The matrix proteins of neurovirulent subacute sclerosing panencephalitis virus and its acute measles virus progenitor are functionally different.

Rinderpest (RP) and peste-des-petits-ruminants (PPR) are two important diseases of domestic ruminants.To improve on currently available vaccines against PPR, we have created cDNA copies of the RP virus genome in which either the fusion (F) or hemagglutinin (H) gene, or both, was replaced with the corresponding gene from PPR virus. It was necessary to develop a modified rescue system in which the T7 RNA polymerase was provided by a recombinant fowlpox virus and the entire rescue procedure took place in Vero cells before we could obtain live virus from these chimeric constructs. No virus was recovered when only one of the glycoprotein genes was changed, but a chimeric virus containing both F and H genes from PPR virus was reproducibly rescued from cDNA, indicating that a virus-specific functional interaction takes place between the F and H proteins. The rescued virus expressing the PPR glycoproteins grew more slowly in tissue culture than either parental virus and formed abnormally large syncytia. Goats infected with the chimera showed no adverse reaction, as assessed by clinical signs, temperature, leukocyte count, virus isolation, and serology, and were protected from subsequent challenge with wild-type PPR virus.

Section: Discussionmentioning

confidence: 99%

Recovery and Characterization of a Chimeric Rinderpest Virus with the Glycoproteins of Peste-des-Petits-Ruminants Virus: Homologous F and H Proteins Are Required for Virus Viability

Das

Baron

Barrett

2000

“…The matrix (M) protein plays crucial roles in the process of virus assembly via its interaction with both the RNP and the cytoplasmic tails of the glycoproteins. MV strains derived from patients with SSPE (SSPE strains) generally do not express a functional M protein, becoming defective in producing infectious virus particles, and thus spread via cell-to-cell fusion (10,(14)(15)(16)18). In addition, SSPE strains usually have a deletion or an alteration in the cytoplasmic tail of the F protein (4, 9, 31, 44).…”

mentioning

confidence: 99%

The SI Strain of Measles Virus Derived from a Patient with Subacute Sclerosing Panencephalitis Possesses Typical Genome Alterations and Unique Amino Acid Changes That Modulate Receptor Specificity and Reduce Membrane Fusion Activity

Seki

Yamada

Nakatsu

et al. 2011

“…It was reported that free N protein and NC-associated N protein showed different antigenicities toward antibodies, and this finding was explained to be the result of a conformational difference between the free N protein and NC-associated N protein (47)(48)(49). This suggests that conformational changes to N protein are required for NC formation.…”

Section: Discussionmentioning

confidence: 91%

Newly Identified Minor Phosphorylation Site Threonine-279 of Measles Virus Nucleoprotein Is a Prerequisite for Nucleocapsid Formation

Sugai¹,

Sato²,

Hagiwara³

et al. 2014

Measles virus nucleoprotein is the most abundant viral protein and tightly encapsidates viral genomic RNA to support viral transcription and replication. Major phosphorylation sites of nucleoprotein include the serine residues at locations 479 and 510. Minor phosphorylation residues have yet to be identified, and their functions are poorly understood. In our present study, we identified nine putative phosphorylation sites by mass spectrometry and demonstrated that threonine residue 279 (T279) is functionally significant. Minigenome expression assays revealed that a mutation at the T279 site caused a loss of activity. Limited proteolysis and electron microscopy suggested that a T279A mutant lacked the ability to encapsidate viral RNA but was not denatured. Furthermore, dephosphorylation of the T279 site by alkaline phosphatase treatment caused deficiencies in nucleocapsid formation. Taken together, these results indicate that phosphorylation at T279 is a prerequisite for successful nucleocapsid formation. Measles virus (MV), a member of the Morbillivirus genus in the Paramyxoviridae family, is an important human pathogen that causes disease characterized by fever, cough, coryza, conjunctivitis, and a maculopapular rash. Although the use of effective vaccines has decreased global mortality from measles, it remains a major cause of high mortality among children in developing countries (1-3). MV has a nonsegmented negativestranded RNA genome containing six structural genes encoding nucleoprotein (N), phosphoprotein (P), matrix (M) protein, fusion (F) protein, hemagglutinin (H) protein, and large (L) protein (4), and the P gene produces two accessory proteins, known as V and C (5, 6). N proteins encapsidate viral genomic RNA to support viral transcription and replication by an RNA-dependent RNA polymerase (RdRp) L protein. The P protein is a multifunctional protein (7,8) that assists with viral transcription and replication as a cofactor of the L protein (9, 10). The C and V accessory proteins suppress host immune responses (11,12). The M protein helps virus assembly, and the F and H proteins are required for membrane fusion and binding to the host cellular receptor, respectively (13).N protein is the most abundant viral protein in infected cells (14) and is mainly required for viral transcription and replication. N proteins tightly associate with the viral genome and antigenome to form an N-RNA complex with a herringbone-like structure (15,16). N proteins associate with every 6 bases of the 15,894-nucleotide viral genome and fully cover the genome RNA (17). This tight encapsidation allows the viral genome to be resistant to RNases and small interfering RNAs (18,19). Viral transcription and replication occur on the N-RNA complex in association with viral RdRp (vRdRp), composed of L and P proteins. This complex of N-RNA, P protein, and L protein is called the nucleocapsid (NC) and comprises 2,649 copies of the N protein, about 300 copies of the P protein, and about 20 to 30 copies of the L protein (20)(21)(22). Singly...