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    Abstract:
    Dimeric derivatives (compounds 7 to 9) of the influenza virus neuraminidase inhibitor zanamivir (compound 2), which have linking groups of 14 to 18 atoms in length, are approximately 100-fold more potent inhibitors of influenza virus replication in vitro and in vivo than zanamivir. The observed optimum linker length of 18 to 22 A, together with observations that the dimers cause aggregation of isolated neuraminidase tetramers and whole virus, indicate that the dimers benefit from multivalent binding via intertetramer and intervirion linkages. The outstanding long-lasting protective activities shown by compounds 8 and 9 in mouse influenza infectivity experiments and the extremely long residence times observed in the lungs of rats suggest that a single low dose of a dimer would provide effective treatment and prophylaxis for influenza virus infections.
    Keywords:
    Zanamivir
    Neuraminidase inhibitor
    Infectivity
    Sialidase
    Dimeric derivatives (compounds 7 to 9) of the influenza virus neuraminidase inhibitor zanamivir (compound 2), which have linking groups of 14 to 18 atoms in length, are approximately 100-fold more potent inhibitors of influenza virus replication in vitro and in vivo than zanamivir. The observed optimum linker length of 18 to 22 A, together with observations that the dimers cause aggregation of isolated neuraminidase tetramers and whole virus, indicate that the dimers benefit from multivalent binding via intertetramer and intervirion linkages. The outstanding long-lasting protective activities shown by compounds 8 and 9 in mouse influenza infectivity experiments and the extremely long residence times observed in the lungs of rats suggest that a single low dose of a dimer would provide effective treatment and prophylaxis for influenza virus infections.
    Zanamivir
    Neuraminidase inhibitor
    Infectivity
    Sialidase
    For many years, antiviral treatment of influenza has consisted of monotherapy with a neuraminidase inhibitor. The Food and Drug Administration (FDA) approved the neuraminidase inhibitors oseltamivir (oral administration) and zanamivir (oral inhalation) in 1999 and peramivir (intravenous administration) in late 2014. These drugs work by binding to the viral neuraminidase protein and interfering with the release of influenza virus particles from infected respiratory tract cells. Neuraminidase inhibitors are FDA-approved for the treatment of uncomplicated influenza within 2 days after onset in outpatients, on the basis of randomized, controlled trials, but they are also recommended for the treatment of patients with . . .
    Zanamivir
    Neuraminidase inhibitor
    Oseltamivir
    Citations (11)
    Although influenza virus resistance to the neuraminidase inhibitor zanamivir is reported less frequently than is resistance to the neuraminidase inhibitor oseltamivir in clinical settings, it is unknown whether this difference is due to the limited use of zanamivir or to an inherent property of the drug. We therefore compared the prevalence of drug-resistant viruses and virus shedding in seasonal influenza virus-infected children treated with either oseltamivir or zanamivir.Clinical specimens (throat or nasal swab) were collected from a total of 144 pediatric influenza patients during the 2005-2006, 2006-2007, 2007-2008, and 2008-2009 influenza seasons. Neuraminidase inhibitor-resistant mutants were detected among the isolated viruses by sequencing the viral hemagglutinin and neuraminidase genes. Sensitivity of the viruses to neuraminidase inhibitors was tested by neuraminidase inhibition assay.In oseltamivir- or zanamivir-treated influenza patients who were statistically comparable in their age distribution, vaccination history, and type or subtype of virus isolates, the virus-shedding period in zanamivir-treated patients was significantly shorter than that in oseltamivir-treated patients. Furthermore, the frequency of zanamivir-resistant viruses was significantly lower than that of oseltamivir-resistant viruses.In comparison with treatment with oseltamivir, treatment of pediatric patients with zanamivir resulted in the emergence of fewer drug-resistant influenza viruses and a shorter virus-shedding period. We conclude that zanamivir shows promise as a better therapy for pediatric influenza patients.
