1 U/J. Thus, 9 of the 15 discordant HIV-1s were of the G/A (vpu/env) type, and did not form any subcluster within the subtype G lineage in the vpu-based phylogenetic tree. In addition, CRF02_AG (IbNG), which is a G/A (vpu/env) type, was not found in the Republic of Congo. These data suggest that the majority of HIV-1 subtypes circulating in the Republic of Congo have mosaic structures and may have been derived from independent recombinational events.

Mouse mammary tumor virus (MMTV) infects the host via mucosal surfaces and exploits the host immune system for systemic spread and chronic infection. We have tested a neutralizing rat monoclonal antibody specific for the retroviral envelope glycoprotein gp52 for its efficiency in preventing acute and chronic mucosal and systemic infection. The antibody completely inhibits the superantigen response and chronic viral infection following systemic or nasal infection. Surprisingly however, the antibody only partially inhibits the early infection of antigen-presenting cells in the draining lymph node. Despite this initially inefficient protection from infection, superantigen-specific B-and T-cell responses and systemic viral spread are abolished, leading to complete clearance of the retroviral infection and hence interruption of the viral life cycle. In conclusion, systemic neutralizing monoclonal antibodies can provide an efficient protection against chronic retroviral amplification and persistence.The retrovirus mouse mammary tumor virus (MMTV) is transmitted from infected mothers to offspring via milk during the first 2 weeks after birth. MMTV targets three major cell types for infection: dendritic cells (DC) (33, 42) and B lymphocytes (9, 22) early in infection and epithelial cells of exocrine secretory organs later on (for a review see reference 31). Once MMTV has crossed the mucosa it infects DC and B cells in the Peyer's patches (PP) before spreading to peripheral organs (27). Chronic infection of the mammary gland leads to viral transmission via milk and to mammary tumor development after retroviral insertion next to proto-oncogenes (34). Adult mice can be chronically infected by subcutaneous (s.c.) injection (23) or by nasal administration of the virus (44). After entry into the cell, viral RNA is reverse transcribed and the resulting viral DNA is integrated into the genome in target DC and B cells. This leads to expression of a viral superantigen (SAg) at the cell surface (22). Oral, s.c., and nasal routes of infection proceed with similar kinetics, which are dominated by efficient priming of a SAg T-cell response via an interaction between infected B cells and DC-primed SAg-reactive cognate T cells. SAg-activated T cells are slowly deleted from the peripheral T-cell repertoire. This deletion represents one of the most sensitive readouts for chronic infection and systemic spread of MMTV. While the virus persists in all lymphoid and nonlymphoid organs, MMTV establishes a chronic immune response with germinal centers, persisting antigen (Ag), and virus-specific B and T cells only in the draining lymph node (LN). This leads to a weak life-long neutralizing antibody (Ab) response against the viral envelope (Env) protein gp52 (32). Although in susceptible mice this chronic Ab response is unable to clear the virus infection, resistant mouse strains such as I/LnJ have evolved a strong neutralizing Ab response that controls chronic infection and prevents infection of the progeny (39). This is in agreement with the r...