Virion is the third in a triptych of orchestral pieces composed by Adrian Hull around the theme of viruses. The first, 'Static Infection', was composed in 2004 and is based upon the idea of the spread of a computer virus throughout a network. The second, 'Pathogenesis', was composed in 2006 and is based around the process of infection and the body’s immune system response to an infection. Both Static Infection and Pathogenesis were workshopped and recorded by the BBC National Orchestra of Wales. The final piece in the set, 'Virion', takes as its starting point an entire virus particle – the virion – as a metaphorical reflection upon mankind as a virus.
The pitch content chosen for the piece is selected using 0,1,4 tetrachords and 'stacked 5ths'. The architectonic harmonic structure of the piece utilises the extra-musical stimulus of the way in which a Virion is structured, and it's interaction with a 'host', in order to inform the narrative of the piece. The 'accompanying' yet intrinsic tape part utilises a range of techniques, including harmonically-derived impulse responses, to create a dialogue between the orchestra and the soundscape. The 'tape' part seeks to extend what is musically possible through the use of rapid and virtuosic playing, all recorded and sped up to complement the live acoustic sounds of the symphony orchestra.