Low quality antibody responses in critically ill patients hospitalized with pandemic influenza A(H1N1)pdm09 virus infection

Abstract

Although some adults infected with influenza 2009 A(H1N1)pdm09 viruses mounted high hemagglutination inhibition (HAI) antibody response, they still suffered from severe disease, or even death. Here, we analyzed antibody profiles in patients (n = 31, 17–65 years) admitted to intensive care units (ICUs) with lung failure and invasive mechanical ventilation use due to infection with A(H1N1)pdm09 viruses during 2009–2011. We performed a comprehensive analysis of the quality and quantity of antibody responses using HAI, virus neutralization, biolayer interferometry, enzyme-linked-lectin and enzyme-linked immunosorbent assays. At time of the ICU admission, 45% (14/31) of the patients had HAI antibody titers ≥ 80 in the first serum (S1), most (13/14) exhibited narrowly-focused HAI and/or anti-HA-head binding antibodies targeting single epitopes in or around the receptor binding site. In contrast, 42% (13/31) of the patients with HAI titers ≤ 10 in S1 had non-neutralizing anti-HA-stem antibodies against A(H1N1)pdm09 viruses. Only 19% (6/31) of the patients showed HA-specific IgG1-dominant antibody responses. Three of 5 fatal patients possessed highly focused cross-type HAI antibodies targeting the (K130 + Q223)-epitopes with extremely low avidity. Our findings suggest that narrowly-focused low-quality antibody responses targeting specific HA-epitopes may have contributed to severe infection of the lower respiratory tract.

Multi-strain modeling of influenza vaccine effectiveness in older adults and its dependence on antigenic distance

“…interferon type III) with age [42–44]. The neutralization rate of antibodies was also assumed to decrease with age [45].…”

Use of Biolayer Interferometry to Identify Dominant Binding Epitopes of Influenza Hemagglutinin Protein of A(H1N1)pdm09 in the Antibody Response to 2010–2011 Influenza Seasonal Vaccine

“…The final construct contained a signal sequence for secretion, a thrombin site at the C-terminus followed by a foldon sequence for generating functional trimers, and a His-Tag. The rHA2 was expressed in Hi5 cells and purified by standard His-Tag purification and subsequent size exclusion chromatography [ 44 ]. The HA2 is highly conserved between CA/07 and MI/45, and there are only four substitutions in the HA2 of MI/45 (I321V, E374K, S451N and E499K) compared with CA/07.…”

“…Influenza viruses were propagated in embryonated eggs or Madin-Darby canine kidney (MDCK) cells. Seven pH1N1 viruses were used in this study, including cell-propagated 6B.1 A/Michigan/45/2015 virus (MI/45), egg-propagated 6B.1 A/Michigan/45/2015, which carries egg-adapted mutation Q223R in HA (Q223R), and five previously reported RG-viruses [ 44 , 45 ]. The five RG-viruses were generated using the HA and neuraminidase (NA) genes from CA/08 and 6 internal genes from A/Puerto Rico/8/1934 (PR8); they were the viruses possessing wild-type CA/08 HA (CA/08), HA-K163Q mutation (K163Q), HA-D127T mutation to add an N-glycosylation motif at N125 (125gly), HA-D127N/N129T mutations to add an N-glycosylation motif at D127 (127gly), or HA-K130 deletion (K130∆).…”