Vaccinology – Page 2 – Veterinary Sciences Tomorrow

A new study by Kansas State University veterinary diagnosticians finds that pets with out-of-date rabies vaccinations are very unlikely to develop the fatal disease if given a rabies booster immediately after exposure to the virus. The finding gives pet owners, veterinarians and public health officials new options when faced with the difficult situation of quarantining or even euthanizing a pet that has been exposed to the rabies virus, said Michael Moore, project manager of the Kanas State University Veterinary Diagnostic Laboratory. “This has the potential to save a lot of pets’ lives,” Moore said. “Our hope is that now animals with an out-of-date vaccination status that are exposed to rabies will be allowed to be handled the same as dogs and cats with up-to-date vaccinations. They will be given a booster and a 45-day observation at home.” Moore conducted the study with Rolan Davis, reference diagnostician of the Veterinary Diagnostic Lab; Derek Mosier, professor of diagnostic medicine and pathobiology; Christopher Vahl, assistant professor of statistics; and colleagues at the Statistical Intelligence Group LLC and Centers for Disease Control and Prevention. The findings appear in the Journal of the American Veterinary Medical Association study, “Comparison of anamnestic responses to rabies vaccination in dogs and cats with current and out-of-date vaccination status.” It is the first study to present scientific data for animals with out-of-date rabies vaccinations.

Each year the U.S. has around 6,000 documented cases of rabies, mostly in raccoons, skunks, bats and foxes. The disease is usually fatal for animals. Pets with out-of-date vaccinations that are exposed to the rabies virus are required to either stay in observed quarantine for six months — which can cost owners $5,000-$7,000 — or to be euthanized. “I get calls from a lot of people around the U.S. who are very sad because they had to euthanize their pet because they couldn’t afford the quarantine cost,” Moore said. “Even if an owner can afford the quarantine, they cannot see their pet for six months.” The study looked at 74 dogs and 33 cats with current and out-of-date rabies vaccinations. Most of the animals were one to two years out-of-date on their vaccines. A smaller segment was three to four years out-of-date.

Researchers studied the anamnestic antibody responses of the animals. They found that when an animal with an out-of-date vaccination was given a booster vaccination, the neutralizing antibodies in the animal’s blood rose, protecting the animal against exposure to the rabies virus. “Basically once an animal has been vaccinated, they can receive a booster if they are exposed to the rabies virus,” Moore said. “Then their chances for surviving that virus are very, very good.” The rabies booster is only effective if an animal has been given its initial rabies vaccination, Moore said. While conducting trials, researches also found that some manufacturers’ formulations for their one-year and three-year rabies vaccines were identical. In addition to the medical benefits, Moore said the findings might help clarify and shape the current guidelines for pets that are exposed to the rabies virus. “If you relate this to human health, humans are primed with an initial vaccination series and then have neutralizing antibodies checked from time to time,” Moore said. “If those antibodies fall below a certain level, we’re given a booster. While the vaccines are licensed for a certain number of years, the immune system doesn’t sync to a date on the calendar and shut down because it reached that particular date.”

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http://www.sciencedaily.com/releases/2015/01/150126095321.htm Original web page at Science Daily

In a study published in the journal Immunity, the researchers report that an investigational vaccine that elicited an immune response in an estimated 31 percent of participants was able to do so because of a particular antibody gene motif that is shared with rhesus macaques and other primates. When activated by the vaccine, the antibody gene makes it easy for the immune system to recognize and attack the HIV virus at a specific location on the outer coat of the virus. The finding helps further the understanding of how the vaccine candidate, tested in Thailand in a trial known as RV144, triggered an immune response that provided modest protection. The RV144 study is the only vaccine trial to show any efficacy, so it provides data for scientists to mine. Duke researchers have played a key role in an international collaboration that has discovered many important clues into why RV144 worked and what it will take to develop a more efficacious HIV vaccine. In their analysis, the researchers tracked the immune response in rhesus macaques that were immunized with a vaccine regimen similar to that used in the RV144 human trial in Thailand. The researchers found that the monkeys’ immune response was similar to what was seen in humans, and was actually the dominant response. “It turns out that this antibody response that can recognize this part of the HIV envelope is encoded in the genes present throughout primate development,” said lead author Kevin Wiehe, Ph.D. “We found it in almost every primate species we studied — macaques, gorillas, bonobos and lemurs. “When we found it in that many primate species, we then traced it back to when the common ancestor of humans and lemurs diverged — 87 million years ago. HIV has not been around that long, but other monkey retroviruses likely have, so this is an ancient antibody recognition motif that has been retained through evolution that is also used to recognize HIV.” Wiehe and colleagues said the ancient genetic trait enables primates to produce antibodies easily to retrovirus proteins, and presents an opportunity to seek ways of boosting this ability or building upon it to create an effective vaccine. The drawback, however, is that this specific response might compete with broadly neutralizing antibodies that can defuse the virus regardless of how it mutates. “The place on the envelope to which antibodies were made in the RV144 trial is also a site of rare broadly neutralizing antibody binding,” said senior author Barton F. Haynes, director of the Duke Human Vaccine Institute. “What we have found is that the mode of making the non-broadly neutralizing antibodies is so dominant, that it is conserved throughout primate development over millions of years. “Thus, our primate immune systems have been trained over many years to respond in this manner,” Haynes said. “To make broadly neutralizing antibodies, we need to bypass this remarkably highly conserved mode of antibody response to train our immune systems to respond in a new manner. That is where our current studies are focused.” Wiehe said eliciting broadly neutralizing antibodies remains one key goal of HIV vaccine development, because the HIV virus mutates so rapidly. “We need antibodies that can recognize multiple strains of the virus,” he said. http://www.sciencedaily.com/ Science Daily http://www.sciencedaily.com/releases/2015/01/150115152845.htm Original web page at Science Daily