HIV vaccine production

Research on HIV over the past decade has led to many promising ideas for vaccines to prevent infection by the AIDS virus, but very few candidate vaccines have been tested in clinical trials. One reason for this is the technical difficulty of manufacturing vaccines based on the envelope proteins of the virus, according to Phil Berman, who led development of a major component of the only vaccine to have shown any efficacy against HIV in a clinical trial.

Berman, the Baskin Professor of Biomolecular Engineering at UC Santa Cruz, has now developed new methods for the production of HIV vaccines. His approach solves major technical problems which have bedeviled the field. Berman described the new methods, and the candidate vaccines his lab has produced.

Researcher was able to use robotics to shorten the time required to produce stable cell lines, needed to make the proteins for a vaccine, while at the same time greatly increasing how much of the protein the cell lines can produce. The improved yield makes it possible to reduce the size of the bioreactor needed to make vaccine for large clinical trials—from 200- to 10,000-liter vessels to 50- or 100-liter vessels—resulting in tremendous savings in the equipment required and cost of materials.

They were  able to create cell lines that make HIV envelope proteins with the right kind of carbohydrate components (called glycans) needed for an effective immune response. The carbohydrates attached to the protein are really important, something no one realized until recently. The conventional way of making these envelope protein vaccines incorporated the wrong kind of carbohydrates.

Cell lines derived from Chinese hamster ovary (CHO) cells are the industry standard used to produce complex recombinant proteins for therapeutic use. These cells are also useful for the production of HIV vaccines. The gene for the desired protein is transferred into CHO cells in a process called transfection, and tens of thousands of transfected cells are screened to find the few rare cells that produce large amounts of the protein. The best cell lines are grown in large batches, in a process similar to yeast fermentation for making beer, and the proteins are then isolated and purified.

Berman's lab developed a new robotic method to isolate high-producing cell lines making HIV envelope proteins. This shortened the time required to produce stable cell lines from 18 to 24 months to just 2 or 3 months, while increasing yields by a factor of 100 to 200. Those improvements are in comparison with Berman's previous experience creating the AIDSVAX vaccine, first at Genentech and then at VaxGen.

Fluorescent antibodies were used to label the HIV gp120 protein and identify high-producing cell lines. Credit: Phil Berman, UCSC. AIDSVAX was one component of an experimental vaccine regimen used in a large-scale clinical trial known as RV144, which showed 31 percent efficacy in preventing new HIV infections. The RV144 results showed that protection was correlated with antibodies to a certain segment of an HIV envelope protein called gp120.

 The original AIDSVAX vaccine had the completely wrong type of carbohydrate, and that we might improve the level of protection if we could find a way to make it with the proper type of carbohydrate. They set out to create a cell line that can produce the unusual glycans found on HIV envelope proteins rather than the complex glycans CHO cells normally produce. This was made possible by the powerful new gene editing technology known as CRISPR/Cas9.

 They used CRISPR to create a new cell line they called MGAT CHO, which produces proteins lacking complex glycans containing sialic acid and enriched for the simple "high mannose" type found on HIV envelope proteins. An unexpected benefit of this new cell line was that it enabled a simpler, less expensive process for recovering and purifying the proteins.

Carbohydrates may not be immunogenic, but HIV turns out that the most important antibodies are directed to carbohydrate. It leads to an improved version of the vaccine used in the RV144 trial. Berman's lab currently has two cell lines he said are ready to start producing vaccines on a large scale. He is now looking for partners and funding to bring them into clinical trials. Researchers have continued to use the AIDSVAX vaccine in clinical studies because it has been so hard to make new HIV vaccines.
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Antiretroviral drug not effective for viral suppression

Researchers conducted a randomized double-blind study of the effectiveness of an HIV vaccine and has found it to be ineffective in suppressing the virus. Antiretroviral therapy (ART) drugs allow people infected with the virus to live an almost normal existence.
Injecting patients first with a HIV multi-antigen and a DNA plasmid encoding human interleukin proteins and then following up with a booster containing a viral vector. The idea behind this approach is to nudge the immune system into learning how to combat the virus so that ART drugs are no longer needed.

The research team conducted a study designed to test the effectiveness of the vaccine. The study consisted of enlisting the assistance of early-stage patients with HIV infections who were already being treated with ARTs and assigning them to two groups-some of the patients got the vaccine while others got a placebo. Injections took place at 0, 4, 12, 24, 36 and 48 weeks. ART drug administration was halted for all of the volunteers starting at week 56 and lasting until week 72.

All of the volunteers were tested regularly throughout the study for viral loads, a measure of how well the body, along with ARTs and the vaccine, was working to suppress the virus. The researchers report that they found no measurable increase in effectiveness in any of the volunteers who were given the vaccine. Some of the volunteers who had received the placebo had lower than normal viral loads for a short time. This showed that if the study had not been conducted with placebos, the results would have showed that the vaccine had worked to a limited extent.
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HIV vaccine breakthrough

Vaccines work by imitating an infection and setting up a memory B-cell response in advance of an actual infection. In HIV infection, the body mounts a very strong antibody response in the first few weeks that partially works, reducing the viral load from millions to thousands. However it does not control viral replication any further or eliminate HIV infection, and eventually weakens so that the viral load increases again

An effective HIV vaccine may be a short step away, scientists have overcome a major stumbling block hindering its development. The inability to generate immune cells that stay in circulation long enough to stop the virus from spreading is a big problem in providing cure for HIV.

The problem can be solved  by unblocking a process linked to an HIV protein that was preventing the production of antibody-generating B-cells from the immune system. For a vaccine to work, its effects need to be long lasting, improving B-cell responses to an HIV vaccine is the key to HIV cure. The new method produced desired immune system responses that lasted more than a year in the laboratory experiment.

Producing vaccines that stimulate long-lasting B-cell responses against HIV is the solution to HIV treatment. B-cells need time to make highly effective neutralising antibodies, but in previous studies B-cell responses were so short lived, they disappeared before they had the time to make all the changes necessary to kill HIV.
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