Posts Tagged ‘microbicide’

Antibodies from plants are GOOD for you!

29 July, 2011

It gives me great pleasure to (re)trumpet the news that – at long last – a monoclonal antibody made in plants that neutralizes a wide range of HIV-1 variants, is going into Phase 1 clinical trial.

The MAb 2G12 is made in transgenic tobacco plants: these are grown in batches of 250 kg, harvested, and the MAb extracted under conditions of Good Manufacturing Practice (GMP).  Simple enough…yet it took years, a great deal of money, and significant exchanges with the regulatory authorities to get the clinical trial of plant-made pharmaceuticals approved.  From the Fraunhofer Institute news website:

Clinical tests for medicines made from genetically modified plants

Antibodies that have been produced in tobacco plants will now for the first time be tested in a clinical study. The decision was announced at a press conference in London on Tuesday July 19th 2011.

UK regulators have approved Europe’s first clinical trial of a monoclonal antibody produced from genetically modified plants. This landmark decision sets the stage for the testing, in humans, of an anti-HIV product made from genetically modified tobacco plants. It will open the door for trials of additional plant-derived medicines treating a range of diseases.

The trial will test the safety of a plant-derived antibody designed to stop the transmission of HIV between sexual partners when applied directly to the vaginal cavity. If proven safe in the 11 participants, the researchers can then go on to test the effectiveness of the product.

The clinical trial marks the culmination of the EU Framework 6 Pharma-Planta project, which was launched by a consortium of 30 academic and industrial partners in 2004 with €12 million in funding from the European Union. The primary goal was to develop an approved manufacturing process for recombinant pharmaceutical proteins made in plants and take one such product through all the development stages including the pivotal clinical trial.

This also represents a reward for years of perseverance by Professor Rainer Fischer, coordinator of the Pharma-Planta FP6 project and Director of the Fraunhofer IME.  From the press release:

Professor Julian Ma, scientific coordinator for Pharma-Planta and Professor of Molecular Immunology at St George’s, University of London, said: “This is a red letter day for the field. The approval from the MHRA for us to proceed with human trials is an acknowledgement that monoclonal antibodies can be made in plants to the same quality as those made using existing conventional production systems. Many people did not ever believe that it could be achieved.”

Amen to that, brother Julian…!  Readers of this blog will know we are big fans of farmed pharmaceuticals – and this is another big step along that road.

Prune(lla) juice shall set you free

25 May, 2011

I couldn’t resist that title, even though it has a qualifier for the sake of correctness: it stems from South African graffiti from the 1970s or so (collected into a book by Arnold Benjamin), and I was irresistibly reminded of it by a paper recently published in Virology Journal.  Of course, it is a pity that Prunella vulgaris is in fact a mint, and not a stone fruit, but there you go.  Yet more evidence that herbal extracts can act against viruses – and in this case, against one that really, really does does need some antagonists.

Inhibition of HIV-1 infection by aqueous extracts of Prunella vulgaris L.

ChoonSeok Oh, Jason Price, Melinda A Brindley, Mark P Widrlechner, Luping Qu, Joe-Ann McCoy, Patricia Murphy, Cathy Hauck and Wendy Maury*

Virology Journal 2011, 8:188 doi:10.1186/1743-422X-8-188  Published: 23 April 2011

Background

The mint family (Lamiaceae) produces a wide variety of constituents with medicinal properties. Several family members have been reported to have antiviral activity, including lemon balm (Melissa officinalis L.), sage (Salvia spp.), peppermint (Mentha × piperita L.), hyssop (Hyssopus officinalis L.), basil (Ocimum spp.) and self-heal (Prunella vulgaris L.). To further characterize the anti-lentiviral activities of Prunella vulgaris, water and ethanol extracts were tested for their ability to inhibit HIV-1 infection.

Results

Aqueous extracts contained more anti-viral activity than did ethanol extracts, displaying potent antiviral activity against HIV-1 at sub μg/mL concentrations with little to no cellular cytotoxicity at concentrations more than 100-fold higher. Time-of-addition studies demonstrated that aqueous extracts were effective when added during the first five hours following initiation of infection, suggesting that the botanical constituents were targeting entry events. Further analysis revealed that extracts inhibited both virus/cell interactions and post-binding events. While only 40% inhibition was maximally achieved in our virus/cell interaction studies, extract effectively blocked post-binding events at concentrations similar to those that blocked infection, suggesting that it was targeting of these latter steps that was most important for mediating inhibition of virus infectivity.

