Viruses: More Friends Than Foes (Revised Edition). Karin Moelling
not be recognized by the vaccine. After a first shock this was not a real problem because a Phase I Clinical Trial in patients is normally only a safety test. Of course we would have liked to see some efficacy, some protection, even though that is not the purpose of such a trial. The DNA construct is now in use in the U.S. military, but in combination with other vaccines. Especially a sequential approach is attractive, “prime-boost”, in this case a DNA-prime — and virus boost. The virus is a modified Adenovirus with HIV landmarks, because virus particles lead to best immune responses. The DNA vaccine has apparently a training effect on immune cells, making them into long-lived memory cells. We observed that as an unexpected effect. The virus for the boost is sometimes constructed to contain rare triplets, designated as “codon deoptimization”; this slows down the virus production. Such attenuation, which is frequently intended for vaccines, results in the viruses being unable to cause diseases. Real but slowed-down viruses have been used as the basic principle for vaccines in the past. To administer DNA, injection-needles are no longer used; pistols are now applied to shoot the DNA into the muscles. I have such a pistol in a safety box with a red velvet lining, delivered by the producer, making it look very valuable — however, we did not find this type of injection very effective. Better pistols may have to be designed. This type of DNA vaccination is used worldwide in many variants: against influenza, respiratory-syncytial or Ebola and the newly emerging Zika viruses. Yet DNA alone is too inefficient, so combinations with other vaccines are required. In contrast to viruses, cancer cells often do not expose foreign proteins on their surface, so that one cannot train the immune system easily to recognize them as targets for antibody production. One therefore tries recently to exploit not antibody production but rather the stimulation of cell-mediated immunity, by growing lymphocytes with DNA coding for cytokines. We therefore injected such an (interleukin-12-producing) DNA into malignant melanoma patients in a clinical trial — with some effect (see below). Help for self-help is the idea.
Microbicides as “condoms” for women
Anti-HIV drugs which failed as oral therapies have recently been developed into drugs for local application in the vagina as protection against sexual transmission of HIV. Worldwide, women want to be responsible for their protection and do not wish to leave that to their male partners. It turned out that the vagina, as a target of microbicides to inactivate microbes and HIV, was surprisingly poorly characterized. Two microbicide trials by the Bill and Melinda Gates Foundation failed at late stages of development and had to be terminated prematurely, as the microbicides were found to enhance, instead of preventing, infections with HIV. In spite of its competence and reputation, the Gates Foundation failed — which must indicate that our state of knowledge is inadequate.
Together with a dozen European scientists I once organized a Global-Exchange EMBO course on HIV/AIDS in Stellenbosch, South Africa, in 2010 with support from the European Molecular Biology Organization (EMBO) and my grant. EMBO started this as one of the first steps to go global outside of Europe. South Africa is the country with the highest HIV prevalence worldwide. 60 young Africans participated, some of them hesitated to apply and did not dare to inform others about it — HIV was a stigmatized topic. The former President of South Africa, Thabo Mbeki, proclaimed for many years that HIV infections could be avoided by taking a shower. This must have killed people.
The students liked the congress bags with the EMBO logo and almost fought for them. We did not have enough, because half the bags disappeared at the customs and never showed up again. The course took place in a safe location at Stellenbosch in a building sponsored by the Swedish Wallenberg Foundation. The students barely dared to travel back and forth to and from Cape Town, and never after sunset. They were afraid to pass by the local townships.
In a township close to Cape Town a million people lived in primitive shelters built of cartons, car tires or corrugated iron. We estimated that for these many people there were about 50 dry toilets, blue cabins aligned next to each other almost outside the village. Instead of visiting the Dutch vineyards we attended a church service in a township. It was all about AIDS — the sermons, the prayers, the decorations and the discussions afterwards, people approaching us foreigners: “We need help” — men think they can get rid of HIV by having contact with a virgin — what a fatal error! On the whole, sadly, I saw little output for my investment of time and effort into the course. Bigger organizations are now increasingly successful.
All microbicide studies have so far failed. Even the results of the most promising one from South Africa, the CAPRISA-trial, which was presented during the EMBO-meeting and at an international AIDS Congress in Rome, where it caused a big splash — turned out to be not directly reproducible. Another microbicide study, PrEP-VOICE, comprising 10,000 women was no success. More than 30% did not take the drug as prescribed — lack of compliance was the explanation — which is often lack of education and perhaps their living standard, with poor housing. A dozen microbicides have failed by now. To prevent unreliable intake of pills by the volunteers, a systemic long-lasting injected medicine is an option, which is under investigation with an integrase inhibitor. Ashley Haase from the University of Minnesota, Minneapolis showed that HIV does not infect the cells lining the vagina, but that the virus bypasses them through cellular junctions. A short-cut taken by the virus — so that cellular compounds are ineffective, as the virus stays outside the cells. Our compound would fit.
Thus the trials were not designed properly because of lack of knowledge. Researchers have to get their “homework” done, was the conclusion. The virus has to be killed before entering the cells. Two clinical trials with microbicides are ongoing in 2016 ((CONRAD 128 and MTN-030/IPM 041) and a vaginal ring was tested with dual functions, against pregnancy and HIV infection with moderate results.
Driving HIV into “suicide”
Together with my colleagues we designed an approach in Zurich, to kill HIV before it infects a cell. Application in the vagina as microbicide seemed the most urgent application to us. “Driving HIV into suicide” was the headline of a commentary in the journal Nature Biotechnology where we published our results (2007). The University of Zurich printed postcards with this slogan, which one could pick up in the streetcars during the jubilee of the University. However, this did not help us to put the approach into practice. It is just too difficult and too expensive. The suicide of the virus is based on “molecular scissors” called RNase H, causing cleavage of the RNA in RNA-DNA hybrids. This process normally takes place inside cells after the viral RNA has been copied to DNA and is then useless. The scissors are present inside the virus particle, ready to go to work after the virus has entered the cell. Its activation inside the particles destroys the RNA before it is copied, so that the virus cannot replicate — a “suicide” or a dead end for the viral life cycle. (The scissors RNase H is one of four retroviral enzymes, the only one not yet targeted by an inhibitory drug because there are too many similar enzymes inside the cell. We activate this enzyme: treat the virus before it enters a cell and offer a piece of DNA which leads to a hybrid and activates the viral scissors, which kills the virus. We described the effect correctly as “silencer DNA” — but got a furious response from a reviewer, who said that only “silencer RNA” was acceptable — we gave in.)
A co-worker of mine introduced the DNA hairpin into the vagina of mice, using a gel as carrier. Only five years later we noticed that the same substance was approved by the U.S. agencies as a “wellness factor” during sexual intercourse and a lubricant for medical instruments in the trachea etc. The Bill and Melinda Gates foundation accepted our compound for testing in a standardized procedure — to make data directly comparable. Their procedure was, however, designed against HIV inside cells. This did not apply to our compound and therefore it failed, what I foresaw but could not prevent. The hairpin destroyed HIV in a special immune-deficient SCID mouse model successfully, it completely prevented infection and it also reduced significantly the size of tumors in mice. A tumor virus mouse model is a surrogate for HIV, which does not infect mice — which is a big problem for research, so for years only precious monkeys were used. New mouse models are being developed by “knocking-in” new properties. We submitted our results on tumor reduction and prevention