Use of the particle agglutination/particle agglutination inhibition test for antigenic analysis of SARS‐CoV‐2

• Published in: Influenza and other respiratory viruses Vol. 17; no. 2; pp. e13093 - n/a
• Main Authors: Kobayashi, Jun, Matsuyama, Shutoku, Shirakura, Masayuki, Arita, Tomoko, Suzuki, Yasushi, Asanuma, Hideki, Watanabe, Shinji, Hasegawa, Hideki, Nakamura, Kazuya
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.02.2023; John Wiley and Sons Inc
• Subjects: ACE2; Agglutination; Angiotensin; Angiotensin converting enzyme; Angiotensin-converting enzyme 2; Animals; Antibodies; antigenic analysis; Antigenicity; Antigens; Beads; Coronaviruses; COVID-19; Enzyme-linked immunosorbent assay; Enzymes; Erythrocytes; Guinea Pigs; Hamsters; Health aspects; Hemagglutination inhibition; Hemagglutination Inhibition Tests; Hemagglutinin Glycoproteins, Influenza Virus; Humans; Immune Sera; Infections; Influenza; Influenza viruses; Latex; Latex beads; Mutation; Original; Orthomyxoviridae; Pandemics; particle agglutination; particle agglutination inhibition; Peptidyl-dipeptidase A; Respiratory diseases; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Vaccines; Viral antibodies; Viral diseases; Viruses; particle agglutination; antigenic analysis; SARS‐CoV‐2; particle agglutination inhibition
• ISSN: 1750-2640; 1750-2659; 1750-2659
• DOI: 10.1111/irv.13093

Background The antigenicity of SARS‐CoV‐2 is a critical issue for the effectiveness of the vaccine, and thus, it should be phenotypically evaluated by serological assays as new field isolates emerge. The hemagglutination/hemagglutination inhibition (HA/HI) tests are well known as a representative method for antigenic analysis of influenza viruses, but SARS‐CoV‐2 does not agglutinate human or guinea pig red blood cells. Therefore, the antigenic analysis requires complicated cell‐based assays using special equipment such as plate reader or ELISPOT analyzer. Methods Based on the HA/HI tests for influenza viruses, we developed the particle agglutination/particle agglutination inhibition (PA/PAI) test to easily and rapidly quantify the virus and antibody using human angiotensin‐converting enzyme 2 (hACE2)‐bound latex beads. The virus titers were determined by mixing the beads and the virus from culture supernatant, settling it overnight, and then observing the sedimentation/agglutination pattern (PA test). The neutralization antibody titers were determined by mixing virus‐infected hamster antisera in addition to the beads and virus (PAI test). Results The PA titer was positively correlated with the plaque‐forming units. The PAI titer using the hamster antisera clearly revealed the antigenic difference between the omicron and previous variants. The antigenic differences were supported by the results shown in other methods. Conclusions The PAI test is an easy and rapid method to analyze the antigenicity of SARS‐CoV‐2.