Gene delivery helped by deadly worm

09-Sep-2008 - Last updated on 10-Sep-2008 at 09:59 GMT

Gene therapy could be advanced by a worm more commonly associated with causing a deadly parasitic disease, according to researchers presenting at the British Pharmaceutical Conference (BPC).

The researchers believe that a protein secreted by the eggs of Schistosoma mansoni could act as a vector to insert genes into the target genetic material.

An effective technique for delivering genetic material would be a boon for gene therapy, which has the potential to treat a wide range of diseases.

University of Nottingham School of Pharmacy PhD student, Ishwinder Kaur, said: "The worm attracted the team's interest because to survive in their hosts, successful parasites have evolved sophisticated ways of evading and/or manipulating their host's immune response.

“Schistosomes can survive for more than a decade in their host. So, studying how the parasite interacts with its host's immune system can give us valuable clues as to how to exploit strategies honed by millions of years of evolution. It's a very exciting find, but much more research needs to be carried out to ensure that it has no unwanted effects on host cells."

The worm causes schistosomiasis, which is the second most socio-economically damaging parasitic disease according to the Carter Center.

It can survive against the host’s immune system and produces proteins capable of penetrating cells to reach the nucleus, traits that led to the researchers investigating it for gene therapy.

In particular the researchers investigated IPSE, a protein that is released in large quantities by the parasite’s eggs and penetrates the host’s cells. Once inside a cell IPSE enters the nucleus and binds to DNA.

The researchers discovered that IPSE can carry larger proteins with it into the nucleus, creating the possibility that it could be used as a vector in the delivery of genes.

Trials and tribulations

Gene therapy is frequently raised as a potential treatment for a wide range of ailments, with the past few weeks seeing research published on its use in treating blindness and hearing loss.

Treatments at an advanced stage of development, such as Introgen Therapeutics’ Advexin, are mainly delivered by adenoviral vectors but these are expensive to grow, difficult to store and are potentially immunogenic.

Despite these difficulties Advexin has completed Phase III trials but suffered a further setback when the US Food and Drug Administration (FDA) refused the biologics license application (BLA).

The refusal may be due to the Phase III trial having 123 patients, a relatively small number for a study.

Despite this the rejection is being viewed by some as a blow for all gene therapy treatments, which have struggled to improve their reputation following the death of Jesse Gelsinger in 1999 during a trial conducted by the University of Pennsylvania.