    Zanamivir
    Oseltamivir
    Neuraminidase inhibitor
    Viral Shedding
    Citations (50)
    Two hundred and forty-five human influenza A and B viruses isolated in Australia between 1996 and 2003 were tested for their sensitivity to the NA inhibitor drugs, zanamivir and oseltamivir using a fluorescence-based neuraminidase inhibition assay. Based on mean IC50 values, influenza A viruses (with neuraminidase subtypes N1 and N2) were more sensitive to both the NA inhibitors than were influenza B strains. Influenza A viruses with a N1 subtype and influenza B strains both demonstrated a greater sensitivity to zanamivir than to oseltamivir carboxylate, whereas influenza A strains with a N2 subtype were more susceptible to oseltamivir carboxylate. A comparison of IC50 values for viruses isolated before and after the release of the NA inhibitors in Australia, found there was no significant difference in the sensitivity of strains to either neuraminidase inhibitor and none of the isolates tested showed clinically significant resistance.
    Zanamivir
    Oseltamivir
    Neuraminidase inhibitor
    IC50
    Human influenza
    Sialidase
    Citations (12)
    To assess the extent of susceptibility to the four neuraminidase inhibitors (NAIs) approved in Japan of the epidemic viruses in the 2022–23 influenza season in Japan, we measured the 50 % inhibitory concentration (IC50) of oseltamivir, zanamivir, peramivir, and laninamivir in influenza virus isolates from patients. Viral isolation was done with specimens obtained prior to and after treatment, and the type/subtype was determined by RT-PCR using type- and subtype-specific primers. The IC50 was determined by a neuraminidase inhibition assay using a fluorescent substrate. Virus isolates, one A(H1N1)pdm09 and 74 A(H3N2), were measured in the 2022–23 season. The geometric mean IC50s of the 74 A(H3N2) isolated prior to treatment were 0.78 nM, 0.66 nM, 2.08 nM, and 2.85 nM for oseltamivir, peramivir, zanamivir, and laninamivir, respectively, comparable to those of the previous ten studied seasons. No A(H3N2) with highly reduced sensitivity to any of the NAIs was found in the 2022-23 season prior to or after drug administration. These results indicate that the sensitivity to these four commonly used NAIs has been maintained, at least for A(H3N2), in the 2022–23 influenza season in Japan, after the 2020–21 and 2021–22 seasons when the prevalence of influenza was extremely low.
    Zanamivir
    Neuraminidase inhibitor
    Oseltamivir
    IC50
    Influenza season
    ABSTRACT An oral prodrug of GS 4071, a potent and selective inhibitor of influenza neuraminidases, is currently under clinical development for the treatment and prophylaxis of influenza virus infections in humans. To investigate the potential development of resistance during the clinical use of this compound, variants of the human influenza A/Victoria/3/75 (H3N2) virus with reduced susceptibility to the neuraminidase inhibitor GS 4071 were selected in vitro by passaging the virus in MDCK cells in the presence of inhibitor. After eight passages, variants containing two amino acid substitutions in the hemagglutinin (A28T in HA1 and R124M in HA2) but no changes in the neuraminidase were isolated. These variants exhibited a 10-fold reduction in susceptibility to GS 4071 and zanamivir (GG167) in an in vitro plaque reduction assay. After 12 passages, a second variant containing these hemagglutinin mutations and a Lys substitution for the conserved Arg292 of the neuraminidase was isolated. The mutant neuraminidase enzyme exhibited high-level (30,000-fold) resistance to GS 4071, but only moderate (30-fold) resistance to zanamivir and 4-amino-Neu5Ac2en, the amino analog of zanamivir. The mutant enzyme had weaker affinity for the fluorogenic substrate 2′-(4-methylumbelliferyl)-α- d - N -acetylneuraminic acid and lower enzymatic activity compared to the wild-type enzyme. The viral variant containing the mutant neuraminidase did not replicate as well as the wild-type virus in culture and was 10,000-fold less infectious than the wild-type virus in a mouse model. These results suggest that although the R292K neuraminidase mutation confers high-level resistance to GS 4071 in vitro, its effect on viral virulence is likely to render this mutation of limited clinical significance.
