Archive for July, 2012

Building a better Rift Valley Fever vaccine

Thursday, July 19th, 2012 (last updated)

University of Texas Medical Branch researchers have significantly improved an existing experimental vaccine for Rift Valley fever virus, making possible the development of a more effective defense against the dangerous mosquito-borne pathogen.

The African virus causes fever in humans, inflicting liver damage, blindness, encephalitis and even death on a small percentage of those it infects. It also attacks cattle, sheep and goats, producing high mortality rates in newborn animals and causing spontaneous abortions in nearly all infected pregnant sheep.

In 2000, outbreaks of Rift Valley fever in Yemen and Saudi Arabia showed that the virus could expand beyond its original range. With this and the rapid North American spread of West Nile virus in mind, infectious-disease experts have long feared that Rift Valley fever virus might come to the United States or Europe, causing major human suffering and devastating the livestock industry in affected areas.

“If Rift Valley fever virus were introduced to the U.S. or Europe, it would be a very scary situation,” said UTMB assistant professor and Sealy Center for Vaccine Development member Tetsuro Ikegami, lead author of a paper on the vaccine work now online in the Journal of Virology. “To be ready to respond, we want a vaccine that can raise immune response very quickly in large animals and health workers. We also want a vaccine that will allow us to differentiate between infected and vaccinated animals.”

Ikegami’s first requirement — quick response — dictated the use of a so-called “live attenuated vaccine.” A live attenuated vaccine is a strain of virus that has been weakened to harmlessness, but still has the ability to reproduce and provoke a robust immune response. Such vaccines often require only a single injection, increasing speed and convenience of administration.

A live attenuated vaccine for Rift Valley Fever virus already exists, a strain called MP-12. MP-12 produces a strong immune response in humans and livestock, but human safety trials of the vaccine have never been completed. Practical application of MP-12 faces other obstacles as well. For one thing, researchers worry that the vaccine retains a small amount of residual virulence. For another, they’re concerned that the antibodies MP-12 evokes are identical to those produced in response to infection by full-strength Rift Valley fever virus. In an outbreak, public health officials would be unable to tell animals vaccinated with MP-12 from naturally infected ones, making it impossible for them to map the epidemic’s spread and respond effectively.

To resolve these issues, Ikegami and his colleagues went to work on MP-12’s genome, focusing on a segment designated NSs. When a Rift Valley fever virus enters a cell, NSs produces proteins that function like saboteurs. They attack two of the cell’s key defense systems: the genetic mechanism that generates the antiviral protein interferon beta, and a protein called PKR, which suppresses viral protein production.

“We removed the NSs gene because we thought it would attenuate MP-12 further, and it would make it easy to differentiate infected from vaccinated animals — MP-12 without NSs wouldn’t produce any anti-NSs antibody, thus giving a different antibody response from wild-type Rift Valley fever virus,” Ikegami said.

Experiments with mice exposed to Rift Valley fever virus in UTMB’s Robert E. Shope, MD Biosafety Level 4 Laboratory confirmed that the NSs-less strain remained a highly effective vaccine. But Ikegami was not satisfied.

“The neutralizing antibody response was slightly decreased, and I thought we could do better if we retained some of the function of the NSs,” he said. To do this, the team introduced a gene for a “dominant negative PKR” — a molecule that would interfere with the cell-defending PKR protein, allowing the vaccine virus to multiply more freely. When they tested the new vaccine strain in mice, they found that it actually protected the animals better than MP-12.

“We got really good efficacy in mice, and we’re hoping it will translate well to large animals,” Ikegami said. “This has been a very successful project, with some great teamwork and major contributions from two postdocs, Olga Lihoradova and Birte Kalveram.”

Source:
ScienceDaily

HIV vaccine research could be revolutionized with mouse with human immune system

Wednesday, July 18th, 2012 (last updated)

One of the challenges to HIV vaccine development has been the lack of an animal model that accurately reflects the human immune response to the virus and how the virus evolves to evade that response. In the July 18 issue of Science Translational Medicine, researchers from the Ragon Institute of Massachusetts General Hospital (MGH), MIT and Harvard report that a model created by transplanting elements of the human immune system into an immunodeficient mouse addresses these key issues and has the potential to reduce significantly the time and costs required to test candidate vaccines.

