Influenza NS1 protein is the main viral protein counteracting host innate immune responses, allowing the virus to efficiently replicate in interferon (IFN)-competent systems. In this study, we analyzed NS1 protein variability within influenza A (IAV) H3N2 viruses infecting humans during the 2012-2013 season. We also evaluated the impact of the mutations on the ability of NS1 proteins to inhibit...

avian influenza (ai) is a highly contagious disease in poultry and outbreaks can have dramatic economic and health implications. for effective disease surveillance, rapid and sensitive assays are needed to detect antibodies against ai virus (aiv) proteins. in order to support eradication efforts of avian influenza (ai) infections in poultry, the implementation of “diva” vaccination strategies, ...

The non-structural protein 1 (NS1) of influenza A virus (IAV), coded by its third most diverse gene, interacts with multiple molecules within infected cells. NS1 is involved in host immune response regulation and is a potential contributor to the virus host range. Early phylogenetic analyses using 50 sequences led to the classification of NS1 gene variants into groups (alleles) A and B. We rean...

Type I interferons (IFNs) function as the first line of defense against viral infections by modulating cell growth, establishing an antiviral state and influencing the activation of various immune cells. Viruses such as influenza have developed mechanisms to evade this defense mechanism and during infection with influenza A viruses, the non-structural protein 1 (NS1) encoded by the virus genome...

Influenzavirus non-structural protein NS1 is involved in several steps of the virus replication cycle. It counteracts the interferon response, and also exhibits other activities towards viral and cellular RNAs. NS1 is known to bind non-specifically to double-stranded RNA (dsRNA) as well as to viral and cellular RNAs. We set out to search whether NS1 could preferentially bind sequence-specific R...

The NS1 protein of influenza A viruses is known as a nonessential virulence factor inhibiting type I interferon (IFN) production in mammals and in chicken cells. Whether NS1 inhibits the induction of type I IFNs in duck cells is currently unknown. In order to investigate this issue, we used reverse genetics to generate a virus expressing a truncated NS1 protein. Using the low pathogenic avian i...

The genome of influenza A virus consists of eight single-stranded RNA molecules of negative polarity. Their replication and transcription take place in the nucleus of infected cells using ribonucleoprotein complexes (RNPs) as templates. Two of the viral transcripts, those generated by RNPs 7 and 8, can be spliced and lead to two alternative protein products (M1 and M2, NS1 and NEP/NS2, respecti...

Many proteins that function in the transcription, maturation, and export of metazoan mRNAs are concentrated in nuclear speckle domains, indicating that the compartment is important for gene expression. Here, we show that the NS1 protein of influenza B virus (B/NS1) accumulates in nuclear speckles and causes rounding and morphological changes of the domains, indicating a disturbance in their nor...

The NS1 protein of influenza A viruses is the dedicated viral interferon (IFN)-antagonist. Viruses lacking NS1 protein expression cannot multiply in normal cells but are viable in cells deficient in their ability to produce or respond to IFN. Here we report an unbiased mutagenesis approach to identify positions in the influenza A NS1 protein that modulate the IFN response upon infection. A rand...

The effect of NS1 protein on the efficiency of influenza virus mRNA translation was evaluated by determining the accumulation of nucleoprotein (NP) or M1 mRNAs in the cytoplasm of cells expressing either of these genes alone or in combination with the NS1 gene, as well as the total cell accumulation of NP or M1 protein. Coexpression of NS1, but not of NS2 protein, led to increases in the transl...