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Expression of surface-bound nonstructural 1 (NS1) protein of influenza virus A H5N1 on Lactobacillus casei strain C1

Tan TS, Syed Hassan S, Yap WB

Lett Appl Microbiol, 2017 Jun;64(6):446-451.
PMID: 28370088 DOI: 10.1111/lam.12738

The study aimed to construct a recombinant Lactobacillus casei expressing the nonstructural (NS) 1 protein of influenza A virus H5N1 on its cell wall. The NS1 gene was first amplified and fused to the pSGANC332 expression plasmid. The NS1 protein expression was carried out by Lact. casei strain C1. PCR screening and DNA sequencing confirmed the presence of recombinant pSG-NS1-ANC332 plasmid in Lact. casei. The plasmid was stably maintained (98·94 ± 1·65%) by the bacterium within the first 20 generations without selective pressure. The NS1 was expressed as a 49-kDa protein in association with the anchoring peptide. The yield was 1·325 ± 0·065 μg mg(-1) of bacterial cells. Lactobacillus casei expressing the NS1 on its cell wall was red-fluorescently stained, but the staining was not observed on Lact. casei carrying the empty pSGANC332. The results implied that Lact. casei strain C1 is a promising host for the expression of surface-bound NS1 protein using the pSGANC332 expression plasmid.
SIGNIFICANCE AND IMPACT OF THE STUDY: The study has demonstrated, for the first time, the expression of nonstructural 1 (NS1) protein of influenza A virus H5N1 on the cell wall of Lactobacillus casei using the pSGANC332 expression plasmid. Display of NS1 protein on the bacterial cell wall was evident under an immunofluorescence microscopic observation. Lactobacillus casei carrying the NS1 protein could be developed into a universal oral influenza vaccine since the NS1 is highly conserved among influenza viruses.

Matched MeSH terms: Influenza Vaccines/genetics*
Fulltext Whole-Genome Phylogenetic Analysis of Influenza B/Phuket/3073/2013-Like Viruses and Unique Reassortants Detected in Malaysia between 2012 and 2014

Oong XY, Ng KT, Tan JL, Chan KG, Kamarulzaman A, Chan YF, et al.

PLoS One, 2017;12(1):e0170610.
PMID: 28129386 DOI: 10.1371/journal.pone.0170610

Reassortment of genetic segments between and within influenza B lineages (Victoria and Yamagata) has been shown to generate novel reassortants with unique genetic characteristics. Based on hemagglutinin (HA) and neuraminidase (NA) genes, recent surveillance study has identified reassortment properties in B/Phuket/3073/2013-like virus, which is currently used in the WHO-recommended influenza vaccine. To understand the potential reassortment patterns for all gene segments, four B/Phuket/3073/2013-like viruses and two unique reassortants (one each from Yamagata and Victoria) detected in Malaysia from 2012-2014 were subjected to whole-genome sequencing. Each gene was phylogenetically classified into lineages, clades and sub-clades. Three B/Phuket/3073/2013-like viruses from Yamagata lineage were found to be intra-clade reassortants, possessing PA and NA genes derived from Stockholm/12-like sub-clade, while the remaining genes from Wisconsin/01-like sub-clade (both sub-clades were within Yamagata Clade 3/Yam-3). However, the other B/Phuket/3073/2013-like virus had NS gene that derived from Stockholm/12-like sub-clade instead of Wisconsin/01-like sub-clade. One inter-clade reassortant had Yamagata Clade 2/Yam-2-derived HA and NP, and its remaining genes were Yam-3-derived. Within Victoria Clade 1/Vic-1 in Victoria lineage, one virus had intra-clade reassortment properties: HA and PB2 from Vic-1B sub-clade, MP and NS from a unique sub-clade "Vic-1C", and the remaining genes from Vic-1A sub-clade. Although random reassortment event may generate unique reassortants, detailed phylogenetic classification of gene segments showed possible genetic linkage between PA and NA genes in B/Phuket/3073/2013-like viruses, which requires further investigation. Understanding on reassortment patterns in influenza B evolution may contribute to future vaccine design.

