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ORIGINAL RESEARCH article

Front. Vet. Sci.

Sec. Veterinary Infectious Diseases

Volume 7 - 2020 | doi: 10.3389/fvets.2020.605704

This article is part of the Research TopicDiagnostic Procedures in Veterinary Microbiology and Infectious DiseasesView all 20 articles

New Diagnostic Assays for Differential Diagnosis Between the Two Distinct Lineages of Bovine Influenza D Viruses and Human Influenza C Viruses

Provisionally accepted
Faten  A OkdaFaten A Okda1,2*Julie  NelsonJulie Nelson3Eric  NelsonEric Nelson3Richard  WebbyRichard Webby1
  • 1St. Jude Children's Research Hospital, Memphis, United States
  • 2National Research Centre (Egypt), Cairo, Cairo, Egypt
  • 3South Dakota State University, Brookings, South Dakota, United States

The final, formatted version of the article will be published soon.

Influenza D virus (IDV), a novel orthomyxovirus, is currently emerging in cattle worldwide. It shares >50% sequence similarity with the human influenza C virus (HICV). Two clades of IDV are currently co-circulating in cattle herds in the U.S. New assays specific for each lineage are needed for accurate surveillance. Also, differential diagnosis between zoonotic human influenza C virus and the two clades of IDV are important to assess the zoonotic potential of IDV. We developed an enzyme-linked immunosorbent assay (ELISA) based on two different epitopes HEF and NP and four peptides, and fluorescent focus neutralization assay to differentiate between IDV bovine and swine clades. Calf sera were obtained, and bovine samples underwent surveillance. Our results highlight the importance of position 215 with 212 in determining the heterogeneity between the two lineages. We needed IFA and FFN for tissue culture–based analysis and a BSL2 facility for analyzing virus interactions. Unfortunately, these are not available in many veterinary centers. Hence, our second aim was to develop an iELISA using specific epitopes to detect two lineages of IDVs simultaneously. Epitope-iELISA accurately detects neutralizing and non-neutralizing antibodies against the IDV in non-BSL2 laboratories and veterinary clinics and is cost-effective and sensitive. To differentiate between IDVs and HICVs, whole antigen blocking, polypeptides, and single-peptide ELISAs were developed. A panel of ferret sera against both viruses was used. Results suggested that both IDV and ICV had a common ancestor, and IDV poses a zoonotic risk to individuals with prior or current exposure to cattle. IDV peptides IANAGVK (286–292 aa), KTDSGR (423–428 aa), and RTLTPAT (448–455 aa) could differentiate between the two viruses, whereas peptide AESSVNPGAKPQV (203–215 aa) detected the presence of IDV in human sera but could not deny that it could be ICV, because the only two conserved influenza C peptides shared 52% sequence similarity with IDV and cross-reacted with IDV. However, blocking ELISAs differentiated between the two viruses. Diagnostic tools and assays to differentiate between ICV and IDV are required for serological and epidemiological analysis to clarify the complexity and evolution and eliminate misdiagnosis between ICV and IDV in human samples.

Keywords: Influenza D viruses, influenza C viruses, differential diagnosis, peptide ELISAs, Blocking ELISA, Diagnostic assay

Received: 13 Sep 2020; Accepted: 11 Nov 2020.

Copyright: © 2020 Okda, Nelson, Nelson and Webby. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Faten A Okda, St. Jude Children's Research Hospital, Memphis, United States

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