Anti-Influenza Drugs: The Development of Sialidase Inhibitors

Itzstein, Mark von; Thomson, Robin Joy

doi:10.1007/978-3-540-79086-0_5

Cited by 50 publications

(52 citation statements)

References 172 publications

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“…Modifications at the C-5 position of Neu2en5Ac were the first improved in vitro NA inhibitors [9]. However, neither Neu2en5Ac nor the modified compound has an in vivo inhibition activity against IAV, possibly due to their rapid clearance [9]. The presence of Neu2enAc in natural mucins might indicate that hosts also secrete their own NA-inhibitors.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Influenza A penetrates host mucus by cleaving sialic acids with neuraminidase

Cohen

Zhang

Senaati

et al. 2013

Virol J

241

224

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BackgroundInfluenza A virus (IAV) neuraminidase (NA) cleaves sialic acids (Sias) from glycans. Inhibiting NA with oseltamivir suppresses both viral infection, and viral release from cultured human airway epithelial cells. The role of NA in viral exit is well established: it releases budding virions by cleaving Sias from glycoconjugates on infected cells and progeny virions. The role of NA in viral entry remains unclear. Host respiratory epithelia secrete a mucus layer rich in heavily sialylated glycoproteins; these could inhibit viral entry by mimicking sialylated receptors on the cell surface. It has been suggested that NA allows influenza to penetrate the mucus by cleaving these sialylated decoys, but the exact mechanism is not yet established.MethodsWe tested IAV interaction with secreted mucus using frozen human trachea/bronchus tissue sections, and bead-bound purified human salivary mucins (HSM) and purified porcine submaxillary mucins (PSM). The protective effect of mucus was analyzed using MDCK cells coated with purified HSM and PSM with known Sia content. Oseltamivir was used to inhibit NA activity, and the fluorescent reporter substrate, 4MU-Neu5Ac, was used to quantify NA activity.ResultsIAV binds to the secreted mucus layer of frozen human trachea/bronchus tissues in a Sia dependent manner. HSM inhibition of IAV infection is Sia dose-dependent, but PSM cannot inhibit infection of underlying cells. HSM competitively inhibits NA cleavage of 4MU-Neu5Ac, reporter substrate. Human IAV effectively cleaves Sias from HSM but not from PSM, and binds to HSM but not to PSM.ConclusionIAV interacts with human mucus on frozen tissue sections and mucus-coated beads. Inhibition of IAV infection by sialylated human mucus is dose-dependent, and enhanced when NA is inhibited with oseltamivir. Thus NA cleaves sialylated decoys during initial stages of infection. Understanding IAV interactions with host mucins is a promising new avenue for drug development.

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Section: Discussionmentioning

confidence: 99%

“…NA inhibitors such as oseltamivir inhibit viral release by preventing the cleavage of Sias specifically [9]. It has also been shown that NA inhibition with oseltamivir carboxylate suppresses IAV infection of cultured human airway epithelium (HTBE) [10].…”

Section: Introductionmentioning

confidence: 99%

Influenza A penetrates host mucus by cleaving sialic acids with neuraminidase

Cohen

Zhang

Senaati

et al. 2013

Virol J

241

224

View full text Add to dashboard Cite

show abstract

“…Consequently, synthetic neuraminidase inhibitors have been shown to suppress influenza virus dissemination (60). To test whether NA antibodies would also interfere with virus spread, MDCK cells were infected with A/chicken/Yamaguchi/7/04 (H5N1) at an MOI of 0.0025 TCID 50 / cell.…”

Section: Na Antibodies Inhibit Virus Spread In Vitromentioning

confidence: 99%

Biological and Protective Properties of Immune Sera Directed to the Influenza Virus Neuraminidase

