快猫短视频

Sydney

TRIALS of a type of gene therapy that slices through the genetic material of
HIV and prevents it from multiplying have begun in Australia. Within a few
months they should provide the first signs of whether the technique can halt the
progression of AIDS.

Existing treatments try to reduce the amount of HIV in the body with a
cocktail of anti-viral drugs. But researchers at Gene Shears, a biotechnology
company in Sydney, will try to discover whether an immune system already under
attack can be repaired from within.

Last week, Gene Shears announced that it had begun clinical trials of an
engineered 鈥渞ibozyme鈥濃�攁 molecule of RNA that behaves like an enzyme and
cuts through a vital part of HIV鈥檚 genetic material. In laboratory tests, the
ribozyme, called Rz2, halts replication of HIV inside CD4 cells. These are the
white blood cells, or lymphocytes, that the virus commandeers at the outset of
infection, converting them into factories turning out multiple copies of the
virus.

Six pairs of identical twins are taking part in the trials at St Vincent鈥檚
Hospital, Sydney. One twin in each pair is HIV-positive, the other is negative.
The team takes healthy lymphocytes from the uninfected twin, equips them with
the gene that makes the ribozyme and injects them into the HIV-positive twin.
The gene is carried into the lymphocytes on board a disarmed mouse leukaemia
virus. This inserts the anti-HIV gene into human DNA, allowing the lymphocyte to
create its own ribozyme.

Indications of how the armed cells are faring are expected in six months.
Their survival will be the first sign that gene therapy can halt the progress of
AIDS. 鈥淚鈥檓 very optimistic about it,鈥� says David Cooper, head of the Centre for
Immunology and HIV Medicine at St Vincent鈥檚. 鈥淎t worst we expect this technology
to be complementary to existing therapies.鈥