Mouse Anti-PIV3 Fusion Glycoprotein Monoclonal antibody, clone 10-5-4

Human parainfluenza virus type 3 (HPIV-3) was isolated in 1957 from a pharyngeal swab of a 2-year-old child with acute respiratory illness, and early studies found that many of its epidemiologic and transmission characteristics were similar to those of influenza viruses; however, further virologic studies found it to be a respiratory virus quite different from influenza viruses, and it was classified in the family Paramyxoviridae. HPIV3 can cause severe lower respiratory tract disease in infants, young children, the elderly, and immunocompromised patients, and lower respiratory tract infections caused by HPIV-3 are an important cause of infant and child mortality in developing countries. This is why the World Health Organization has listed the HPIV-3 vaccine as a priority vaccine for future development.

HPIV-3 belongs to the family Paramyxoviridae, a genus of respiratory viruses, with typical structural features of paramyxoviruses and biological characteristics similar to those of paramyxoviruses. It is an enveloped, single-negative-stranded RNA virus with viral particles directly between 120 and 180 nm and a helically symmetrical nucleocapsid. The full viral genome is approximately 15,400 bp and encodes six proteins in sequence, including nucleocapsid protein (NP), phosphoprotein (P), matrix protein (M), fusion protein (F), hemagglutinin-neuraminidase (HN), and large molecular protein (L). F proteins are type I glycoproteins that promote cell fusion and hemolysis. Studies of the F protein lysis site revealed that the proportion of basic amino acid residues in the lysis site was positively correlated with the lysis capacity and virulence of the virus. F proteins are closely related to viral infections and are involved in viral adsorption to the surface of target cells and invasion of target cells, and antibodies against F proteins have a neutralizing effect on viruses, making F proteins the main target proteins for vaccine research.

F proteins are initially synthesized as the biologically inactive precursor protein F₀ and require protein hydrolysis to mature. Physiological oligomers are homotrimers, and only trimers can form a native conformation and acquire intracellular transporter capacity, so newly synthesized F trimers are formed in the endoplasmic reticulum. The F trimer is initially in a metastable pre-fused folded state, similar in shape to a lollipop, and consists of a membrane-proximal coiled-coiled pre-fused stalk and a single globular head domain. Both the stalk and head domains are formed synergistically by these three monomers, with the stalk attached to the transmembrane structural domain and the short C-terminal cytoplasmic tail. Anchoring of transmembrane structural domains in the lipid envelope increases the stability of the prefused conformation.

Figure 1. Schematic of paramyxovirus attachment and F proteins
(Source: Aggarwal M, et al. 2020)

Anti-parainfluenza virus type 3 Fusion Glycoprotein Monoclonal antibody
Anti-parainfluenza virus type 3 F Monoclonal antibody
Anti-PIV3 F Monoclonal antibody