“Our study showed not only that these humanized mice mount human immune responses against HIV but also that the ability of HIV to evade these responses by mutating viral proteins targeted by CD8 ‘killer’ T cells is accurately reflected in these mice,” says Todd Allen, PhD, senior author of the report. “For the first time we have an animal model that accurately reproduces critical host-pathogen interactions, a model that will help facilitate the development an effective vaccine for HIV.” Recent studies by Allen’s team and others have revealed that immune control of HIV is significantly limited by the ability of the virus to evade immune responses by rapidly mutating.

The traditional animal model for HIV research is the rhesus monkey, which can be infected with the related simian immunodeficiency virus (SIV). But differences in viral sequences between SIV and HIV, along with differences between the human and monkey immune systems, limit the ability of the SIV model to replicate directly key interactions between HIV and the human immune system. Development of an effective HIV vaccine will require a greater understanding of how human immune responses succeed or fail to control HIV.

The current study was designed to test the humanized BLT mouse, a model created by transplanting human bone marrow stem cells, along with other human tissue, into mice lacking a functioning immune system. Andrew Tager, MD, a co-author of the report and director of the MGH Humanized Mouse Program, explains, “Multiple researchers have contributed to dramatic improvements in the ability of humanized mice to model human diseases. Earlier studies with BLT mice performed at the University of Texas Southwestern Medical Center, the MGH and elsewhere have demonstrated that this particular humanized mouse model reproduces many aspects of the human immune response.”

Timothy Dudek, PhD, of the Ragon Institute, lead author of the current study, adds, “Unlike normal mice, these humanized mice can be infected with HIV. But there has been little evidence regarding whether they reproduce the interaction between HIV and the human immune system, particularly the development of specific immune responses that exert control over HIV by targeting critical regions of the virus.”

Tager’s team at the MGH Center for Immunology and Inflammatory Diseases created groups of humanized BLT mice using cells and tissues from human donors with different alleles, or versions, of the immune system’s HLA molecules, which flag infected cells for destruction by CD8 T cells. Particular HLA alleles, such as HLA-B57, are more common in individuals naturally able to control HIV, and some of the mice generated by Tager’s group expressed this important protective allele.

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Source:
RedOrbit & Science Translational Medicine

Looking for help in responding to vaccine-hesitant parents?

Wednesday, July 18th, 2012 (last updated)

Here you find science-based materials form respected organizations like American Academy of Pediatrics, CDC, Every Child by Two, etc.

Click here

Source:
immunize.org

Changing the face of global health: one boy gets his measles vaccine, another boy goes blind.

Tuesday, July 17th, 2012 (last updated)

On the first day our PATH team was in Madhya Pradesh, a large state in the heart of India, we met six-year-old Satish. He wore a brown stocking cap and knee-high pink socks and had huge dark eyes that could no longer see. The illness that struck him blind also left dark scars over much of his body. “Measles?” wondered the three doctors we were with.

On our second day, we traveled to the next village over, where women sat cross-legged in a crowded and lively courtyard with babies in their laps. It was the monthly immunization day.

Narendra, a one-year-old boy with wispy brown curls, was getting his measles vaccine and a spoonful of vitamin A. He squirmed and wailed at the pinch of the needle, but once it was over he was easily calmed by a packet of Orange Tiger Biscuits. At first he just enjoyed the sight of the bright colors of the wrapper. Then he found the cookie inside.

Measles is still serious

After witnessing what had happened to Satish, the measles vaccine Narendra received seemed like a godsend to me. The mothers in that courtyard were clearly convinced as well.

In places like the United States, where vaccines and treatment are common, we’ve forgotten that measles can lead to serious complications such as blindness. It’s still the leading cause of vaccine-preventable deaths in children worldwide, particularly in India, where almost three-fourths of the world’s measles deaths occurred in 2008 (the most recently available data).

In Madhya Pradesh, immunization rates for measles and other vaccine-preventable diseases were so low that PATH was asked to lend our expertise. We’re helping the state’s immunization program reach more children with better services by training frontline care workers, educating parents about the importance of vaccines, and ensuring that immunization days happen regularly and are well run.

Protection from a tragic fate

Regular immunization days weren’t around when Satish was a baby, and he missed a number of his childhood vaccines. On the day we visited, the doctors examined the boy, trying to discern the extent of his blindness. One of them held out a packet of cookies. Satish reached here and there, but couldn’t find it.

The doctors encouraged the boy’s mother, who is widowed, to take Satish to the district hospital. She was hesitant—missing even one day of work as a field laborer could leave the family hungry. It was a reminder of why bringing vaccines to villages is so important.

