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. 2025 Apr;31(4):876-878.
doi: 10.3201/eid3104.250007. Epub 2024 Mar 7.

Neutralizing Antibody Response to Influenza A(H5N1) Virus in Dairy Farm Workers, Michigan, USA

Min Z Levine, Feng Liu, Natasha Bagdasarian, Crystal Holiday, Stacie Jefferson, Zhu-Nan Li, Claudia Pappas, Terrence Tumpey, Timothy M Uyeki, Alexandra M Mellis, Krista Kniss, Joseph Coyle, Seth Eckel, Jeremy Kuo, Meghan Weinberg, Sarah Lyon-Callo, Lisa Mikesell, Becky Stoddard, Jennifer Morse

Neutralizing Antibody Response to Influenza A(H5N1) Virus in Dairy Farm Workers, Michigan, USA

Min Z Levine et al. Emerg Infect Dis. 2025 Apr.

Abstract

Since March 2024, highly pathogenic avian influenza A(H5N1) viruses have caused outbreaks in dairy cattle and poultry in the United States, and they continue to spill over into humans. However, data on human immune response to those viruses is limited. We report neutralizing antibody responses in 2 dairy farm worker H5N1 cases.

Keywords: Michigan; United States; Viruses; highly pathogenic influenza; influenza; influenza A(H5N1); neutralizing antibody response; respiratory infections; zoonoses.

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Figures

Figure
Figure
Results of microneutralization and HI assays to assess neutralizing antibody response to HPAI A(H5N1) virus infection in dairy farm workers, Michigan, USA. A) Case MI-A; B) case MI-B. We collected paired serum samples (S1 and S2) and tested against wild-type HPAI H5N1 clade 2.3.4.4b virus. Serum samples were tested at 1:10 predilution, and titer <10 was reported as 5. Dashed lines denote seropositive (titer >40) threshold at 40. GMT, geometric mean titer; HI, hemagglutination inhibition; HPAI, highly pathogenic avian influenza; S1, serum sample 1 (acute phase); S2, serum sample 2 (convalescent phase).
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