Archive for February, 2011

An Alzheimer’s Vaccine in a Nasal Spray?

Monday, February 28th, 2011 (last updated)

One in eight Americans will fall prey to Alzheimer’s disease at some point in their life, current statistics say. Because Alzheimer’s is associated with vascular damage in the brain, many of them will succumb through a painful and potentially fatal stroke.

But researchers led by Dr. Dan Frenkel of Tel Aviv University’s Department of Neurobiology at the George S. Wise Faculty of Life Sciences are working on a nasally-delivered 2-in-1 vaccine that promises to protect against both Alzheimer’s and stroke. The new vaccine repairs vascular damage in the brain by rounding up “troops” from the body’s own immune system.

And in addition to its prophylactic effect, it can work even when Alzheimer’s symptoms are already present. The research on this new technology was recently accepted for publication in the journal Neurobiology of Aging.

A natural way to fight Alzheimer’s

“Using part of a drug that was previously tested as an influenza drug, we’ve managed to successfully induce an immune response against amyloid proteins in the blood vessels,” says Dr. Frenkel, who collaborated on this project with Prof. Howard L. Weiner of Brigham and Women’s Hospital, Harvard Medical School. “In early pre-clinical studies, we’ve found it can prevent both brain tissue damage and restore cognitive impairment,” he adds.

Modifying a vaccine technology owned by Glaxo Smith Kline, a multinational drug company, Tel Aviv University’s new therapeutic approach activates a natural mechanism in our bodies that fights against vascular damage in the brain.

The vaccine, Dr. Frenkel explains, activates macrophages — large proteins in the body that swallow foreign antigens. When the vaccine activates large numbers of these macrophages, they clear away the damaging build-up of waxy amyloid proteins in our brain’s vascular system.

Animal models showed that once these proteins are cleared from the brain, further damage can be prevented, and existing damage due to a previous stroke can be repaired.

A new road to an Alzheimer’s cure?

Could the breakthrough lead to both a vaccine and a long-sought cure for Alzheimer’s disease? “It appears that this could be the case,” says Dr. Frenkel, who worked on the study with his doctoral student Veronica Lifshitz and master degree students Ronen Weiss and Tali Benromano. “We’ve found a way to use the immune response stimulated by this drug to prevent hemorrhagic strokes which lead to permanent brain damage,” he says.

Dr. Frenkel believes that this approach, when applied to a human test population, will be able to prevent the downward health spiral of Alzheimer’s and dementia. So far the vaccine has shown no signs of toxicity in animal models. Dr. Frenkel is hopeful that this new approach could lead to a cure, or at least an effective treatment, for the vascular dementia found in 80% of all people with Alzheimer’s.

Nanoparticles That Mimic Viruses Can Stimulate Long Lasting Immunity

Friday, February 25th, 2011 (last updated)

Vaccine scientists say their “Holy Grail” is to stimulate immunity that lasts for a lifetime. Live viral vaccines such as the smallpox or yellow fever vaccines provide immune protection that lasts several decades, but despite their success, scientists have remained in the dark as to how they induce such long lasting immunity.

Scientists at the Emory Vaccine Center have designed tiny nanoparticles that resemble viruses in size and immunological composition and that induce lifelong immunity in mice. They designed the particles to mimic the immune-stimulating effects of one of the most successful vaccines ever developed – the yellow fever vaccine. The particles, made of biodegradable polymers, have components that activate two different parts of the innate immune system and can be used interchangeably with material from many different bacteria or viruses.

The results are described in this week’s issue of Nature.

