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Relationship: 2978

Title

A descriptive phrase which clearly defines the two KEs being considered and the sequential relationship between them (i.e., which is upstream, and which is downstream). More help

IAV binds receptor leads to IAV cell entry

Upstream event

The causing Key Event (KE) in a Key Event Relationship (KER). More help

IAV binds receptor

Downstream event

The responding Key Event (KE) in a Key Event Relationship (KER). More help

IAV cell entry

Key Event Relationship Overview

The utility of AOPs for regulatory application is defined, to a large extent, by the confidence and precision with which they facilitate extrapolation of data measured at low levels of biological organisation to predicted outcomes at higher levels of organisation and the extent to which they can link biological effect measurements to their specific causes.Within the AOP framework, the predictive relationships that facilitate extrapolation are represented by the KERs. Consequently, the overall WoE for an AOP is a reflection in part, of the level of confidence in the underlying series of KERs it encompasses. Therefore, describing the KERs in an AOP involves assembling and organising the types of information and evidence that defines the scientific basis for inferring the probable change in, or state of, a downstream KE from the known or measured state of an upstream KE. More help

AOPs Referencing Relationship

AOP Name	Adjacency	Weight of Evidence	Quantitative Understanding	Point of Contact	Author Status	OECD Status
Binding of Influenza A Virus (IAV) to Sialic Acid Glycan Receptor leads to viral infection proliferation	adjacent	High	Not Specified	Jessica Resnick (send email)	Under development: Not open for comment. Do not cite

Taxonomic Applicability

Latin or common names of a species or broader taxonomic grouping (e.g., class, order, family) that help to define the biological applicability domain of the KER.In general, this will be dictated by the more restrictive of the two KEs being linked together by the KER. More help

Sex Applicability

An indication of the the relevant sex for this KER. More help

Life Stage Applicability

An indication of the the relevant life stage(s) for this KER. More help

Key Event Relationship Description

Provides a concise overview of the information given below as well as addressing details that aren’t inherent in the description of the KEs themselves. More help

This KER deals with the evidence that binding of eh Influenza HA protein to sialic acid glycans leads to viral entry into the cell.

Evidence Collection Strategy

Include a description of the approach for identification and assembly of the evidence base for the KER. For evidence identification, include, for example, a description of the sources and dates of information consulted including expert knowledge, databases searched and associated search terms/strings. Include also a description of study screening criteria and methodology, study quality assessment considerations, the data extraction strategy and links to any repositories/databases of relevant references.Tabular summaries and links to relevant supporting documentation are encouraged, wherever possible. More help

To develop this KER, the author has reviewed the literature available for Influenza A virus receptor preferences up to December 2023 to find evidence showing:

1. Receptor essentiality for viral infection (shown through host suceptibility/ tropism)

2. Mechanisms that support viral entry, including the use of proteases

Evidence Supporting this KER

Addresses the scientific evidence supporting KERs in an AOP setting the stage for overall assessment of the AOP. More help

Multiple studies have characterized virus-receptor interactions and entry pathways:

Reference	Technique	Finding
Rogers, G., Paulson, J., Daniels, R. et al. Single amino acid substitutions in influenza haemagglutinin change receptor binding specificity. Nature 304, 76–78 (1983). https://doi.org/10.1038/304076a0	Hemagglutination assay, HAI	Specific mutations at site 226 in HA impact sialic acid linkage binding preference
Rogers GN, Pritchett TJ, Lane JL, Paulson JC. Differential sensitivity of human, avian, and equine influenza A viruses to a glycoprotein inhibitor of infection: selection of receptor specific variants. Virology. 1983 Dec;131(2):394-408. doi: 10.1016/0042-6822(83)90507-x. PMID: 6197808.	Hemagglutination assay, HAI	Human, avian, and equine H3 Influenza A viruses have different abilities to bind sialic acid (human prefer 2,6, animals prefer 2,3).
Childs, R., Palma, A., Wharton, S. et al. Receptor-binding specificity of pandemic influenza A (H1N1) 2009 virus determined by carbohydrate microarray. Nat Biotechnol 27, 797–799 (2009). https://doi.org/10.1038/nbt0909-797	Carbohydrate microarray	Pandemic viruses were able to bind both 2,6 and 2,3 linked sialyl glycans while seasonal viruses only bound 2,6
Matrosovich M, Tuzikov A, Bovin N, Gambaryan A, Klimov A, Castrucci MR, Donatelli I, Kawaoka Y. Early alterations of the receptor-binding properties of H1, H2, and H3 avian influenza virus hemagglutinins after their introduction into mammals. J Virol. 2000 Sep;74(18):8502-12. doi: 10.1128/jvi.74.18.8502-8512.2000. PMID: 10954551; PMCID: PMC116362.	Solid- phase receptor binding assay	Alteration of receptor binding efficiency may be a prerequisite for zoonosis
Crusat M, Liu J, Palma AS, Childs RA, Liu Y, Wharton SA, Lin YP, Coombs PJ, Martin SR, Matrosovich M, Chen Z, Stevens DJ, Hien VM, Thanh TT, Nhu le NT, Nguyet LA, Ha do Q, van Doorn HR, Hien TT, Conradt HS, Kiso M, Gamblin SJ, Chai W, Skehel JJ, Hay AJ, Farrar J, de Jong MD, Feizi T. Changes in the hemagglutinin of H5N1 viruses during human infection--influence on receptor binding. Virology. 2013 Dec;447(1-2):326-37. doi: 10.1016/j.virol.2013.08.010. Epub 2013 Sep 17. PMID: 24050651; PMCID: PMC3820038.	Hemagglutination assay, receptor binding assay using sialylglycopolymers, biolayer interferometry analysis, carbohydrate microarray analysis, crystallography	H5N1 infection of human leads to decreased ability to bind 2,3 linked sialic acid
Matlin, K.S., Reggio, H., Helenius, A. & Simons, K. Infectious entry pathway of influenza-virus in a canine kidney-cell line. J. Cell Biol. 91, 601–613 (1981)	Electron microscopy	Virus was seen bound to microvilli, in coated pits, coated vesicles, and large smooth-surfaced vacuoles, low pH was required for fusion, suggesting entry by endocytosis
Rust, M., Lakadamyali, M., Zhang, F. et al. Assembly of endocytic machinery around individual influenza viruses during viral entry. Nat Struct Mol Biol 11, 567–573 (2004). https://doi.org/10.1038/nsmb769	Real- time fluorescent microscopy	Clathrin-mediated and clathrin- and caveolin-independent endocytic pathways used in parallel with similar efficiency
De Vries, E. et. al., Dissection of the Influenza A Virus Endocytic Routes Reveals Macropinocytosis as an Alternative Entry Pathway. Plos Pathogens (2011). https://doi.org/10.1371/journal.ppat.1001329	Luciferase reporter assay	Macropinocytosis is an alternative entry pathway
Chen, C. and Zhuang, X. Epsin 1 is a cargo- specific adaptor for the clathrin-mediated endocytosis of the influenza virus	Colocalization of immunofluorescence	influenza entry via clathrin- mediated pathway
Sieczkarski, S. and Whittaker, G. Influenza Virus Can Enter and Infect Cells in the Absence of Clathrin-Mediated Endocytosis	Flow cytommetry	IAV cell entry via non-clathrin dependent route

Biological Plausibility

Addresses the biological rationale for a connection between KEupstream and KEdownstream. This field can also incorporate additional mechanistic details that help inform the relationship between KEs, this is useful when it is not practical/pragmatic to represent these details as separate KEs due to the difficulty or relative infrequency with which it is likely to be measured. More help

