Monoclonal antibody against the universal M2 epitope of influenza A virus.

M2 protein, a highly conserved protein of influenza A virus (IAV), plays an important role in virus particle uncoating, assembly, and budding. In the present study, eight monoclonal antibodies (mAbs) against the M2 protein of the H3N2 IAV strain were generated with recombinant truncated M2 protein or BSA-coupled M2 peptides as immunogens. The linear epitopes recognized by the mAbs were defined by IFA and peptide ELISA. The results showed that mAb 10F4 recognized an epitope located in the N-terminal 6-12 amino acids of the M2 peptide, and the mAbs 10D9, 1E2, 4B5, and 5G10 recognized the epitopes located in the C-terminal 62-77 amino acids of the M2 peptide. Importantly, mAb 10D9 recognized the M2 protein of H1-H13 IAV subtypes, which stained M2 protein located on the membrane of host cells and could be applied in immunoprecipitation and immunohistochemistry assays. The mAb 10D9 which recognizes the universal M2 epitope of IAVs will be a useful tool for studies on the function of IAV M2 protein and for the development of vaccines or detection methods for IAV infection.

Genetic characterization of H9N2 avian influenza virus in plateau pikas in the Qinghai Lake region of China.

Qinghai Lake is a major migratory-bird breeding site that has experienced several highly pathogenic avian influenza virus (AIV) epizootics. Plateau pikas (Ochotona curzoniae) have previously been implicated in the ecology of avian influenza virus in this region. We first isolated an H9N2 AIV (A/Pika/Menyuan/01/2008) from plateau pikas between November 2008 and October 2009. Sequence analysis showed that the A/Pika/Menyuan/01/2008 AIV was closely related to the H9N2 AIV strain (A/Turkey/Wisconsin/ 1/1966). Our findings suggested that plateau pikas may contribute to AIV epidemiology in the Qinghai Lake region.

BECN1-dependent CASP2 incomplete autophagy induction by binding to rabies virus phosphoprotein.

Autophagy is an essential component of host immunity and used by viruses for survival. However, the autophagy signaling pathways involved in virus replication are poorly documented. Here, we observed that rabies virus (RABV) infection triggered intracellular autophagosome accumulation and results in incomplete autophagy by inhibiting autophagy flux. Subsequently, we found that RABV infection induced the reduction of CASP2/caspase 2 and the activation of AMP-activated protein kinase (AMPK)-AKT-MTOR (mechanistic target of rapamycin) and AMPK-MAPK (mitogen-activated protein kinase) pathways. Further investigation revealed that BECN1/Beclin 1 binding to viral phosphoprotein (P) induced an incomplete autophagy via activating the pathways CASP2-AMPK-AKT-MTOR and CASP2-AMPK-MAPK by decreasing CASP2. Taken together, our data first reveals a crosstalk of BECN1 and CASP2-dependent autophagy pathways by RABV infection.

[Isolation and Identification of a Quail-origin H9N2 Subtype of The Influenza Virus and Its Biologic Characterization].

A quail-origin subtype of the influenza virus was isolated from a human-infecting H7N9 subtype of the avian influenza virus found in a live poultry market and was given the name A/Quail/Hangzhou/1/ 2013 (H9N2). We analyzed the whole genome of this virus and its biologic characteristics. Sequence analyses suggested that the: HA and NS genes belonged to a CK/BJ/1/94-like lineage; NA, NP, PA and PB1 genes belonged to a SH/F/98-like lineage; M and PB2 genes belonged to a G1-like lineage. Analyses of key amino acids showed that the cleavage site in HA protein was PSRSSR ↓ GL, and that the HA protein had a human receptor-binding site with Leu226. Deletion of amino acids 69 - 73 was detected in the stalk of NA protein, the M2 protein had an Asn31 mutation, and the NS1 protein had two mutations at Ser42, Ala149. The intravenous pathogenicity of this virus was 0.36. A study in chickens suggested that all inoculated birds shed the virus from the trachea and cloaca on the third day post-infection (p. i. ) until 11 days. All chickens that had direct contact shed the virus on the second day p. i. until 8 days. Results of virus reisolation suggested that lung and tracheal tissues could shed the virus in 5 days, whereas the other organs could shed the virus in 3 days. These results suggest that this virus strain is H9N2 subtype LPAIV, whose lineage is prevalent in mainland China. This research provides evidence on how to monitor and prevent the H9N2 subtype of the avian influenza virus.