    Zanamivir
    Neuraminidase inhibitor
    Influenzavirus B
    Wild type
    Citations (150)
    We have recently reported an influenza virus neuraminidase inhibitor, RWJ-270201 (BCX-1812), a novel cyclopentane derivative discovered through structure-based drug design. In this paper, we compare the potency of three compounds, RWJ-270201, oseltamivir, and zanamivir, against neuraminidase enzymes from various subtypes of influenza. RWJ-270201 effectively inhibited all tested influenza A and influenza B neuraminidases in vitro, with 50% inhibitory concentrations of 0.09 to 1.4 nM for influenza A neuraminidases and 0.6 to 11 nM for influenza B neuraminidases. These values were comparable to or lower than those for oseltamivir carboxylate (GS4071) and zanamivir (GG167). RWJ-270201 demonstrated excellent selectivity (>10,000-fold) for influenza virus neuraminidase over mammalian, bacterial, or other viral neuraminidases. Oral administration of a dosage of 1 mg/kg of body weight/day of RWJ-270201 for 5 days (beginning 4 h preinfection) showed efficacy in the murine model of influenza virus infection as determined by lethality and weight loss protection. RWJ-270201 administered intranasally at 0.01 mg/kg/day in the murine influenza model demonstrated complete protection against lethality, whereas oseltamivir carboxylate and zanamivir at the same dose demonstrated only partial protection. In the delayed-treatment murine influenza model, oral administration of a 10-mg/kg/day dose of RWJ-270201 or oseltamivir (GS4104, a prodrug of GS4071) at 24 h postinfection showed significant protection against lethality (P < 0.001 versus control). However, when the treatment was delayed for 48 h, no significant protection was observed in either drug group. No drug-related toxicity was observed in mice receiving 100 mg/kg/day of RWJ-270201 for 5 days. These efficacy and safety profiles justify further consideration of RWJ-270201 for the treatment and prevention of human influenza.
    Zanamivir
    Oseltamivir
    Neuraminidase inhibitor
    Neuraminidase inhibitors (NAIs) are recommended for influenza treatment and prevention worldwide. The most widely prescribed NAI is oral oseltamivir, while inhaled zanamivir is less commonly used. Using phenotypic neuraminidase (NA) enzymatic assays and molecular modeling approaches, we examined the ability of the investigational orally-dosed NAI AV5080 to inhibit viruses of the influenza A(H1N1)pdm09, A(H3N2), A(H5N1), and A(H7N9) subtypes and the influenza B/Victoria- and B/Yamagata-lineages containing NA substitutions conferring oseltamivir or zanamivir resistance including: NA-R292K, NA-E119G/V, NA-H274Y, NA-I122L/N, and NA-R150K. Broadly, AV5080 showed enhanced in vitro efficacy when compared with oseltamivir and/or zanamivir. Reduced AV5080 inhibition was determined for influenza A viruses with NA-E119G and NA-R292K, and for B/Victoria-lineage viruses with NA-I122N/L and B/Yamagata-lineage virus with NA-R150K. Molecular modeling suggested loss of the short hydrogen bond to the carboxyl group of AV5080 affected inhibition of NA-R292K viruses, whereas loss of the salt bridge with the guanidine group of AV5080 affected inhibition of NA-E119G. The resistance profiles and predicted binding modes of AV5080 and zanamivir are most similar, but dissimilar to those of oseltamivir, in part because of a guanidine moiety compensatory binding effect. Overall, our data suggests that AV5080 is a promising orally-dosed NAI that exhibited similar or superior in vitro efficacy against viruses with reduced or highly reduced inhibition phenotypes with respect to currently approved NAIs.
    Neuraminidase inhibitor
    Influenzavirus B