Empirical Evidence

Provides specific (citable) evidence that supports the idea of a change in the upstream KE (KEupstream) leading to, or being associated with, a subsequent change in the downstream KE (KEdownstream), assuming the perturbation of KEupstream is sufficient. More help

Uncertainties and Inconsistencies

Addresses inconsistencies or uncertainties in the relationship including the identification of experimental details that may explain apparent deviations from the expected patterns of concordance. More help

-The exact receptor used by IAV for entry remains unknown, and binding is modified by surround glycans as well

-Recent findings suggest phsophor-glycans could be a potential alternative receptor

-Two subtypes of IAV found exclusively in South and Central American bats (H17N10 and H18N11) use MHC class II for entry

Known modulating factors

This table captures specific information on the MF, its properties, how it affects the KER and respective references.1.) What is the modulating factor? Name the factor for which solid evidence exists that it influences this KER. Examples: age, sex, genotype, diet 2.) Details of this modulating factor. Specify which features of this MF are relevant for this KER. Examples: a specific age range or a specific biological age (defined by...); a specific gene mutation or variant, a specific nutrient (deficit or surplus); a sex-specific homone; a certain threshold value (e.g. serum levels of a chemical above...) 3.) Description of how this modulating factor affects this KER. Describe the provable modification of the KER (also quantitatively, if known). Examples: increase or decrease of the magnitude of effect (by a factor of...); change of the time-course of the effect (onset delay by...); alteration of the probability of the effect; increase or decrease of the sensitivity of the downstream effect (by a factor of...) 4.) Provision of supporting scientific evidence for an effect of this MF on this KER. Give a list of references. More help

Modulating Factor (MF)	MF Specification	Effect(s) on the KER	Reference(s)
Viral Origin	Viruses originating from different hosts have different preferences (ex: alpha 2,6 vs alpha 2,3 linkage preference)	changes tropism, efficiency	Rogers GN, Pritchett TJ, Lane JL, Paulson JC. Differential sensitivity of human, avian, and equine influenza A viruses to a glycoprotein inhibitor of infection: selection of receptor specific variants. Virology. 1983 Dec;131(2):394-408. doi: 10.1016/0042-6822(83)90507-x. PMID: 6197808.

Quantitative Understanding of the Linkage

Captures information that helps to define how much change in the upstream KE, and/or for how long, is needed to elicit a detectable and defined change in the downstream KE. More help

Viral infection efficiency follows a Poisson distribution (1). While the rate ans strength of attachment, and speed of entry, have been determined, the exact ratio of binding to entry remains unknown.

Response-response Relationship

Provides sources of data that define the response-response relationships between the KEs. More help

Time-scale

Information regarding the approximate time-scale of the changes in KEdownstream relative to changes in KEupstream (i.e., do effects on KEdownstream lag those on KEupstream by seconds, minutes, hours, or days?). More help

The timing from viral attachment to entry has been determined to be 10 minutes (2).

Known Feedforward/Feedback loops influencing this KER

Define whether there are known positive or negative feedback mechanisms involved and what is understood about their time-course and homeostatic limits. More help

Domain of Applicability

A free-text section of the KER description that the developers can use to explain their rationale for the taxonomic, life stage, or sex applicability structured terms. More help

References

List of the literature that was cited for this KER description. More help

1. Figliozzi RW, Chen F, Chi A, Hsia SC. Using the inverse Poisson distribution to calculate multiplicity of infection and viral replication by a high-throughput fluorescent imaging system. Virol Sin. 2016 Apr;31(2):180-3. doi: 10.1007/s12250-015-3662-8. PMID: 26826079; PMCID: PMC4851903.

2. Dou D, Hernandez-Neuta I, Wang H, Ostbye H, Qian X, Thiele S, et al. Analysis of IAV replication and co-infection dynamics by a versatile RNA viral genome labeling method. Cell Rep (2017) 20:251–63. doi:10.1016/j.celrep.2017.06.021