Synergy or interference of a H9N2 avian influenza virus with a velogenic Newcastle disease virus in chickens is dose dependent

<p>Field observations indicate that the impact of velogenic Newcastle disease virus (vNDV) is more severe in countries with concomitant circulation of low pathogenicity avian influenza virus, as is the case in the Middle East, in particular in Israel, where H9N2 and NDV are endemic. In our study, we evaluated how the exposure of chickens to an H9N2 challenge either favours or interferes with a subsequent vNDV infection and its transmission to sentinels. For this purpose, single vNDV and sequential H9/NDV challenges were performed with increasing doses of vNDV (10¹–10⁶ EID₅₀). The H9N2 challenge made birds more susceptible to the vNDV, lowering the minimum dose required to cause an infection, exacerbating the clinical outcome, while delaying the onset of the disease and time of death. Interestingly, the presence and degree of these seemingly contrasting effects were dose-dependent and not mutually exclusive.</p

Overview of RT-PCR techniques and pig sera used by 15 ESNIP3 partners for detection and preliminary subtyping of influenza A viruses in pig samples (rt = real-time; conv. = conventional; n.a. = not applicable; CA = Cotes d'Armor; Fin = Finistere; Eng = England; Calif = California; Scot = Scotland; Neth = Netherlands; It = Italy).

<p>Virus strains marked with an asterisk (*) were used to produce sera belonging to the ESNIP3 reference panel.</p>a<p>Since end 2012 (used during the third yearly period of the project).</p><p>Overview of RT-PCR techniques and pig sera used by 15 ESNIP3 partners for detection and preliminary subtyping of influenza A viruses in pig samples (rt =  real-time; conv. =  conventional; n.a. =  not applicable; CA =  Cotes d'Armor; Fin = Finistere; Eng =  England; Calif =  California; Scot =  Scotland; Neth =  Netherlands; It = Italy).</p

Number of investigated and positive herds obtained in each country by the different partners, in the three 12-month periods of the ESNIP3 program as well as in total from November 2010 to October 2013.

<p>Percentages of positive herds and total numbers of viruses that were subtyped in the context of the passive surveillance are also given. When several partners were involved in the surveillance in a country, individual numbers are indicated in grey.</p><p>Number of investigated and positive herds obtained in each country by the different partners, in the three 12-month periods of the ESNIP3 program as well as in total from November 2010 to October 2013.</p

Number of viruses identified within the different haemagglutinin and neuraminidase subtypes and lineages in 14 countries from November 2010 to October 2013.

<p>Number of viruses identified within the different haemagglutinin and neuraminidase subtypes and lineages in 14 countries from November 2010 to October 2013.</p