Progressive multifocal leukoencephalopathy in HIV-1 infection

Abstract

Progressive multifocal leukoencephalopathy (PML) caused by the polyomavirus, JC virus (JCV), is one of the most dreaded complications of HIV-1 infection. Unlike other opportunistic infections, PML may present while blood CD4+ T cells remain above AIDS-defining levels and while patients receive combined antiretroviral therapy (cART), either shortly after starting or, more rarely, during chronic successful treatment. PML can be suspected by typical presentation with focal neurological deficits and corresponding demyelinating lesions at magnetic resonance imaging (MRI), while definitive diagnosis requires identification of JCV in cerebrospinal fluid (CSF) or brain tissue. While there is no specific treatment, reversal of immunosuppression by cART leads to clinical and MRI stabilization in 50-60% of PML patients and JCV clearance from CSF. A proportion of cART-treated patients develop inflammatory lesions, which may either accompany a favorable outcome or associate with clinical worsening. The reasons for variability in PML natural history and treatment responses are largely undefined, and more specific and rational approaches to management are sorely needed.