人3型副流感病毒（HPIV3）是诱发婴幼儿急性下呼吸道疾病的主要病原之一，目前尚无预防HPIV3的有效疫苗。病毒样颗粒（VLPs）由病毒蛋白组成，在结构上模拟真病毒，不含基因组，无感染性。我们前期研究揭示HPIV3的基质蛋白M单独表达可形成VLP；病毒的NP、P和HN蛋白可被包装进M蛋白介导产生的VLP中。F和HN是HPIV3的两个包膜糖蛋白，属于病毒的核心抗原。本研究在前期对HPIV3 VLP的大量研究基础上，以M蛋白能包裹结构蛋白产生VLP为切入点，结合F和HN的免疫原性特点，初步阐明以M蛋白VLP为载体能更好地表达并展示F和HN的抗原表位。真核共表达M与F、HN蛋白，蔗糖密度梯度离心纯化M-F-HN VLP，探究此VLP在小鼠体内引发的免疫应答水平，与单独表达并纯化的F与HN蛋白的免疫效果相比较，评价VLP的免疫应答对小鼠的保护作用，以期为HPIV3的防治及疫苗研究提供新的理论依据。

Human Parainfluenza virus type 3 (HPIV3) is a respiratory virus belongs to paramyxoviridae. It is second only to RSV as the main cause of acute lower respiratory tract diseases in infants and young children, as well as Immunocompromised individuals. There is currently no effective antiviral therapy or vaccines available. Virus-like particles (VLPs) are particles, composed of repeating structural proteins array on their surfaces and in their cores, and these structures mimic those of infectious viruses, but without the incorporation of viral genome. Thus, VLPs are incapable of the multiple rounds of infection typical of an infectious virus. However, native viral antigens arrayed on VLP surface can contribute to the potent immunogenicity of virus. .According to our previous research, HPIV3 matrix protein (M) is able to produce VLPs when expressed alone in eukaryotic cells, thus it is responsible for the assembly and release of the virus. Viral proteins including nucleoprotein (NP), phosphoprotein (P) and Hemagglutinin-neuraminidase protein (HN) could be incorporated into M-induced VLPs. Fusion protein (F) and HN are two main envelope glycoproteins and belong to core antigens of the virus. Therefore, it is hypothesized that VLPs contain F and HN will induce strong HPIV3-specific immune responses which may protect against HPIV3 infection. .In this study, based on our previous work on VLP, we try to combine the ability of M protein with the immunogenicity of F and HN to explore whether M-induced VLPs could effectively incorporate and express the epitope of F and HN on their surfaces. M，F and HN were co-expressed in eukaryotic cells , and high quality of M-F-HN VLPs were obtained via sucrose density gradient centrifugation, Furthermore, the immune responses and immunity induced by the VLP will be evaluated, with the purified F and HN protein as a comparison. By clarifying these questions, we are expected to provide new theoretical basis for the therapeutic approaches and vaccine developments of HPIV3.