  1. “These results address a long-standing puzzle in vaccinology: how do successful vaccines induce long lasting immunity?” says senior author Bali Pulendran, PhD, Charles Howard Candler professor of pathology and laboratory medicine at Emory University School of Medicine and a researcher at Yerkes National Primate Research Center.
  2. “These particles could provide an instant way to stretch scarce supplies when access to viral material is limited, such as pandemic flu or during an emerging infection. In addition, there are many diseases, such as HIV, malaria, tuberculosis and dengue, that still lack effective vaccines, where we anticipate that this type of immunity enhancer could play a role.”
  3. One injection of the live viral yellow fever vaccine, developed in the 1930s by Nobel Prize winner Max Theiler, can protect against disease-causing forms of the virus for decades. Pulendran and his colleagues have been investigating how humans respond to the yellow fever vaccine, in the hopes of imitating it.
  4. Several years ago, they established that the yellow fever vaccine stimulated multiple Toll-like receptors (TLRs) in the innate immune system. TLRs are present in insects as well as mammals, birds and fish. They are molecules expressed by cells that can sense bits of viruses, bacteria and parasites and can activate the immune system. Pulendran’s group demonstrated that the immune system sensed the yellow fever vaccine via multiple TLRs, and that this was required for the immunity induced by the vaccine.
  5. “TLRs are like the sixth sense in our bodies, because they have an exquisite capacity to sense viruses and bacteria, and convey this information to stimulate the immune response,” Pulendran says. “We found that to get the best immune response, you need to hit more than one kind of Toll-like receptor. Our aim was to create a synthetic particle that accomplishes this task.”

More than 21,000 in U.S. caught whooping cough in 2010

Thursday, February 24th, 2011 (last updated)

According to U.S. health officials, over 21,000 people in the United States were infected with whooping cough in 2010, which represents the highest number of cases since 2005.

Most of the cases of infection were in children and teens.

Health officials are confused by the increase in cases, especially since the whooping cough vaccine appears to be highly effective in children.

Whooping cough, also known as pertussis, starts out with cold-like symptoms but leads to intense coughing fits that can occur sporadically for weeks. Whooping cough led to at least 26 deaths in the United States last year.

Contagious adolescents can be a threat to vulnerable infants, because while 95 percent of children have had at least three shots against whooping cough, whooping cough vaccines for adults and adolescents were not licensed in the US until 2005. As a result, vaccination rates for these groups are much lower – one study even had adults pegged as low as a six percent immunization rate against pertussis.

It is recommended that all adults who are around infants receive the whooping cough vaccine.

Worldwide, there are 30 to 50 million cases of pertussis with around 300,000 deaths every year, the Centers for Disease Control reports. The disease can be life threatening for infants. Over 50 percent of infants under one year of age who get the disease must be hospitalized

International Vaccine Institute Announces Launch Of Dengue Vaccine Initiative

Friday, February 11th, 2011 (last updated)

The International Vaccine Institute (IVI) announced the launch of the Dengue Vaccine Initiative (DVI), in collaboration with the Sabin Vaccine Institute (Sabin), the Johns Hopkins University (JHU), and the World Health Organization (WHO), to support development of vaccines to control dengue fever, a widespread and expanding hemorrhagic fever that is endemic in most tropical and subtropical regions of the world.

Through a $6.9 million grant from the Bill & Melinda Gates Foundation, DVI will accelerate the development and utilization of safe, affordable and broadly protective vaccines to combat dengue, a mosquito-borne infection which causes severe flu-like symptoms, and its potentially lethal complication dengue hemorrhagic fever, characterized by bleeding, plasma fluid leakage, and in severe cases shock and death. Each year, an estimated 2 million people with dengue hemorrhagic fever require hospitalization representing a significant burden on the fragile healthcare systems of developing and endemic nations.

“We are extremely grateful for the Gates Foundation’s continued support of our critical work to promote the development of life-saving dengue vaccines and ensure their effective introduction. Dengue is an infection whose burden has increased sharply around the world,” said Dr. John Clemens, Director-General of IVI. “The global dengue community is on the eve of many important breakthroughs in dengue research and development, and I believe that we’ll make significant progress in controlling dengue within the decade.”

An estimated 3.6 billion individuals (55% of the world’s population) are at risk of contracting dengue, an infection caused by four distinct, yet closely related viruses. Recovery from one strain of dengue confers lifelong immunity against the infecting strain but increases the risk for development of hemorrhagic fever, shock, and death following infection from the other three strains.

“Development and use of a dengue vaccine represents the best hope of preventing cases, deaths and economic losses,” said Dr. Ciro de Quadros, Executive Vice President of Sabin. “There are very few places that dengue does not impact. The infection is endemic in more than 100 countries across the globe and incidence of infection in typically unexpected places is increasingly common.”

