In a fifth round of institutional funding, tuberculosis diagnostics specialist Oxford Immunotec has raised US$28 million from investors led by AIM-quoted Imperial Innovations Group.

Invesco Perpetual also joined the round, together with existing investors in the company, which was spun out of the University of Oxford in 2002.

Prior to this latest fundraising, Oxford Immunotec had raised US$82 million across four rounds of institutional investment.

The company will use the funds to develop its logistics, sales and delivery infrastructure in the US, one of its major markets. Last year it built a new lab facility in Memphis.

Oxford Immunotec’s flagship product is an immunological blood test to detect latent tuberculosis (TB) infection. In the US, certain professions undergo mandatory TB screenings annually, as do patients with HIV or rheumatoid arthritis.

Peter Wrighton-Smith, the company’s chief executive, says the funding had exceeded Oxford Immunotec’s goals.

He adds, ‘This funding will help us to expand sales and marketing at a faster rate, to penetrate new geographies and to accelerate the development and commercialisation of other assays for our expanding customer base.’

Imperial Innovations and Invesco Perpetual each contributed US$9.5 million to the round. The balance of US$9 million came from existing investors including Clarus, New Leaf, DFJ Esprit, Wellington Partners, Kaiser Permanente Ventures, SPARK Ventures and the University of Oxford.

Following the investment, Imperial Innovations holds a stake of 7 per cent in Oxford Immunotec.

As part of the deal, Nigel Pitchford, managing director of healthcare investments at Imperial Innovations, will rejoin the board of Oxford Immunotec, having previously served there from 2010 to 2011.

Imperial Innovations raised £140 million in January 2011 and invested £35.1 million in the year to July 2011, supporting 23 ventures and launching six new companies.