Most biotechnology companies will proudly tell you how much venture capital they have raised but management at Hybrid Systems will proudly tell you they have not raised any.

Chief executive Dr Kerry Fisher explained: "When we started out, we were acutely conscious of the risks inherent in the biotech world.

"Far too often, we saw too much mutual hope rather than realism. Our plan has been to do things more slowly and do them better.

"From our early days, we have had an ongoing collaboration with a big pharmaceutical company. Also, we have been hugely successful in winning competitive grants and we carry out contract research.

"As a result, we have funded ourselves to the tune of several million pounds without sacrificing any equity.

"Now we are looking for venture capital to fund clinical trials of products."

The heart of the Hybrid technology is using common but harmless viruses to kill cells in cancer tumours and the company is also developing vaccines against cancer, HIV and malaria.

Currently, the company is working with the Gates Foundation on HIV vaccines. The main virus used is adenovirus, the common cold virus.

To treat solid tumour cancers, Hybrid's aim is to introduce the virus into tumour cells, but getting it there is not easy.

The body's immune system is particularly efficient at detecting and wiping out what it sees as invaders, so if injected into the bloodstream in pure form, the virus would never reach its intended target.

The liver plays a significant part in this, a truly effective filter that harnesses what are called Kupffer cells to repel boarders.

The answer is create a Trojan horse, a stealth' virus which can travel unchallenged through the body to reach its goal. This is achieved by coating the virus in a polymer that serves a dual purpose.

First, it protects the virus from attack by the immune system. Second, the polymer is formulated to aim it at the tumour or tumours.

Once the target is reached, the virus uses the Achilles heel of a tumour to enter its cells. To establish and grow, a tumour switches off the body's local immune system.

The virus slips under the radar' unchallenged. Inside the cells, the virus recognises where it is and replicates because there is no immune system to stop it doing so. These replications kill the cancer cells by bursting, a process called lysis. Ideally, injecting the virus into a solid tumour would be preferred, but that presents two problems.

Not all solid tumours are accessible for injection and, more important, primary tumours often spread into secondaries or metastases.

These secondaries can be anywhere in the body and of varying sizes, so direct injection is not possible.

As a result, the stealth virus is especially useful with malignant cancers, where 75 per cent of patients go on to die from metastases.

This virotherapy as it is termed works particularly well in the later stages of cancer, where tumours are more aggressive.

Also, preliminary research shows that it works well on tumours resistant to standard cancer drugs.

The other distinct advantage is reduction in side-effects, a real problem with chemotherapy.

Dr Fisher said: "Overall, the side-effects of virotherapy are less than those of the drugs given to counter chemotherapy side-effects."

Formerly, the approach was to extend lifespan. Now quality of life is the key, combined with longer life.

Phase I clinical trials will begin later this year, led by Professor Len Seymour, co-founder of the company and chair of genetic therapies at Oxford University.

Hybrid Systems began life in the late 1990s at Birmingham University and was incorporated in 2001 on its relocation to Oxfordshire the same year.

The move was prompted not only by Prof Seymour's appointment, but also because of the Oxfordshire biotechnology cluster and the incubator facilities on offer.

"Having vital bits of expensive kit available but not having to buy it was a godsend," said Dr Fisher. Now based at the Heyford Innovation Centre, Upper Heyford, the company is breaking new ground in bringing immunologists and polymer chemists together.

Immunologists study the immune system's role in countering allergies or diseases while the polymer chemists research the coatings for the viruses.

Hybrid has an active collaboration and cross-training programme with polymer chemists in the Czech Republic.

With the move to acquire venture capital and begin the next phase of the company's development comes a strengthening of the management team, including the imminent appointment of a new chairman, a biotech big-hitter with a track record in growing companies.

Dr Fisher said: "We have tremendous expertise in working on blood, on cancer models and, of course, on viruses.

"We have made great progress on virus treatments, but it is still early days. What we are aiming for is virus therapy to form a pillar of treatment alongside the existing arsenal."