Current methods are limited to vector control, which have been largely ineffective at controlling dengue with the number of cases and geographic reach of the infection increasing dramatically each year. According to the WHO, the incidence of dengue has increased 30-fold over the last 50 years with 50 million dengue infections now occurring worldwide each year.

Further investigation is warranted concerning narcolepsy and vaccination against influenza (H1N1) 2009

Thursday, February 10th, 2011 (last updated)

This week, the World Health Organization (WHO) reported that 12 countries report suspected cases of narcolepsy linked to swine flu H1N1 vaccinations, especially in children and adolescents ages four to 19. But WHO advisors have not changed their position: they still recommend people get vaccinated anyway, saying the benefits outweigh the relatively small risk.

“The committee agrees that further investigation is warranted concerning narcolepsy and vaccination against influenza (H1N1) 2009 with Pandemrix and other pandemic H1N1 vaccines,” the WHO said. The European Medicines Agency is also looking into the possible link.

Pandemrix is not a type of H1N1 vaccine being used in the United States, because it contains an immune-boosting compound not approved for flu shots in the US.

WHO’s Global Advisory Committee on Vaccine Safety raised concerns about narcolepsy after reviewing data from a Finnish study which found children injected with the GlaxoSmithKline Pandemrix swine flu vaccine were nine times more likely to contract narcolepsy than those who were not vaccinated. Finland health officials say that during 2009-2010, that country had 60 reports of children and adolescents developing narcolepsy, and 52 of them had received the flu vaccine Pandemrix. Statistically, scientists agree that each report of an adverse event represents many more cases that are never reported.

According to the National Institutes of Health, narcolepsy is a chronic neurological disorder that causes people to have irresistible bouts of sleep at various times throughout the day. Other frequent symptoms include “cataplexy, or the sudden loss of voluntary muscle tone; vivid hallucinations during sleep onset or awakening; and brief episodes of total paralysis at the beginning or end of sleep.”

Can Breastfeeding Transmit Yellow Fever After Maternal Vaccination?

Tuesday, February 8th, 2011 (last updated)

A five-week old infant most likely contracted a vaccine strain of yellow fever virus through breastfeeding, according to a case report published in CMAJ (Canadian Medical Association Journal).

“Until recently, avoidance of vaccination of breastfeeding women with yellow fever vaccine had been based on theoretical grounds only,” writes Dr. Susan Kuhn, with coauthors. “We report the probable transmission of vaccine strain of yellow fever virus from a mother to her infant through breastfeeding,” which supports current recommendations for breastfeeding mothers to avoid the vaccine.

The yellow fever vaccine is a live-virus vaccine that has been used since the 1940s.

When the infant was 10 days old the mother received pre-travel advice and travel vaccinations, including one for yellow fever. Subsequently, they traveled to Venezuela for one week and breastfeeding was continued. The infant did not receive vaccinations.

“The previously healthy five-week old infant male presented to the hospital with a two-day history of fever and irritability,” write the authors. “The day before his admission, he had been noted to have focal seizures on alternating sides.” Testing of the spinal fluid revealed evidence of recent infection with the yellow fever virus. Given that the travellers elected to stay in urban Venezuela where yellow fever is not known to be a risk, the authors concluded that the likely explanation was transmission of the yellow fever vaccine strain through breastfeeding.

The baby showed no sign of insect bites, had not been in contact with sick people, was not exposed to animals in Canada or elsewhere, had no history of herpes infections in family members and had not had any vaccinations prior to his symptoms.

“This probable case of yellow fever virus further supports the current recommendations for avoidance of yellow fever vaccination in lactating mothers of infants under nine months of age,” write the authors. “While there may be situations in which the mother will have unavoidable and significant risk of yellow fever exposure, the risk to the infant due to maternal vaccination must be weighed against the risk of wild-type virus infection.”

The authors conclude that travelling women should adjust their plans to reduce or limit their risk of exposure or postpone their trip entirely until their infant is no longer breastfeeding or is old enough to be vaccinated.

