Antibody Titer Has Positive Predictive Value for Vaccine Protection against Challenge with Natural Antigenic-Drift Variants of H5N1 High-Pathogenicity Avian Influenza Viruses from Indonesia

Abstract

Vaccines are used in integrated control strategies to protect poultry against H5N1 high-pathogenicity avian influenza (HPAI). H5N1 HPAI was first reported in Indonesia in IMPORTANCEH5N1 high-pathogenicity avian influenza (HPAI) virus has become endemic in Indonesian poultry, and such poultry are the source of virus for birds and mammals, including humans. Vaccination has become a part of the poultry control strategy, but vaccine failures have occurred in the field. This study identified possible causes of vaccine failure, which included the use of an unlicensed virus seed strain and induction of low levels of protective antibody because of an insufficient quantity of vaccine antigen. However, the most important cause of vaccine failure was the appearance of drift variant field viruses that partially or completely overcame commercial vaccine-induced immunity. Furthermore, experimental vaccines using inactivated wild-type virus or reverse genetics-generated vaccines containing the hemagglutinin and neuraminidase genes of wild-type drift variant field viruses were protective. These studies indicate the need for surveillance to identify drift variant viruses in the field and update licensed vaccines when such variants appear.

Expression of H5 hemagglutinin vaccine antigen in common duckweed (Lemna minor) protects against H5N1 high pathogenicity avian influenza virus challenge in immunized chickens

“…In Experiment 2 with heterologous challenge virus, although all the vaccinated birds elicited HI antibodies against the vaccine strain, only the groups that developed humoral immunity against the corresponding challenge virus survived, and on an individual basis, 19 of 20 chickens with HI antibodies against the heterologous challenge virus survived virulent challenge. Such group-and individual-level data supports a positive predictor value for survival if individual chickens had serum HI antibody titers against the challenge virus, as has been previously demonstrated [25]. However, at the individual level there were 13 individuals that lacked HI titers, but which survived heterologous challenge.…”

“…Previous reports indicate that HA similarity between vaccine and challenge virus is often associated with higher vaccine efficacy [5,25,[31][32][33]. In the current study, the HA amino acid similarity between PWT/06 and the Indo/03 vaccine (95.0%) was unexpectedly higher than between VN/10 and Indo/03 (93.5%) ( Table 4).…”

“…A single immunization of rLemna-HA conferred complete clinical protection against homologous H5N1 HPAI strain even at the lowest dose (0.2 g HA), and against heterologous VN/10 HPAI virus at both doses (0.9 g HA and 2.2 g HA). However, only partial clinical protection was achieved against challenge with antigenic variant PWT/06 strain, which was also shown to be poorly protected by inactivated vaccines derived from A/Turkey/Wisconsin/1968 (H5N9), A/Turkey/England/N28/1973 (H5N2), A/Chicken/Mexico/232/1994 (H5N2), A/chicken/Legok/2003 (H5N1), A/Goose/ Guangdong/1/1996 (H5N1), and A/duck/Vietnam/2004 (H5N3) [25]. By contrast, the 100% protection observed by rLemna-HA vaccine against Indo/03 and VN/10 H5N1 HPAI viruses were equivalent or superior to previous reports on protection provided by HA expressed in baculovirus-and other plant-based expression systems when challenged with HPAI viruses.…”

“…[25]. Viruses were propagated and titrated by allantoic sac inoculation of 9-day-of-age ECE by standard methods [26].…”

Effect of biosecurity measures and early detection systems, mitigation measures and surveillance strategies on the spread of HPAI and LPAI between farms

“…The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the rights of the authors. (Süss et al, 1994) Time interval (Swayne, 2006) Study population (Swayne, 2012) Not relevant outcomes Not relevant outcomes Not relevant outcomes (Swayne et al, 2015) Not relevant outcomes (Szeleczky et al, 2010) Not relevant outcomes (Szmaragd et al, 2009) Not relevant outcomes (Tabynov et al, 2014) Not relevant outcomes The present document has been produced and adopted by the bodies identified above as authors. This task has been carried out exclusively by the authors in the context of a contract between the European Food Safety Authority and the authors, awarded following a tender procedure.…”