Conclusions

We demonstrate that aqueous P. vulgaris extracts inhibited HIV-1 infectivity. Our studies suggest that inhibition occurs primarily by interference of early, post-virion binding events. The ability of aqueous extracts to inhibit early events within the HIV life cycle suggests that these extracts, or purified constituents responsible for the antiviral activity, are promising microbicides and/or antivirals against HIV-1 [my emphasis].

Vaginal gel works against HIV

20 July, 2010

In a major press release at the International Aids Conference in Vienna today, published simultaneously in Science, South African researchers claimed a significant advance in prevention of HIV infection using a microbicide.

From the Commentary in Science Express by Jon Cohen:

HIV and its life cycle

For the first time ever, a vaginal gel has unequivocally blocked the transmission of HIV.
In a trial that involved nearly 900 South African women, those who received a vaginal gel that contains an anti-HIV drug had a 39% lower chance of becoming infected by the virus than those who received a placebo. …
More than 30 randomized controlled studies of microbicides, vaccines, and drugs to date have failed to thwart sexual transmission of HIV or have yielded such marginal success that researchers wound up hotly debating the data for years after the trials were complete. But there’s no ambiguity about the data from this new microbicide study reported today online in Science and in a presentation at the 18th International AIDS Conference in Vienna: Of the 444 women who received a placebo gel, 60 became infected with HIV versus 38 infections in the 445 women who received the microbicide. The result was statistically significant, and no serious side effects occurred.  “It’s a moment we’ve been waiting for 2 decades,” says epidemiologist Quarraisha Abdool Karim, who, with her husband, Salim Abdool Karim, headed the study, known as CAPRISA 004.

Published online 19 July 2009; 10.1126/science.329.5990.374

This truly is good news – both for the HIV/AIDS research and treatment community, who have needed a shot in the arm recently, and for women in developing countries who often have little choice in how or when they have sex.

From the paper in Science:

Effectiveness and Safety of Tenofovir Gel, an Antiretroviral Microbicide, for the Prevention of HIV Infection in Women

Quarraisha Abdool Karim et al., Published Online July 19, 2010
Science DOI: 10.1126/science.1193748

The CAPRISA 004 trial assessed effectiveness and safety of a 1% vaginal gel formulation of tenofovir, a nucleotide reverse transcriptase inhibitor, for the prevention of HIV acquisition in women. A double-blind, randomized controlled trial was conducted comparing tenofovir gel (n = 445) with placebo gel (n = 444) in sexually active, HIV-uninfected 18- to 40-year-old women in urban and rural KwaZulu-Natal, South Africa. HIV serostatus, safety, sexual behavior, and gel and condom use were assessed at monthly follow-up visits for 30 months. HIV incidence in the tenofovir gel arm was 5.6 per 100 women-years, i.e., person time of study observation (38/680.6 women-years), compared to 9.1 per 100 women-years (60/660.7 women-years) in the placebo gel arm (incidence rate ratio = 0.61; P = 0.017). In high adherers (gel adherence >80%), HIV incidence was 54% lower (P = 0.025) in the tenofovir gel arm. In intermediate adherers (gel adherence 50 to 80%) and low adherers (gel adherence <50%), the HIV incidence reduction was 38% and 28%, respectively. Tenofovir gel reduced HIV acquisition by an estimated 39% overall and by 54% in women with high gel adherence. No increase in the overall adverse event rates was observed. There were no changes in viral load and no tenofovir resistance in HIV seroconverters. Tenofovir gel could potentially fill an important HIV prevention gap, especially for women unable to successfully negotiate mutual monogamy or condom use.

Note my bolding above: while the results were encouraging overall, they were especially good where adherence to the protocol was high.  Moreover, it appears as though tenofovir administered externally does not get into the blood in sufficient amounts to cause infecting virus to develop resistance to any noticeable degree.  As an added bonus, the treatment appeared to reduce the incidence of herpevirus as well.

To paraphrase someone far more famous, this is only the end of the beginning of the fight against HIV and AIDS: this is not the answer; it is merely an indication that this is a strategy that may work – in the absence of a vaccine – to protect people from infection.

But so nice that it came from South Africa….


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