The Northeast experienced an unusually warm and dry winter this year. This irregularly tepid season, quickly becoming the new norm due to climate change, is now giving way to spring rains. While the reprieve from bundling up and shoveling snow may have felt like a welcome relief, and the recent precipitation seems fortunate given the drought conditions had been plaguing the region, the past months have been especially good for insects and arachnids. Mosquitoes and ticks in particular are likely to thrive this coming summer due to these mild and wet conditions and their increased presence raises the prospect of health risks from the diseases they carry.
Zika virus and Lyme disease, transmitted by mosquitoes and ticks respectively, are two contagions that continue to cause great concern across the country. Zika virus is expected to appear once again in the southern United States this summer and continued anxiety remains about its ability to spread further north. In Connecticut, tick populations have already soared this year and testing has shown increased levels of Lyme disease bacteria. Developing vaccines to combat the rise and persistence of these diseases is the focus of Paulo Verardi’s current research. Verardi, an associate professor in the Department of Pathobiology and Veterinary Science, recently designed a quicker and safer method of producing vaccines, which has been speeding up the fight against Zika virus and Lyme disease. He is also lending his expertise to battle cancer by exploring the use of vaccines to create innovative therapies in partnership with UConn Health. While Verardi’s lab is busy with many projects, Zika virus continues to be the primary focus.
Verardi’s home country of Brazil was one of several countries in the Americas battling the disease in the recent outbreak of Zika virus, which began in early 2015. The suddenness and severity of the outbreak caused Verardi to prioritize Zika virus research.
“The media in the United States were not paying attention to Zika virus at first and then after a few months it came to dominate the news,” says Verardi, who first learned about the spread of the disease through Brazilian newspapers he reads during his daily lunch break. “Once the connection between Zika virus infection and microcephaly, which is quite rare, was established it became even more important to focus on vaccine development.”
Zika virus is transmitted by infected Aedes mosquitoes, a genus found across the globe. Though the symptoms of Zika are mostly mild, including headaches, rashes, joint and muscle pain, it can cause neurological damage and is serious for pregnant women who contract the disease. Zika virus can be passed to the fetus where microcephaly, a birth defect affecting brain development and typically resulting in permanent disability, can occur. According to the CDC, one in ten pregnant women in the United States with confirmed Zika virus infections had a fetus or baby born with birth defects. Zika virus can also be transmitted sexually and through blood transfusions. Cases of Zika virus in the United States were largely the result of mosquito bites during foreign travel.
Zika virus transmission from infected mosquitoes to humans in the United States has occurred in about 200 cases, all in Florida and Texas, but the threat from the virus remains, with no vaccine currently available and no clear answer on whether immunity develops after contracting the virus. It was recently found that traces of Zika virus remain in tissues of rhesus monkeys after it clears the blood stream. The Zika virus has surfaced around the world, first identified in 1947 in Uganda, but the effects of the surprise outbreak in the Americas demonstrate the serious threat the disease presents to cognitive development and reproductive health.
“We still don’t know a lot about Zika virus and we also don’t know how it may interact with other diseases or infections. I’m thinking of dengue virus, which is closely related to Zika virus and prevalent around the world. There are a number of diseases that may have already affected certain populations and we need to keep that in mind in developing vaccines as those other infections might present unforeseen issues,” says Verardi.
Verardi was one of the first researchers to obtain a grant toward the creation of a Zika virus vaccine. The award of $410,000 from the National Institutes of Health (NIH) in August 2016 helped propel Verardi’s work, which had started the previous year. While the World Health Organization (WHO) declared Zika a Public Health Emergency of International Concern on February 1, 2016, federal funding to combat the disease was delayed due to a showdown in Congress over budget issues. Over summer 2016, the NIH re-appropriated its funds to start research, Verardi being one of the few recipients. Professor Joan Smyth, also of the Department of Pathobiology and Veterinary Science, is a co-investigator.
Although the emergency order was rescinded by the WHO on November 18, 2016, there is still concern about the possibility of additional outbreaks, the spread of the disease to other parts of the world and the lack of a vaccine. Verardi is also concerned about the potential for future outbreaks of Zika virus and other diseases that mosquitos may carry, such as dengue, yellow fever and chikungunya. “A lot depends on the climate, especially how much rain falls,” says Verardi. There are vaccines currently available for dengue and yellow fever.
