Introduction
Zika virus (ZIKV), first identified in 1947 from a rhesus monkey in
Uganda [1,
2], is a mosquito-borne virus belonging
to the genus Flavivirus. In 2015, outbreaks of ZIKV were reported in
Brazil, and infection was associated with microcephaly, central nervous
system malformations and Guillain–Barré syndrome (GBS)
[3]. On 1 February 2016, the World
Health Organization (WHO) declared ZIKV a ‘public health emergency of
international concern’. Moreover, ZIKV disease was listed as a ”Disease
X” by the WHO in the ”Research and Development (R&D) Blueprint for
Action to Prevent Epidemics” [4]. As
of July 2019, cases of ZIKV had been reported worldwide, including 87
countries and territories, according to a WHO report
[5]. To date, no accepted therapies or
vaccines are available for ZIKV, and the WHO has made ZIKV vaccine
development a top priority [6].
Substantial progress has been made on developing vaccines, which are
essential to control the spread of ZIKV. Moreover, new vaccine search
efforts are needed because of the complexity of ZIKV immunity and
pathogenesis [7-9]. Neutralizing
antibody epitopes exist on the surface of the ZIKV E protein
[10,
11], and precursor membrane (prM)
protein complexes with the E protein are usually ideal candidates for
vaccine development.
The gram-positive enhancer matrix-protein anchor (GEM-PA) is a new
bacterial surface display system
[12]. GEM is a peptidoglycan skeleton
of the cell wall obtained by the acid boiling of gram-positive bacteria
(food-grade non-gene-modified L. lactis ). PA is the C-terminal
domain of the AcmA protein (an important peptidoglycan hydrolase inL. lactis ). PA contains a lysin motif (LysM), which can
noncovalently bind to peptidoglycan, thus anchoring to the cell wall of
GEM [13]. GEM and PA are the vectors
and carrier proteins of the system, respectively. Target proteins fused
to PA can be anchored on the surface of GEM, namely GEM surface display
system. In this study, the GEM-PA display system was used to display
ZIKV prM-E glycoproteins on the GEM surface and study their
immunogenicity.