By Marie Ellis From medical News Today

Chikungunya is a virus transmitted to humans by infected mosquitos. Though it mainly affects people living in Africa and Asia, it has been identified in Europe and even the US recently. Though there is no cure for the virus, the first human trial of a new vaccine – published in The Lancet – appears to provide protection against it.

The chikungunya virus is transmitted to humans by infected mosquitos. Recent cases of the virus have been reported in the US.

The name “chikungunya” comes from a word in the Kimakonde language, which means “to become contorted” – referring to the hunched appearance of sufferers with joint pain. Other symptoms of the virus include muscle pain, headache, fever, nausea, fatigue and rash. It was first described during an outbreak in southern Tanzania in 1952.

“Since 2006, the virus has caused outbreaks of disease where it had never been previously reported, including Italy, France, and most recently, the USA,” says study leader Dr. Julie Ledgerwood at the National Institute of Allergy and Infectious Diseases, National Institutes of Health.

“Currently, we have no licensed vaccines or approved drugs for this debilitating infection, which causes fever and intensely painful, severe arthritis,” she adds.

She and her colleagues explain that, unlike other chikungunya virus candidates, the new vaccine uses non-infectious virus-like particles (VLP) composed of the structural proteins from the West African strain 37997, which is typically seen by the immune system.

According to the team, the nanoparticles imitate the immune effects of actual virus particles without causing infection because they do not actually contain the virus’ genetic material.

Even low doses of vaccine are effective

Fast facts about chikungunya

It shares clinical signs with dengue and can be misdiagnosed as such

With no cure for the disease, treatment focus on relieving symptoms

As of August 12, 2014, 584 cases of the virus have been reported from US states.

Previous research conducted in rhesus macaques revealed that this vaccine provided protection from infection, so the researchers conducted a phase 1 trial in 25 healthy human volunteers between the ages of 18-50 years old.

They each received an injection of one of three different doses of the vaccine at weeks 0, 4 and 20. In addition, their chikungunya neutralizing antibodies were measured regularly.

The team reports that the vaccinations were well tolerated and that there were no serious adverse events or inflammatory side effects recorded. Of the 25 participants, four reported mild to moderate side effects, which included increases in transient alanine aminotransferase – an enzyme in liver and heart cells that is elevated when they are damaged – and transient neutropenia – low white blood cell count.

In the majority of recipients, the researchers observed an immune response via neutralizing antibodies after the first vaccination, and they report that even the lowest doses of the vaccine were effective.

Additionally, after the second vaccination, all recipients from all of the dose groups had high antibody levels. These antibodies were long-lasting and could be detected in all study participants at 6 months after their last vaccination.

New vaccine could provide long-term protection

Dr. Ledgerwood says antibody levels at 11 months after vaccination were similar to those seen in people who had recovered after being infected with chikungunya, “suggesting that the VLP vaccine could provide long-term protection against the virus.”

This vaccine should be economically viable in large quantities, she says, “because it needs minimal containment as live virus is not required for production.” According to Dr. Ledgerwood, the same approach could be used in the production of vaccines against other viruses related to chikungunya.

But in a linked comment to the study, Dr. Ann Powers, from the Centers for Disease Control and Prevention (CDC), notes that getting a vector-borne virus vaccine licensed can be difficult:

“Development of vaccines for orphan agents is challenging because the market might not be large enough to justify the investment. The cost of development of a vaccine – from preclinical studies to vaccine registration – is estimated to be $200-500 million.”

Even so, she adds that such vaccines “are still the most cost-effective strategy for disease prevention,” and says that because so many chikungunya outbreaks have occurred within a matter of months, “the continued development of this VLP vaccine candidate, along with other vaccine options, should be encouraged.”

For more on this story go to: http://www.medicalnewstoday.com/articles/281062.php

Related story:

Safety and tolerability of chikungunya virus-like particle vaccine in healthy adults: a phase 1 dose-escalation trial

From The Lancet

Background

Chikungunya virus—a mosquito-borne alphavirus—is endemic in Africa and south and southeast Asia and has recently emerged in the Caribbean. No drugs or vaccines are available for treatment or prevention. We aimed to assess the safety, tolerability, and immunogenicity of a new candidate vaccine.

Methods

VRC 311 was a phase 1, dose-escalation, open-label clinical trial of a virus-like particle (VLP) chikungunya virus vaccine, VRC-CHKVLP059-00-VP, in healthy adults aged 18—50 years who were enrolled at the National Institutes of Health Clinical Center (Bethesda, MD, USA). Participants were assigned to sequential dose level groups to receive vaccinations at 10 μg, 20 μg, or 40 μg on weeks 0, 4, and 20, with follow-up for 44 weeks after enrolment. The primary endpoints were safety and tolerability of the vaccine. Secondary endpoints were chikungunya virus-specific immune responses assessed by ELISA and neutralising antibody assays. This trial is registered with ClinicalTrials.gov, NCT01489358.

Findings

25 participants were enrolled from Dec 12, 2011, to March 22, 2012, into the three dosage groups: 10 μg (n=5), 20 μg (n=10), and 40 μg (n=10). The protocol was completed by all five participants at the 10 μg dose, all ten participants at the 20 μg dose, and eight of ten participants at the 40 μg dose; non-completions were for personal circumstances unrelated to adverse events. 73 vaccinations were administered. All injections were well tolerated, with no serious adverse events reported. Neutralising antibodies were detected in all dose groups after the second vaccination (geometric mean titres of the half maximum inhibitory concentration: 2688 in the 10 μg group, 1775 in the 20 μg group, and 7246 in the 40 μg group), and a significant boost occurred after the third vaccination in all dose groups (10 μg group p=0·0197, 20 μg group p<0·0001, and 40 μg group p<0·0001). 4 weeks after the third vaccination, the geometric mean titres of the half maximum inhibitory concentration were 8745 for the 10 μg group, 4525 for the 20 μg group, and 5390 for the 40 μg group.

Interpretation

The chikungunya VLP vaccine was immunogenic, safe, and well tolerated. This study represents an important step in vaccine development to combat this rapidly emerging pathogen. Further studies should be done in a larger number of participants and in more diverse populations.

Funding

Intramural Research Program of the Vaccine Research Center, National Institute of Allergy and Infectious Diseases, and National Institutes of Health.

For more on this story go to: http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(14)61185-5/abstract

Related story:

Chikungunya death toll in the Caribbean surpasses 30

From St Lucia News online

The death toll from the mosquito borne disease, chikungunya, now stands at 32 in the Caribbean according to the European Center for Disease Control and Prevention. Chikungunya is an illness caused by a virus that spreads through mosquito bites. The most common symptoms of chikungunya are fever and joint pain. Other symptoms may include headache, muscle pain, joint swelling, or rash. Chikungunya disease rarely results in death, but the symptoms can be severe and disabling. Most people who get sick feel better within a week. In some people, the joint pain may last for months or years.

For more on this story go to: http://www.stlucianewsonline.com/chikungunya-death-toll-in-the-caribbean-surpasses-30/#sthash.zGBfaHAJ.dpuf