LOS ANGELES, June 27 (Xinhuanet)-- A vaccine against Lassa fever has protected monkeys in experiment from infection with lethal doses of Lassa virus, US and Canadian scientists reported on Monday.

    The study, published in the journal Public Library of Science (PLoS) Medicine, could eventually lead to development of a vaccine for human use, the researchers said.

    The Lassa fever, transmitted to humans from rodents that carry the virus, is common in parts of West Africa where it causes a significant amount of death and disability among the population.

    Recently, some travelers died of hemorrhagic fever in the US and Europe after being infected with this virus in West Africa. The reported cases aroused panic, but there is no preventive measure available currently to halt the spread of Lassa fever other than rodent control in affected areas.

    In this new research, lead investigators Thomas Geisbert of the US Army Medical Research Institute of Infectious Diseases (USAMRIID)and Heinz Feldmann and Steven Jones of the Public Health Agency of Canada (PHAC) developed the vaccine using a non-pathogenic form of vesicular stomatitis virus, or VSV, as a carrier.

    The researchers inserted genetic material from the Lassa virus,which express the Lassa viral glycoprotein. The team then immunized four rhesus macaques with a single dose of the Lassa vaccine, while two monkeys received only the VSV "carrier" virus.

    Four weeks later, all six animals were experimentally infected with a lethal dose of Lassa virus. The four vaccinated monkeys survived with no signs of clinical illness, while the two control animals died.

    "Our data suggest that the Lassa vaccine candidate based on recombinant vesicular stomatitis virus is safe and highly efficacious in a relevant animal model that faithfully reproduces human disease," their paper said.

    "This is the first vaccine platform shown to completely protect nonhuman primates from Lassa virus," said Geisbert.

    Earlier this month, the same team reported similar VSV vaccines against Ebola and Marburg viruses. The researchers are hopeful that the VSV strategy could have utility against other hemorrhagic fevers as well.

    "Lassa fever poses a huge public health threat in Western Africa," said Feldmann in a statement.

    "While the mortality rate of this virus is not as high as withsome viral hemorrhagic fevers, there are many more cases of Lassa fever and a great number of survivors are permanently affected by complications such as hearing loss, so this vaccine may have a much broader application."

    A vaccine against the Lassa virus could help to control outbreaks of the disease in Africa and protect health care and laboratory workers. Previous attempts to develop Lassa vaccines were partially successful, but none completely protected nonhuman primates against lethal doses of the virus, according to the researchers.

    While these early results are promising, further testing will need to be conducted. Some issues that must be resolved before the vaccine can be tested in humans are the safety of the VSV virus, how long the vaccine protects after the shot, and whether it is active against different genetic strains of the Lassa virus, the researchers said. Enditem