HPV Vaccine Works For Boys

Sunday, February 6th, 2011 (last updated)

The vaccine for human papillomavirus (HPV) can prevent 90 percent of genital warts in men when offered before exposure to the four HPV strains covered by the vaccine, according to a new multi-center study led by H. Lee Moffitt Cancer Center and UCSF. The four-year, international clinical trial, which also found a nearly 66 percent effectiveness in the general population of young men regardless of prior exposure to these strains, provides the first reported results of using the HPV vaccine as a prophylactic in men.

Initial data from this study informed the Food and Drug Administration’s decision to approve the vaccine for boys in 2009 to prevent warts, while results from a substudy led the FDA to expand approval late last year to prevent anal cancer. Findings can be found in the Feb. 3 issue of the New England Journal of Medicine, or online at www.nejm.org. While the HPV vaccine was approved in 2006 for girls to prevent cervical cancer, the vaccine’s benefit for young men was not initially addressed. Yet infection and diseases caused by HPV are common in men, the researchers said, including genital warts, which are one of the leading sexually transmitted diseases (STD) for which treatment is sought nationwide. The Centers for Disease Control and Prevention estimate that half of all sexually active Americans will get HPV at some point in their lives. “This is an exciting development in the STD world,” said Joel Palefsky, MD, a UCSF professor of medicine who co-led the research along with epidemiologist Anna R. Giuliano, PhD, from the H. Lee Moffitt Cancer Center and Research Institute, in Tampa, FL. “It shows that if we vaccinate males early enough, we should be able to prevent most cases of external genital warts in this population.”

While warts are often considered an annoyance, rather than a life-threatening disease such as cervical cancer, Palefsky noted that warts are a common problem in young people and are often associated with depression, social stigma and loss of self-esteem. Complications of wart treatments are also quite common, he said.

The double-blind study included 4,065 healthy men aged 16-26 years, spanning 71 sites in 18 countries. Of those patients, 85 percent reported having exclusively female sexual partners, with the remainder self-identified as having sex with men.

The men were tested at the onset of the trial for previous exposure to each strain and were randomly selected to receive either a placebo or a vaccine that targeted HPV strains 6, 11, 16 and 18. Men with a history of anal or genital warts or lesions were excluded. Participants then received six follow-up examinations over the following three years to assess the vaccine’s effectiveness.

In addition to preventing warts, the vaccine also effectively prevented HPV-persistent infection in 86 percent of the participants without previous exposure.

“This is the first study to show that this vaccine works in boys,” Giuliano said. “As long as we have a poor record of vaccinations in girls, boys should also be vaccinated.”

Vaccinating boys also should help prevent HPV transmission to women, as well as transmission from men to men, she said, and help reduce the incidence of the virus throughout the general population. This could be particularly significant, Palefsky added, since only 30 to 40 percent of teenage girls in the U.S. have received even one of the three recommended doses of the vaccine.

The authors noted that while they find it likely that the prevention of HPV infection and disease in men will have additional benefits, such as preventing anal, genital and throat cancers, these benefits need to be directly demonstrated through further clinical trials.

Inhaled measles vaccine developed

Wednesday, February 2nd, 2011 (last updated)

Researchers have developed a new live attenuated vaccine for measles that can be inhaled. Scientists from the Johns Hopkins Bloomberg School of Public Health and the University of Colorado have been working on and successfully tested the dry powder that is thought to have potential to contribute to a high level of sustained measles vaccination coverage.

Current measles vaccinations require two injections in order to provide full immunity. One is given at nine to 12 months of age and another later in childhood.

Special training is also needed to administer the current vaccine, which needs refrigeration in the field after it is reconstituted from a powdered form, RedOrbit.com reports. This preparation makes it difficult to use the measles vaccine in the developing world, where vaccine coverage remains limited.

According to the new study, published in the January 31 edition of the journal PNAS, the dry powder vaccine provided a group of macaques protection from measles in a single aerosol dose using one of two inhalers, the PuffHaler or the BD Solovent. No adverse side effects were seen.

“An effective dry powder vaccine would be tremendously helpful in less developed regions where resources are limited,” Diane E. Griffin, senior author of the study from the Bloomberg School of Public Health, said, RedOrbit.com reports. “This vaccine can be shipped as powder and does not require reconstitution or special training to administer, which could greatly increase the ease and safety of measles vaccination worldwide.”

Human trials for the powder vaccine are being developed in India.