SUMOylation of Matrix Protein M1 and Filamentous Morphology Collectively Contribute to the Replication and Virulence of Highly Pathogenic H5N1 Avian Influenza Viruses in Mammals

Abstract

The matrix protein (M1) of influenza A virus plays an important role in replication, assembly, and budding. A previous study found that aspartic acid (D) at position 30 and alanine (A) at position 215 of M1 contribute to the high pathogenicity of H5N1 viruses in mice, and double mutations of D to asparagine (N) at position 30 (D30N) and A to threonine (T) at position 215 (A215T) in M1 dramatically attenuate H5N1 viruses in mice. However, the underlying mechanisms by which these M1 mutations attenuate the virulence of H5N1 viruses are unknown. Here, we found that the amino acid mutation A215T eliminates the SUMOylation of M1 by reducing its interaction with the host SUMO1 protein, significantly reducing the stability of M1, slowing the export of the M1-vRNP complex from the nucleus to the cytoplasm, and reducing viral replication in MDCK cells. We further found that the D30N mutation in M1 alters the shape of progeny viruses from filamentous to spherical virions. Our findings reveal an essential role for M1 215A SUMOylation and M1 30D-related filamentous morphology in the pathogenesis of avian influenza viruses, which could be targeted in novel antiviral drug designs. Importance Identification of the pathogenic mechanism of highly pathogenic avian influenza viruses in mammals is helpful to develop novel anti-influenza virus strategies. Two amino acid mutations (D30N and A215T) in M1 were found to collectively attenuate H5N1 influenza viruses in mice, but the underlying mechanism remained unknown. This study found that the A215T mutation significantly decreases the SUMOylation of M1, which in turn attenuates the replication of H5N1 virus in mammalian cells. The D30N mutation in M1 was found to change the virion shape from filamentous to spherical. These findings are important for understanding the molecular mechanism of virulence of highly pathogenic avian influenza viruses in mammals.

Genetic Analysis of a Novel H16N3 Virus Isolated from a Migratory Gull in China in 2021 and Animal Studies of Infection

“…Amino acid sequences of SINER/GLF were observed at the cleavage site in HA, which is typical of viruses with low pathogenicity in poultry. Several amino acid substitutions that contribute to increased virulence or transmissibility of avian influenza viruses were detected in the H16N3 virus, including PB1 207K, PB1 436Y, PA 515T, M1 30D, and M1 215A ( 15 , 16 ). Subsequently, Bayesian time-resolved phylogenetic trees for the ORFs of the HA and NA genes of the H16N3 viruses (including the related sequences downloaded from GISAID and GenBank) were constructed to elucidate their genesis and evolutionary timeline.…”

The SUMO-interacting motif in NS2 promotes adaptation of avian influenza virus to mammals

“…In addition, SUMO and target proteins can interact noncovalently through SIMs (51,52). Current studies have shown that multiple proteins of the IAV, including NS1, M1, NP, PB1, and PB2, can be modified by SU-MOylation (53)(54)(55)(56)(57). In this study, we found that NS2 contains a previously identified conserved SIM sequence in its C-terminal tail.…”

Avian influenza A virus H7N9 in China, a role reversal from reassortment receptor to the donator

“…K356R and S409N mutations occurred in almost all human isolates in Anhui province 27 . Mutations associated with increased virulence and polymerase activity, such as M1‐30D, M1‐215A, M1‐41A, and NS1‐42S, were found in all human isolates in Anhui 28–30 . Mutations associated with mammalian adaptation, such as PB1‐368V, PB2‐535L, and PB2‐588V, occurred in most isolates, particularly in Wave 5 31,32 .…”