Halbherr¹,

Ludersdorfer²,

Ricklin³

et al. 2015

J Virol

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The envelope of influenza A viruses contains two large antigens, hemagglutinin (HA) and neuraminidase (NA). Conventional influenza virus vaccines induce neutralizing antibodies that are predominantly directed to the HA globular head, a domain that is subject to extensive antigenic drift. Antibodies directed to NA are induced at much lower levels, probably as a consequence of the immunodominance of the HA antigen. Although antibodies to NA may affect virus release by inhibiting the sialidase function of the glycoprotein, the antigen has been largely neglected in past vaccine design. In this study, we characterized the protective properties of monospecific immune sera that were generated by vaccination with recombinant RNA replicon particles encoding NA. These immune sera inhibited hemagglutination in an NA subtype-specific and HA subtype-independent manner and interfered with infection of MDCK cells. In addition, they inhibited the sialidase activities of various influenza viruses of the same and even different NA subtypes. With this, the anti-NA immune sera inhibited the spread of H5N1 highly pathogenic avian influenza virus and HA/NA-pseudotyped viruses in MDCK cells in a concentration-dependent manner. When chickens were immunized with NA recombinant replicon particles and subsequently infected with low-pathogenic avian influenza virus, inflammatory serum markers were significantly reduced and virus shedding was limited or eliminated. These findings suggest that NA antibodies can inhibit virus dissemination by interfering with both virus attachment and egress. Our results underline the potential of high-quality NA antibodies for controlling influenza virus replication and place emphasis on NA as a vaccine antigen. IMPORTANCEThe neuraminidase of influenza A viruses is a sialidase that acts as a receptor-destroying enzyme facilitating the release of progeny virus from infected cells. Here, we demonstrate that monospecific anti-NA immune sera inhibited not only sialidase activity, but also influenza virus hemagglutination and infection of MDCK cells, suggesting that NA antibodies can interfere with virus attachment. Inhibition of both processes, virus release and virus binding, may explain why NA antibodies efficiently blocked virus dissemination in vitro and in vivo. Anti-NA immune sera showed broader reactivity than anti-HA sera in hemagglutination inhibition tests and demonstrated cross-subtype activity in sialidase inhibition tests. These remarkable features of NA antibodies highlight the importance of the NA antigen for the development of next-generation influenza virus vaccines.

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“…30–32 The available X-ray crystal structures of viral neuraminidases, 30 bacterial sialidases, 33–35 and a more recent human cytosolic sialidase NEU2 36 provide great opportunities for rational sialidase inhibitor design.…”

Section: Introductionmentioning

confidence: 99%

Identifying selective inhibitors against the human cytosolic sialidase NEU2 by substrate specificity studies

Cao

et al. 2011

Mol. BioSyst.

102

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Aberrant expression of human sialidases has been shown to associate with various pathological conditions. Despite the effort in sialidase inhibitor design, less attention has been paid to designing specific inhibitors against human sialidases and characterizing the substrate specificity of different sialidases regarding diverse terminal sialic acid forms and sialyl linkages. This is mainly due to the lack of sialoside probes and efficient screening methods, as well as limited access to human sialidases. Low cellular expression level of human sialidase NEU2 hampers its functional and inhibitory studies. Here we report the successful cloning and expression of human sialidase NEU2 in E. coli. About 11 mg of soluble active NEU2 was routinely obtained from 1 L of E. coli cell culture. Substrate specificity studies of the recombinant human NEU2 using twenty para-nitrophenol (pNP)-tagged α2–3- or α2–6-linked sialyl galactosides containing different terminal sialic acid forms including common N-acetylneuraminic acid (Neu5Ac), non-human N-glycolylneuraminic acid (Neu5Gc), 2-keto-3-deoxy-D-glycero-D-galacto-nonulosonic acid (Kdn), or their C5-derivatives in a microtiter plate-based high-throughput colorimetric assay identified a unique structural feature specifically recognized by the human NEU2 but not two bacterial sialidases. The results obtained from substrate specificity studies were used to guide the design of a sialidase inhibitor that was selective against human NEU2. The selectivity of the inhibitor was revealed by the comparison of sialidase crystal structures and inhibitor docking studies.

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Anti-Influenza Drugs: The Development of Sialidase Inhibitors

Cited by 50 publications

References 172 publications

Influenza A penetrates host mucus by cleaving sialic acids with neuraminidase

Influenza A penetrates host mucus by cleaving sialic acids with neuraminidase

Biological and Protective Properties of Immune Sera Directed to the Influenza Virus Neuraminidase

Identifying selective inhibitors against the human cytosolic sialidase NEU2 by substrate specificity studies

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