Despite advances in antiretroviral therapy that have revolutionized HIV disease management, effective control of the HIV infection pandemic remains elusive. Beyond the classic non-B endemic areas, HIV-1 non-B subtype infections are sharply increasing in previous subtype B homogeneous areas such as Europe and North America. As already known, several studies have shown that, among non-B subtypes, subtypes C and D were found to be more aggressive in terms of disease progression. Luckily, the response to antiretrovirals against HIV-1 seems to be similar among different subtypes, but these results are mainly based on small or poorly designed studies. On the other hand, differences in rates of acquisition of resistance among non-B subtypes are already being observed. This different propensity, beyond the type of treatment regimens used, as well as access to viral load testing in non-B endemic areas seems to be due to HIV-1 clade specific peculiarities. Indeed, some non-B subtypes are proved to be more prone to develop resistance compared to B subtype. This phenomenon can be related to the presence of subtype-specific polymorphisms, different codon usage, and/or subtype-specific RNA templates. This review aims to provide a complete picture of HIV-1 genetic diversity and its implications for HIV-1 disease spread, effectiveness of therapies, and drug resistance development.

We compared anti-GM1 IgM antibody titers in patients with various neurologic diseases and in normal subjects. We found increased titers in patients with lower motor neuron disease, sensorimotor neuropathy, or motor neuropathy with or without multifocal conduction block. In patients with other diseases, titers are similar to those in normal individuals, suggesting that anti-GM1 antibody levels are not increased nonspecifically after neural injury or inflammatory diseases. Anti-GM1 antibodies in many of the patients occur as monoclonal gammopathies, predominantly of lambda light-chain type, but the antibodies are sometimes polyclonal with normal or increased serum IgM concentrations. Most of the anti-GM1 antibodies appear to react with the Gal(beta 1-3)GalNAc epitope which is shared with asialo-GM1 and GD1b, but in some patients the antibodies are more specific for GM1 and associated with motor neuropathy. Patients with motor or sensorimotor peripheral neuropathy or lower motor neuron disease should be tested for anti-GM1 antibodies or anti-Gal(beta 1-3)GalNAc antibodies, as therapeutic reduction in antibody concentrations was reported to result in clinical improvement in some patients.

Skeletal muscle changes were evaluated in patients suffering from hemiparesis after stroke. Concentric needle EMG and single fiber EMG of the paretic gastrocnemius medialis muscle were performed. Maximal amplitude of H, T and M responses in calf muscles of both the affected and the unaffected sides were determined by usual electrophysiological techniques. Muscle biopsy of the lateral gastrocnemius muscle of the affected side was performed to determine the distribution of fiber types and fiber sizes. Fibrillation activity and positive sharp waves occurred in paretic muscles in patients with more recent hemiparesis while the duration of motor unit potentials was prolonged in patients with long-lasting disease. The H/M ratio was increased on the paretic side. The percentage of type 1 fibers was augmented in most patients with normal mean diameter and low atrophy factor. The percentage of type 2 fibers was reduced with decreased mean diameters and with a high atrophy factor. Such changes may be related to inactivity or transsynaptic degeneration of type 2 motoneurons as a consequence of the interruption of the corticospinal tract. Increased percentage of type 1 fibers may be due to a collateral reinnervation process or a motor unit type transformation.

Increased titers of antibodies to GM1 ganglioside in humans are associated with lower motor neuron disease and predominantly motor neuropathy with or without conduction block. To investigate the possible mechanism of these antibodies, we injected the serum of a patient with anti-GM1 antibodies who had motor neuron disease and multifocal motor conduction block, into rat sciatic nerve. When injected with fresh human complement, the serum-induced conduction block with temporal dispersion and deposits of immunoglobulin were detected at the nodes of Ranvier. Electron microscopic studies revealed demyelination in 6.5% of the fibers. After preabsorption with GM1, the serum had no effect, suggesting that the anti-GM1 antibodies were responsible for the conduction abnormalities.