Immunization rates are up in Madhya Pradesh, and, thankfully, cases like Satish’s are increasingly rare. A dedicated group of PATH staff in India and their public health counterparts are making sure Narendra and children in hundreds of other villages are protected.

Source:
PATH

Vaccine success story: congenital rubella syndrome

Monday, July 16th, 2012 (last updated)

A newly released WHO document explains how vaccination has drastically reduced congenital rubella syndrome and describes the global strategy to achieve elimination.

An estimated 110 000 babies are born with congenital rubella syndrome every year. While the illness is generally mild in children, it has serious consequences in pregnant women causing fetal death or congenital defects.

Click here

Source:
WHO

Philippines to vaccinate 700,000 babies

Monday, July 16th, 2012 (last updated)

Philippine President Benigno Aquino III said in the beginning of July the government would vaccinate 700,000 babies this year to protect them from a virus that causes diarrhoea, a killer disease ravaging poor communities.

While diarrhoea is a preventable disease, Aquino said health authorities had struggled to stop outbreaks from happening with many poor communities having no access to basic medical care.

“In the Philippines alone, thousands of children suffer from diarrhoea each year, with over 3,500 cases leading to death,” Aquino said.

“For this year, 700,000 infants from families listed in our national household targeting system will be vaccinated,” he said.

He said the vaccines would address infections from rotavirus, the most common cause of severe diarrhoea in babies and children aged five and below.

According to the United Nations Children’s Fund (UNICEF), diarrhoea is the third leading cause of child illness and the fourth leading cause of deaths among children less than five years in the Philippines.

Source:
RTV Malacanang & Yahoo! News

Whooping cough making a comeback?

Sunday, July 15th, 2012 (last updated)

Becoming an epidemic in the northwest. Whooping cough has 1000 cases in Washington State. Although vaccines are in place to prevent these outbreaks, there are many vaccine exemptions, which may be the cause for a surge in the number cases. There was also an outbreak in California in 2010, responsible for 9000 hospital visits. Surely this condition should be relegated to the pages of history. What can we do to minimize our children’s exposure?

Source:
Insiders Health

Flu season spreads through Southeastern Australia

Sunday, July 15th, 2012 (last updated)

Southeastern Australia is experiencing a rise in influenza cases this year, with twice as many confirmed infections as the same time last year.

According to the National Center for Immunization Research and Surveillance, Australia averages more than 4,000 hospitalizations from influenza and 85 deaths each year. Vaccination may prevent infection or reduce the severity of symptoms of influenza.

“When there is a good match between the influenza strains in the vaccine and those causing current disease, the vaccine can prevent illness in about 70 to 90 percent of healthy children and adults,” the NCIRS said.

The Influenza Specialist Group, a not-for-profit group, has alerted the public to the presence of H3N2, which is a slightly different strain than the one in the vaccine. Approximately 98 percent of the cases diagnosed in Southeastern Australia have been the result of H3N2.

“The strain that’s in the vaccine almost certainly will provide some protection against the H3N2 strain that is circulating, but it’s not exactly the same,” Paddy Phillips, the chief medical officer of SA Health, said. “That may be contributing to the fact that we’re seeing more of that H3N2 strain.”

Officials said that people experiencing flu-like symptoms should seek medical attention. In 2010, the flu season began late with only 103 cases diagnosed by the same time this year. There have been 2,037 cases reported so far this year. There were 4,272 cases reported in 2010, only 500 fewer than last year’s total.

Source:
Vaccine News Daily

Nano-patch: the needle-free vaccine

Friday, July 13th, 2012 (last updated)

Professor Mark Kendall has developed a needle-free vaccine device.
The patch – which is smaller than a postage stamp – uses micro-projections made from dried vaccine.
A great way of delivering vaccine for those with a needle phobia.

Source:
NTD Television

Crucell’s community outreach program ‘Footprint’

Thursday, July 12th, 2012 (last updated)

Crucell launched a global corporate social responsibility program called ‘Footprint’ in 2009, with the aim of strengthening our employees’ engagement with our mission. Footprint gives teams of Crucell volun­teers the chance to visit disadvantaged communities where Crucell is helping to make a big difference to people’s lives. Teams have travelled to South Africa or Bangladesh to see for themselves what healthcare and vaccination really mean to communities battling with poverty and infectious diseases. To do their bit of help, in a direct and practical way, and to see the difference Crucell is making to the lives of people living in disadvantaged communities. We follow a group of Crucell volunteers in March 2012, visiting the remote areas of Bangladesh, and learn about their life-changing experiences.

Source:
Crucell Video