Comparing the antibody responses against recombinant hemagglutinin proteins of avian influenza A (H5N1) virus expressed in insect cells and bacteria

Abstract

The hemagglutinin (HA) of influenza A virus plays an essential role in mediating the entry of the virus into host cells. Here, recombinant full-length HA5 protein from a H5N1 isolate (A/ chicken/hatay/2004(H5N1)) was expressed and purified from the baculovirus-insect cell system. As expected, full-length HA5 elicits strong neutralizing antibodies, as evaluated in microneutralization tests using HA5 pseudotyped lentiviral particles. In addition, two fragments of HA5 were expressed in bacteria and the N-terminal fragment, covering the ectodomain before the HA1/HA2 polybasic cleavage site, was found to elicit neutralizing antibodies. But the C-terminal fragment, which covers the remaining portion of the ectodomain, did not. Neutralizing titer of the anti-serum against the N-terminal fragment is only four times lower than the antiserum against the full-length HA5 protein. Using a novel membrane fusion assay, the abilities of these antibodies to block membrane fusion were found to correlate well with the neutralization activities.

Bacterial HA1 Vaccine against Pandemic H5N1 Influenza Virus: Evidence of Oligomerization, Hemagglutination, and Cross-Protective Immunity in Ferrets

“…1). Previous reports on the production of recombinant HA in mammalian cells, insect cells, or bacterial systems did not provide information on the presence and function of oligomers versus monomeric forms of HA (1,14,17,19,20,25,27). More recent publications emphasized the importance of high-MW oligomers for optimal immunogenicity of influenza virus recombinant HA proteins.…”

Preparation, characterization, and immunogenicity in mice of a recombinant influenza H5 hemagglutinin vaccine against the avian H5N1 A/Vietnam/1203/2004 influenza virus

“…Several single component influenza H5 virus vaccines have been developed using rHA proteins produced in mammalian, insect and bacterial expression systems. Early test results of these candidate vaccines in animals [27, 28] and in humans are encouraging; however, as shown by Treanor et al [29] even the highest dose (90 μg) of baculovirus expressed H5 rHA induced a putative protective antibody titer in only 52% of human subjects. Such a vaccine, although well tolerated, is sub-optimal against a pandemic because of the high dosage required and modest immunogenicity.…”

“…Such a vaccine, although well tolerated, is sub-optimal against a pandemic because of the high dosage required and modest immunogenicity. Shen et al [27] compared the neutralizing antibody response against the N-terminal rHA ectodomain portion (truncated before the HA1/HA2 polybasic cleavage site) produced in bacteria with the full-length rHA of H5N1 virus produced in insect cells. The results of this study indicate that the nonglycosylated HA produced in bacteria elicited neutralizing titers only four times lower than the glycosylated protein expressed in insect cells.…”

Oligomeric Recombinant H5 HA1 Vaccine Produced in Bacteria Protects Ferrets from Homologous and Heterologous Wild-Type H5N1 Influenza Challenge and Controls Viral Loads Better than Subunit H5N1 Vaccine by Eliciting High-Affinity Antibodies

“…Vaccines utilizing the expression of recombinant HA in insect, yeast, plant, and mammalian cells are under development and/or in clinical trials (13,23,40,47,51). The main challenge to the recombinant technology is to ensure that the HA products resemble the native virion-associated trimeric spike proteins and can elicit robust immune responses targeting protective conformational epitopes in the globular domain of HA (39,44).…”