A dengue virus vaccine prospect, developed by The University of Queensland (UQ), has had promising results in animal model testing. It produced a protective reaction in immune dengue-infected mice.
The exciting milestone provides hope to many since 390 million people are infected every year – and it’s a notoriously challenging pathogen to deal with. The most exciting part is how the vaccine isn’t injected but applied to the skin via a high-density microarray patch (HD-MAP) – more simply put, microneedle patches.
Dengue fever is one of the tropical regions’ most prevalent diseases. Mosquitos carry the virus and infect people when they bite them. According to Jovin Choo, a UQ Ph.D. candidate who participated in the study, this research could lead to a readily administered vaccine that could halt the devastation of dengue fever worldwide. For now, efforts to tackle it mainly focus on prevention.
Preventative measures involve targeting mosquitoes with traps, making the insect resistant to the virus, genetic engineering to reduce their numbers, or exposing them to bacteria that stop the virus from growing. There is one vaccine currently available, known as Dengvaxia, but it’s not very good. It’s bedeviled with problems.
The most severe being that it could even make a subsequent infection more serious if administered to someone who has never been infected. So, only people who have been infected before can receive the vaccine. But sometimes someone could have had dengue but not know, mistaking it for some other feverish illness. The UQ team is optimistic their new vaccine will skirt these problems.
Jovin Choo, the first author of the study, stated:
Dengue is the most significant mosquito-borne viral disease in the world’s tropical zone, infecting 390 million and killing 25,000 annually, resulting in an annual estimated economic cost of $8.9 billion. While a dengue vaccine technically already exists, it’s only licensed to be used in certain countries where the Dengue virus is endemic – and with restricted use. So, to properly fight this terrible disease, we’ve engineered a vaccine candidate based on a platform technology that uses an Australian insect virus called Binjari virus.
To make the vaccine, the researchers created a chimera by merging the dengue virus with the recently discovered Binjari virus (which infects bugs and is harmless to humans), creating an artificial virus. It consists of a Binjari virus base with dengue virus proteins so the patient’s immune system can recognize it as dengue to launch a response.
This method comes with several advantages. Ms. Choo said:
For instance, the particles exactly mimic the surface of their dengue counterpart, which induces a strong, authentic, and protective immune response. Also, it allows us to very easily manufacture high yields of the vaccine candidate in mosquito cell culture. And it only grows in insect cells, and not mammalian cells, making it extremely safe.
In the experiments with mice, all groups that received the vaccine plus adjuvant were 100% protected against the dengue virus; the group without the adjuvant, 80%. Furthermore, the painless microneedle patches turned out to be more effective than a traditional hypodermic needle.
Dr. David Muller, a UQ researcher and one of the study’s senior authors, stated another advantage: the vaccine could also offer potent antibodies when delivered via the patch. He said:
Using the microarray patch, we’re able to employ needle-free delivery of the vaccine to the immune cell-rich layers of the skin with just a click. This targeted delivery allows us to achieve potent neutralizing antibody responses using a fraction of a typical dose delivered by injection. The ease of administration, coupled with lower dose amounts, means that the patch could provide both an efficient and inexpensive vaccination option.
Dr. Jody Hobson-Peters, another UQ researcher involved in the study, said this is only the beginning of much more research, and the team is looking to apply these techniques more widely. He said:
There are four variations of dengue that are closely related, all of which can cause severe disease. So we’re now expanding our ongoing pre-clinical studies to all four of these forms of dengue virus. And we’re also looking to adopt this technology to other viruses, like the Zika virus, West Nile virus, and Japanese encephalitis virus. These are daunting diseases, but cheap, easy and accessible vaccinations for them might one day be just a click away.
While the results are promising, there’s still plenty more work to do because there are four strains of dengue to tackle, and mouse studies are still a long way from human success.
