Scientists published a paper last month on the development of an animal model that showed the same disease signs that humans do when exposed to the Nipah virus.

Nipah and Hendra viruses, which are closely related, are found in Pteropid fruit bats (flying foxes) and are capable of causing illness and death in both domestic animals and humans.

In experiments carried out in a high-level security and safety facility at the US Army Medical Research Institute of Infectious Diseases (USAMRIID), researchers demonstrated that when African Green Monkeys were exposed to the Nipah virus they induced disease signs that were essentially identical to those observed in people when infected by this deadly virus. This finding is important because it provides a needed platform for the evaluation and licensure of either passive and active immunization or therapeutic strategies for human use, according to the study.

A collaborative research team from the Uniformed Services University of the Health Sciences (USU), the National Emerging Infectious Diseases Laboratories Institute, the Department of Microbiology at Boston University School of Medicine, and USAMRIID released the findings on the animal model in a study last month, Development of an Acute and Highly Pathogenic Nonhuman Primate Model of Nipah Virus Infection. The full study is available at: http://dx.plos.org/10.1371/journal.pone.0010690.

The experiments were supported by the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health.

Nipah and Hendra

The natural reservoir for Hendra virus is thought to be flying foxes (bats of the genus Pteropus) found in Queensland, Australia. The Hendra virus typically infects horses, and humans can contract the virus from horses. Deaths in Australia have been reported over the years of people who contracted the virus from infected horses.

Bats of the genus Pteropus are also a source for the Nipah virus. Nipah virus was first recognized in Malaysia and Singapore in 1998-99 when the virus spilled over from a bat reservoir into pig farms, further spreading the virus to pigs and humans.

One concern is that these viruses could be used as potential bioterror agents aimed at harming livestock and humans. “Nipah in particular is as much of a concern as a potential bioterror agent as Ebola is, in terms of the pathogenesis of the virus,” said study corresponding author Christopher C Broder, PhD, USU professor of microbiology.

There are currently no licensed and approved vaccines or therapeutics for prevention and treatment of disease caused by these viruses. However, Broder said that the African Green Monkey model is facilitating their work in developing therapeutics and vaccines. “We are now at the stage where we are able to test our antibody therapeutics, our post exposure therapeutics as well as our vaccine candidates, and those studies are ongoing now.”

In addition to the work in developing human products, the team is also working with Australian researchers who are interested in a vaccine to protect horses from the Hendra virus.

Broder explained that the development of the African Green Monkey model is an important step in facilitating eventual FDA approval for Nipah and Hendra therapeutics and vaccines for humans, since researchers will have to have evaluation data from at least two different animal model systems. The researchers have already reported evidence that a human monoclonal antibody therapy against Nipah virus could be given following lethal infection in a ferret model of Nipah virus and have demonstrated that a protein component of the virus can also serve as a successful vaccine. “What we want to do now that we have this animal model is to show that we can do the same thing that we did in the ferret.”

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