As outbreaks of mosquito-borne illness increase in number and extent, so too does disease transmission by ticks. The Northeast, mid-Atlantic and northern Midwest United States commonly see Lyme disease infections with sporadic cases throughout the rest of the country.
Ticks have a two-year life cycle and often contract the disease in their larva or nymph stages, when they feed on infected small animals such as mice and birds. As adults, ticks can remain active through the winter months, emerging to feed on warmer days.
Verardi is in the early stages of developing a vaccine to be administered to the animals that ticks feed on. “The idea is to disrupt the transmission cycle of the disease,” says Verardi. “If we can control Lyme disease in wildlife, we can limit its effects on humans and other animals. We’re just getting started on this path with the help of the Institute of Biological Risk at UConn. We are also planning to develop a version of this vaccine that targets both Lyme disease and the emerging Powassan virus.”
Developing and testing a vaccine is a lengthy process. Verardi has been working to expedite methods of developing vaccines while simultaneously increasing their safety and efficacy. He received an NIH grant of $413,000 in December 2016 for the rapid development of vaccinia virus (VACV) vectors for use as vaccines, immunotherapies and oncolytic virotherapies. Professor Joan Smyth is also a co-investigator on the grant.
VACV is used as a live vaccine, stimulating the immune system to produce antibodies against the virus and other antigens expressed by the virus. This type of vaccine is effective but presents challenges to those with weakened immune systems, such as those undergoing chemotherapy treatments, so Verardi is researching ways to increase safety for those who experience adverse reactions. Verardi uses VACV as a vaccine vector based on its success as a smallpox vaccine. The WHO certified the global eradication of smallpox in 1980.
“It’s relatively easy to express foreign genes in VACV, so we’re testing a number of potential candidates that induce good antibody and cell-mediated responses, which are two types of immune responses you want to protect against viral infections. We’re testing vaccines in small animal models right now,” Verardi says.
While Verardi established an expedited system of vaccine development, and is continuing to improve methods, it is only one step in the process of bringing a vaccine to market. The next two stages are animal testing, usually mice and then primates, and the human trials.
“We can come up with vaccine candidates relatively quickly and easily, but the testing phase is where things take time and become rather expensive. There are three phases for human trials. In phase one, you test the safety of the vaccine. In phase two, you examine how effectively the vaccine is eliciting an immune response. For phase three, you want to test how well the vaccine protects. You obviously don’t want to directly give someone the disease so you test in an outbreak area. You have to give the vaccine to a large number of people not previously exposed and have a placebo group, then wait to see the new infection rates,” Verardi says.
“One of the things we want to eventually do is to plan ahead and start developing vaccines candidates so if a disease does become a problem, we can move faster to human clinical trials. Obviously it’s hard to develop vaccines for every single agent out there, but the reality is that other exotic or barely-known viruses could start circulating at any time. Zika was a wake-up call.”
Even the arrival of a Zika vaccine, or any vaccine, might not signal the end of the development. “There is always a process of improving vaccines. There may be better antigens and vectors for it. The first generation vaccines might be expensive and cheaper options might appear but perhaps not be as efficacious. Once vaccines start to become available then the market tends to take over,” Verardi says.
Verardi has partnered with local companies, such as CaroGen Corporation in Farmington to assist on the creation of vaccines, including his Zika virus research. He has also worked with Protein Sciences Corporation in Meriden.
For a project related to his work in vaccine development, Verardi is currently collaborating with Dr. Pramod Srivastava at UConn Health to develop personalized cancer treatments, using viral vectors for immunotherapy and oncolytic virotherapy. Immunotherapies employ viruses to deliver antigens directly into the body. Oncolytic virotherapies utilize viruses to target and break down cancerous cells.
“We’re in the initial stages but we’re very excited about the prospects,” says Verardi.
Verardi has also been working with others around the globe as well, particularly in regards to Zika virus.
“The response to Zika virus was international, and sharing information and resources is crucial to developing a safe and effective vaccine,” says Verardi. “Knowing gene sequences, securing Zika virus strains, conducting experiments together and sharing advice are all critical to success.”
While vaccines can protect and lessen the devastating effects of infectious diseases, their development and administration to populations takes cooperation and international collaboration along with funding to invest in research and mitigation efforts. Risks to exposure can be lessened by awareness and preventative measures. However, infectious agents will continue to arise.