Matched MeSH terms: Influenza Vaccines/genetics
Cytotoxicity and immunological responses following oral vaccination of nanoencapsulated avian influenza virus H5 DNA vaccine with green synthesis silver nanoparticles

Jazayeri SD, Ideris A, Zakaria Z, Shameli K, Moeini H, Omar AR

J Control Release, 2012 Jul 10;161(1):116-23.
PMID: 22549012 DOI: 10.1016/j.jconrel.2012.04.015

DNA formulations provide the basis for safe and cost effective vaccine. Low efficiency is often observed in the delivery of DNA vaccines. In order to assess a new strategy for oral DNA vaccine formulation and delivery, plasmid encoding hemagglutinin (HA) gene of avian influenza virus, A/Ck/Malaysia/5858/04 (H5N1) (pcDNA3.1/H5) was formulated using green synthesis of sliver nanoparticles (AgNP) with polyethylene glycol (PEG). AgNP were successfully synthesized uniformly dispersed with size in the range of 4 to 18 nm with an average size of 11 nm. Cytotoxicity of the prepared AgNP was investigated in vitro and in vivo using MCF-7 cells and cytokine expression, respectively. At the concentration of -5 log₁₀AgNP, no cytotoxic effects were detected in MCF-7 cells with 9.5% cell death compared to the control. One-day-old specific pathogen-free (SPF) chicks immunized once by oral gavage with 10 μl of pcDNA3.1/H5 (200 ng/ml) nanoencapsulated with 40 μl AgNP (3.7×10⁻² μg of Ag) showed no clinical manifestations. PCR successfully detect the AgNP/H5 plasmid from the duodenum of the inoculated chicken as early as 1h post-immunization. Immunization of chickens with AgNP/H5 enhanced both pro inflammatory and Th1-like expressions, although no significant differences were recorded in the chickens inoculated with AgNP, AgNP/pcDNA3.1 and the control. In addition, serum samples collected from immunized chickens with AgNP/H5 showed rapidly increasing antibody against H5 on day 14 after immunization. The highest average antibody titres were detected on day 35 post-immunization at 51.2±7.5. AgNP/H5 also elicited both CD4+ and CD8+ T cells in the immunized chickens as early as day 14 after immunization, at 7.5±2.0 and 20±1.9 percentage, respectively. Hence, single oral administrations of AgNP/H5 led to induce both the antibody and cell-mediated immune responses as well as enhanced cytokine production.

Matched MeSH terms: Influenza Vaccines/genetics
Purification and immunogenicity of hemagglutinin from highly pathogenic avian influenza virus H5N1 expressed in Nicotiana benthamiana

Pua TL, Chan XY, Loh HS, Omar AR, Yusibov V, Musiychuk K, et al.

Hum Vaccin Immunother, 2017 Feb;13(2):306-313.
PMID: 27929750 DOI: 10.1080/21645515.2017.1264783

Highly pathogenic avian influenza (HPAI) H5N1 is an ongoing global health concern due to its severe sporadic outbreaks in Asia, Africa and Europe, which poses a potential pandemic threat. The development of safe and cost-effective vaccine candidates for HPAI is considered the best strategy for managing the disease and addressing the pandemic preparedness. The most potential vaccine candidate is the antigenic determinant of influenza A virus, hemagglutinin (HA). The present research was aimed at developing optimized expression in Nicotiana benthamiana and protein purification process for HA from the Malaysian isolate of H5N1 as a vaccine antigen for HPAI H5N1. Expression of HA from the Malaysian isolate of HPAI in N. benthamiana was confirmed, and more soluble protein was expressed as truncated HA, the HA1 domain over the entire ectodomain of HA. Two different purification processes were evaluated for efficiency in terms of purity and yield. Due to the reduced yield, protein degradation and length of the 3-column purification process, the 2-column method was chosen for target purification. Purified HA1 was found immunogenic in mice inducing H5 HA-specific IgG and a hemagglutination inhibition antibody. This paper offers an alternative production system of a vaccine candidate against a locally circulating HPAI, which has a regional significance.

Matched MeSH terms: Influenza Vaccines/genetics