Ndlovu Buyani, van Zyl Albertha R, Verwoerd Dirk, Rybicki Edward P, Hitzeroth Inga I
Biopharming Research Unit, Department of Molecular and Cell Biology, University of Cape Town, Rondebosch, Cape Town 7701, South Africa.
Centre for Bioprocess Engineering Research, Department of Chemical Engineering, University of Cape Town, Rondebosch, Cape Town 7701, South Africa.
Vaccines (Basel). 2025 Jul 17;13(7):762. doi: 10.3390/vaccines13070762.
BACKGROUND/OBJECTIVES: Beak and feather disease virus (BFDV) is the causative agent of psittacine beak and feather disease (PBFD), affecting psittacine birds. There is currently no commercial vaccine or treatment for this disease. This study developed a novel BFDV coat protein mRNA vaccine encapsidated by TMV coat protein to form pseudovirions (PsVs) and tested its immunogenicity alongside BFDV coat protein (CP) subunit and DNA vaccine candidates.
mRNA and BFDV CP subunit vaccine candidates were produced in and subsequently purified using PEG precipitation and gradient ultracentrifugation, respectively. The DNA vaccine candidate was produced in cells harbouring a plasmid with a BFDV1.1mer pseudogenome. Immunogenicity of the vaccine candidates was evaluated in African grey parrot chicks.
Successful purification of TMV PsVs harbouring the mRNA vaccine, and of the BFDV-CP subunit vaccine, was confirmed by SDS-PAGE and western blot analysis. TEM analyses confirmed formation of TMV PsVs, while RT-PCR and RT-qPCR cDNA amplification confirmed encapsidation of the mRNA vaccine candidate within TMV particles. Restriction digests verified presence of the BFDV1.1mer genome in the plasmid. Four groups of 5 ten-week-old African grey parrot () chicks were vaccinated and received two boost vaccinations 2 weeks apart. Blood samples were collected from all four groups on day 14, 28 and 42, and sera were analysed using indirect ELISA, which showed that all vaccine candidates successfully elicited specific anti-BFDV-CP immune responses. The subunit vaccine candidate showed the strongest immune response, indicated by higher binding titres (>6400), followed by the mRNA and DNA vaccine candidates.
The candidate vaccines present an important milestone in the search for a protective vaccine against PBFD, and their inexpensive manufacture could considerably aid commercial vaccine development.
背景/目的：喙羽病病毒（BFDV）是鹦鹉喙羽病（PBFD）的病原体，可感染鹦鹉科鸟类。目前尚无针对该疾病的商业疫苗或治疗方法。本研究开发了一种由烟草花叶病毒（TMV）外壳蛋白包裹的新型BFDV外壳蛋白mRNA疫苗，以形成假病毒颗粒（PsVs），并将其与BFDV外壳蛋白（CP）亚单位和DNA候选疫苗一起测试其免疫原性。
mRNA和BFDV CP亚单位候选疫苗分别在[具体细胞类型]中生产，随后分别使用聚乙二醇沉淀和梯度超速离心进行纯化。DNA候选疫苗在携带含有BFDV1.1mer假基因组质粒的[具体细胞类型]细胞中生产。在非洲灰鹦鹉雏鸟中评估候选疫苗的免疫原性。
通过SDS-PAGE和蛋白质印迹分析证实了携带mRNA疫苗的TMV PsVs以及BFDV-CP亚单位疫苗的成功纯化。透射电子显微镜（TEM）分析证实了TMV PsVs的形成，而逆转录聚合酶链反应（RT-PCR）和逆转录定量聚合酶链反应（RT-qPCR）cDNA扩增证实了mRNA候选疫苗在TMV颗粒内的包裹。限制性酶切验证了质粒中BFDV1.1mer基因组的存在。将四组每组5只十周龄的非洲灰鹦鹉（[具体品种]）雏鸟进行疫苗接种，并在相隔2周的时间接受两次加强接种。在第14、28和42天从所有四组采集血样，并使用间接酶联免疫吸附测定（ELISA）分析血清，结果表明所有候选疫苗均成功引发了特异性抗BFDV-CP免疫反应。亚单位候选疫苗显示出最强的免疫反应，结合滴度较高（>6400），其次是mRNA和DNA候选疫苗。
候选疫苗是寻找针对PBFD的保护性疫苗过程中的一个重要里程碑，其低成本生产可极大地助力商业疫苗开发。
