Fascinating
new pictures show, for the first time ever, HIV at work inside a human cell.
The pictures, from the University of Illinois, offer proof that the virus can cleverly use a cell's own machinery to drag itself inside the cell.
Scientists are fully aware how HIV causes damage once inside the cell - but little had previously been understood about how the virus actually gets in.
The Illinois study revealed how HIV can "hitch a ride" aboard a protein called dynein as it makes its way up tiny microtubules into the cell itself.
These tubules lead all the way to the cell's nucleus, where the virus can begin replicating by harnessing the cell's own ability to copy its genetic code.
The virus particles are only about 12 millionths of a centimetre in diameter - yet the University of Illinois team still managed to produce pictures of them heading for the nucleus.
They did this by attaching green fluorescent proteins from jellyfish to them, then shining a blue light on them to make them glow.
Each HIV particle then appears as a green dot on the background of the red tubules, which had also been marked with another fluorescent protein.
Photographs were taken under the microscope every 15 seconds - and revealed the virus' steady progress towards the centre of the cell.
"They don't just make a beeline for the nucleus," explained Professor David McDonald. "Their progress is somewhat halting. They appear to jump from one microtubule to another, moving in a jagged path, even sometimes moving backward, but they eventually reach their destination," he continued.
"We hope this basic research will one day lead to new targets for drug therapy in the longstanding battle against Aids."
Can milk proteins stop HIV?Various studies have shown that lactoferrin - a protein found naturally in milk and saliva - can possibly prevent viruses, such as HIV and hepatitis, from binding to healthy cells. In another study, from the Chinese University of Hong Kong, lactoferrin has been shown to strongly inhibit the reverse transcriptase enzyme, which is crucial to the HIV life cycle. Positive Nation has 12 samples of Immunecare lactoferrin tablets for the first dozen readers who write in with their name and address to: Lactoferrin offer, Positive Nation, 250 Kennington Lane, London SE11 5RD. Or email: jclarkson@positivenation.co.uk |
Drug company Roche Products announced on 15 January that it had received a European licence to market its new hepatitis C treatment, Pegasys (pegylated interferon), in combination with the antiviral drug ribavirin.
This is a particularly significant step forward in hep C treatment for people who also have HIV. Co-infection with HIV accelerates hepatitis C-related liver damage by a factor of two to three, leading to liver failure in 10-12 years on average rather than 30. Hep C liver damage also makes HIV treatment less easy to tolerate, and in some clinics the most frequent cause of HIV-related deaths is now liver failure in co-infected patients.
But one of these centres, the Boston Medical Centre in the USA, has found that only one in 10 of its HIV/hep C co-infected patients actually gets interferon/ribavirin (IFN/RBV) treatment.
Dr Catherine A Fleming found that of 149 HIV/hep C patients evaluated, only 44 (30 per cent) were deemed 'eligible' for IFN/RBV, and of these only 16 (36 per cent, or 10.8 per cent of the total) actually started it.
It doesn't stop there: current success rates for IFN/RBV - meaning that the hepatitis C virus is eliminated from the body - currently runs at up to 50 per cent for patients with the milder genotype 2 or 3 varieties of the virus, but only half that for genotypes 1 and 4. Genotype 1 is the most common, so if you have it and HIV, in Boston at least there may only be a three per cent chance you will be cured by current medication.
Dr Fleming commented: "This population of co-infected patients have many other medical and social issues that preclude them from interferon therapy." She urged that co-infected patients be assessed and supported by multidisciplinary teams earlier in the course of their illness.
Reasons given for regarding patients as unsuitable included missing appointments (23 per cent), active mental illness (21 per cent), current drug or alcohol use (23 per cent), liver disease that was too far advanced (12 per cent) and Aids (13 per cent). IFN treatment involves taking twice-weekly injections for up to a year and has difficult-to-tolerate side effects such as flu-like illness and severe depression.
Nonetheless, for the lucky few who benefit from it, IFN/RBV treatment offers a goal that has so far eluded HIV treatment - a cure.
Gus Cairns
The
first ever scientifically proven case of sexual transmission of HIV between women
has been reported in this month's edition of Clinical Infectious Diseases journal.
A 20-year-old woman from Philadelphia, USA had an HIV positive female partner. She had had a negative HIV test result six months before her positive test and had been in a monogamous relationship for two years.
She had never injected any drugs, received any blood products and did not have any piercings or tattoos - ruling those out as a means of transmission.
Furthermore, she did not have any ulcers or cuts in her mouth - thus ruling out oral transmission as well.
Doctors suspected that the woman may have been infected through sharing sex toys, noting that the toys had occasionally been used forcefully enough to draw blood.
Her bisexual HIV-positive partner carried a virus that was multi-drug resistant, showing mutations to AZT, d4T, nelfinavir, abacavir, and most other non-nucleoside and nucleoside anti-HIV drugs.
Upon investigation, it became clear that the newly-diagnosed woman carried HIV with an almost identical pattern of drug resistance.
"This is the first reported case of female-to-female sexual transmission of HIV that is supported by identification of similar HIV genotypes in the source patient and the recipient," the investigators noted.
The report includes a reminder advising lesbians in HIV-discordant relationships to practice safer sex, but notes that reports of lesbian transmission of HIV are rare.
Laurence Gibson
