S133 Resistance to anti-retroviral drugs

,932

Symposia

-

IS131

ing of these mechanisms may offer new therapeutic modalities in the future.

Dermatology,

University

of Bologna,

A vaccine for HIV?

Frances Gotch ’ , Stephen McAdam *, James Whitworth 3. ’ Chelsea RadclifSe

I S128 Fusarium onychomycosis B.M. Piraccini, C. Stinchi, E. Ghetti, A. Tosti. Department

HIV - Virology

of

Italy

Although Fusarium sp. are widely present in the soil, toenail invasion by Fusarium oxysporum is quite uncommon. In immunosuppressed patients, onychomycosis due to Fusarium sp. may be dangerous since it can be a possible portal of entry for a systemic infection. The clinical appearance of Fusarium onychomycosis is typical and consists of acute paronychia associated with proximal or total leukonychia of the affected nails. Treatment of Fusarium onychomycosis is not always successful. Nail avulsion followed by application of topical antifungals is in our experience the most effective treatment.

HIV - Virology ElS129 Human T cell leukaemia viruses: Origins,

and Westminster Hospital, Onford,

Hospital, London, UK, *John USA, 3U. VR.I. Entebbe, Uganda

8,500 persons/day are infected with HIV, 90% of whom live in developing countries. It would cost 300 billion dollars to treat all HIV infected individuals in the world with modern, potent, antiretroviral drugs. This is clearly not feasible and there is an urgent need to develop a vaccine for HIV. Such a prophylactic vaccine will need to be effective and safe; and to induce cross-reactive immune responses in order to protect at-risk individuals from infection with all the different subtypes or clades of virus to which they may be exposed. There is an increasing body of evidence to suggest that cytotoxic T lymphocytes play a crucial role in the control of HIV throughout infection, and may be able to offer some degree of protection. We propose therefore that a vaccine for HIV should generate high levels of virus specific CTL prior to virus exposure. We have conducted experiments to evaluate whether a vaccine based on a single well-characterised clade of virus (B clade) would be expected to induce sufficient cross-reactive cellular immune responses to offer protection from infection with other clades of HIV.1 such as A, C and D clade which predominate in Sub-Saharan Africa where vaccines are most urgently needed.

epidemiology and clinical significance

William W. Hall. Department University

College

Dublin,

of Medical Microbiology, Dublin, Ireland

.

The human T leukaemia viruses, type I (HTLV-I) and type II (Type II) are members of a family of mammalian retroviruses that have similar biological properties and a tropism for T lymphocytes. HTLV-I is endemic in a number of well-defined geographic areas, where infection is associated with adult T cell leukaemia (ATL), a malignancy of mature T lymphocytes, a chronic encephalomyelopathy known both as HTLV-I-associated myelopathy and tropical spastic paraparesis (HAMKSP), and a number of other inflammatory disorders. HTLV-II infection has been shown to be endemic in a number of American Indian populations, and high rates of infection have been documented in intravenous drug abusers (IVDAs) in urban areas throughout the world. In the studies to be presented the focus will be on HTLV-II infections. Specifically the epidemiology, the molecular properties of the virus, and the clinical and immunological features of infection will be described. We will describe the isolation and compare the properties of a new molecular subtype of the virus to those of the established subtypes and we will also provide evidence that HTLV-II infection, like HTLV-I, is associated with neurological disease. Preliminary studies to test the feasibility of vaccination to prevent HTLV-I and HTLV-II infections will also be described.

IS132

Immune evasion by the human immunodeflclency virus

R.E. Philips. University

of Oxford,

UK

The natural history infection with HIV suggests that this virus is highly adept at immune evasion. In the earliest phases of infection there is a high viraemia which declines as HIV specific cytotoxic T lymphocytes become detectable. The viraemia which persists after the onset of this immune response consists of viral mutants which have epitope mutations. Many of these mutant epitopes are not recognised by CTL. During the long asymptomatic period HIV CTL are readily detected. In this phase there is a complex interaction between this immune response and the virus. Some mutants do not bind to HLA molecules but some which do act as antagonists. Progression of the infection with further escalation of the viraemia is associated with a decline in HIV specific CTL activity and the emergence of clear cut escape mutants. In HLAB27 individuals these mutations are in crucial sites within the epitope which bind the antigen to HLA molecules. These antigens do not arrive on the cell surface and so provide a superb means of immune escape. CD8 positive CTL also secrete chemokines capable of blocking HIV cell entry. Secretion of these chemokines is antigen dependent and variation in the virus is also able to modulate the secretion of these chemokines and so diminish their effectiveness.

I S130 Anti-retrovlral therapy: Current status and

future prospects

Jonathan Weber. England Abstract not available.

I S133 Resistance to anti-retroviral drugs Charles Boucher. The Netherlands Abstract not available.