Background: We tested whether pre-HAART viraemia affects the achievement and maintenance of virological success in HIV-1-infected patients starting modern firstline therapies. Methods: A total of 1,430 patients starting their first HAART (genotype-tailored) in 2008 (median; IQR: 2006-2009) were grouped according to levels of pre-HAART viraemia (≤30,000, 30,001-100,000, 100,001-300,000, 300,001-500,000 and >500,000 copies/ml). The impact of pre-therapy viraemia on the time to virological success (viraemia ≤50 copies/ml) and on the time to virological rebound (first of two consecutive viraemia values >50 copies/ml after virological success) were evaluated by Kaplan-Meier curves and Cox regression analyses. Results: Median pre-HAART viraemia was 5.1 log 10 copies/ml (IQR 4.5-5.5), and 53% of patients had viraemia >100,000 copies/ml. By week 48, the prevalence of patients reaching virological success was >90% in all pre-HAART viraemia ranges, with the only exception of range >500,000 copies/ml (virological success =83%; P<0.001). Higher pre-HAART viraemia was tightly correlated with longer median time to achieve virological success. Cox multivariable estimates confirmed this result: patients with pre-HAART viraemia >500,000 copies/ml showed the lowest hazard of virological undetectability after adjusting for age, gender, pre-HAART CD4 + T-cell count, transmitted drug resistance, calendar year and third drug administered (adjusted hazard ratio [95% CI]: 0.27 [0.21, 0.35]; P<0.001). Pre-HAART viraemia >500,000 copies/ml was also associated with higher probability of virological rebound compared with patients belonging to lower viraemia strata at weeks 4, 12 and 24 (P=0.050). Conclusions: At the time of modern HAART, and even though an average >90% of virological success, high pre-HAART viraemia remains an independent factor associated with delayed and decreased virological success. Patients starting HAART with >500,000 copies/ml represent a significant population that may deserve special attention.HAART has significantly extended the time to development of AIDS and to death in HIV-infected individuals [1,2]. Its efficacy in suppression of plasma HIV-1 RNA to undetectable levels, and in increasing CD4 + T-cell count, is well documented in several clinical trials [3][4][5][6].Despite years of great progress in treating AIDS, however, in some patients starting their first treatment; the effectiveness of HAART is still not sufficient, with consequent virological failures [7][8][9]. These failures can be caused by several factors, such as drug potency, drug

The Omicron variant of concern (VOC) has a peculiar spectrum of mutations characterized by the acquisition of mutations or deletions rarely detected in previously identified variants, particularly in the spike glycoprotein. Such mutations, mostly residing in the receptor-binding domain, could play a pivotal role in enhancing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infectivity (by increasing binding affinity for ACE2), jeopardizing spike recognition by therapeutic and vaccine-induced antibodies and causing diagnostic assay failure.

Antibodies to GM1 or Gal(beta 1-3)GalNAc are associated with motor or sensorimotor neuropathy and with motor neuron disease. To investigate the role of these antibodies in the neurological disorder, rabbits were immunized with GM1 or with Gal(beta 1-3)GalNAc-BSA, and studied serologically, electrophysiologically and pathologically. Development of antibodies to the immunizing antigens was associated with a fall in the ratio of the amplitudes of the compound muscle action potential evoked by proximal versus distal stimulation of the sciatic nerve. Pathological studies revealed mild axonal degeneration and immunoglobulin deposits at the nodes of Ranvier in peripheral nerve, resembling those reported in a patient with motor neuropathy, motor conduction block and anti-GM1 antibodies. These studies provide evidence that anti-GM1 or anti-Gal(beta 1-3)GalNAc antibodies cause conduction abnormalities and indicate that the antibodies may exert their effect, in part, by binding at the nodes of Ranvier in peripheral nerve.

Increased titers of anti-GM1 antibodies have been associated with motor neuron disease and motor neuropathy with or without conduction block. To investigate the pathogenetic role of anti-GM1 antibodies we injected into rat tibial nerves sera from patients with multifocal motor neuropathy and conduction block (MMN) or progressive spinal muscular atrophy (PMA), both presenting anti-GM1 antibodies. Sera of patients with MMN produced reduction of amplitude and dispersion of compound muscle action potential from proximal stimulation. Morphometry revealed demyelination in 6.2% of fibers. Sera of patients with PMA did not produce clear-cut electrophysiological or morphological changes. Differential effects of sera from patients presenting high-titer anti-GM1 antibodies, but with distinct clinical syndromes, might depend on differences in anti-GM1 antibody affinity, valency, or ability to fix complement. Alternatively, circulating factors other than, or in addition to, anti-GM1 antibodies present in sera of patients with MMN, but not of PMA patients, might be responsible for conduction abnormalities and reproduce them after passive transfer.