Measles virus (MeV) is a non-segmented, negative-sense, single-stranded RNA virus of the genus Morbillivirus within the family Paramyxoviridae, order Mononegavirales. MeV is highly contagious, fever and malaise associated with cough, coryza and conjunctivitis may occur 9 to 19 days after measles virus infection, followed by papules that spread from behind the ear to the face, trunk and limbs. In rare cases, severe measles-associated central nervous system (CNS) complications may develop: Acute disseminated encephalomyelitis (ADEM), measles inclusion body encephalitis (MIBE) or subacute sclerosing panencephalitis (SSPE). Measles is a major global health threat to humans, causing approximately 207,500 deaths per year during 2000-2019 (Patel et al., 2020).

MeV enters cells through cell receptors (SLAM, CD46 or nectin-4), and infects cells by releasing its encapsidated negative-sensed genome. Entry is mediated by two MV envelope glycoproteins, the hemagglutinin (H) and the fusion (F) protein. The H protein mediates receptor attachment, while the F protein causes membrane fusion. The interaction between the H and F proteins is essential to initiate the cell entry process. After entering a cell, eight viral proteins are synthetized: six structural factors, which ensure viral genome replication and new particles formation (MV-N, MV-P, MV-L, MV-M and MV-H, and MV-F) and two non-structural proteins (MV-V ad MV-C) (Rota et al., 2016). Replication and virus assembly take place within the cytosol, and newly formed infectious particles bud from the plasma membrane before secondary infections. Finally, infected cells can fuse with uninfected cells to form syncytia, allowing the virus to spread from one cell to another without virus exposition outside of the infected cells.

• C protein The measles virus genome encodes the non-structural C and V proteins in addition to the structural proteins, which counteract, or hijack, cellular pathways to optimize intracellular replication. The MeV C protein is translated from a reading frame overlapping the 5′ terminus of the P open reading frame, and it can be detected both in the cytoplasm and the nucleus of infected cells.
• Fusion protein (F protein) The fusion protein is a homotrimer protein playing a principal role in membrane fusion. After synthesized at rough endoplasmic reticulum as an inactive precursor, F0, the F protein should be cleaved by furin in the trans-Golgi into active complex of disulfide-linked F1 and F2 subunits on the way of the transport to the cell surface. The fusion peptide exposed anew at the N-terminus of the F1 subunit is indispensable to exert fusion activity.
• Hemagglutinin (H protein) Measles virus hemagglutinin protein, an 80 kilodalton (kD) glycoprotein, is responsible for receptor binding and is the major target for neutralizing antibodies. The H protein usually contains five potential N-linked glycosylation sites which are clustered at amino acid positions 168, 187, 200, 215, 238. Some genotypes have an additional N-linked glycosylation site at position 416.
• Large protein (L protein) Measles virus large protein (MeV-L) contains all catalytic centers required for polymerization and viral mRNA capping and methylation, while phosphor- functions as an essential L chaperone, tethering L to the ribonucleoprotein (RNP) through direct interactions with both L and N proteins.
• Nucleoprotein (N protein) The genome is encapsidated by the measles virus nucleocapsid (MeV-N) protein and forms a nucleocapsid that exhibits helical symmetry. The amino-terminal region of the N protein (NCORE; amino acids [aa] 1 to 400) constitutes the core region of the helical nucleocapsid while the remaining carboxyl-terminal region (NTAIL; aa 401 to 525) is intrinsically disordered and located outside of the helical nucleocapsid core.

Although measles is a leading cause of death of young children in many developing countries, it is vaccine preventable. In addition to vaccination, WHO recommends that laboratory surveillance should be included in each country's measles control Program. Measles antigen can be used in serological diagnosis to identify diseases quickly and determine immune status (either following natural infection or post-vaccination), and can also be used for antibody preparation, western blot, Dot blot, and other protein-based assays. Creative Diagnostics now can provide measles virus for different applications. Welcome to contact us for more details.