拉沙热：新动物模型

科学家最近已成功把常见的绒猴作为新的供拉沙热研究的动物模型。拉沙热在西非流行，该病毒每年可杀死成千上万的人。

绒猴是一种小型灵长类动物，完全成熟后只有约1磅重，但是在许多遗传学和生理学上与人类非常接近。使用绒猴的一个优点就是此动物对拉沙病毒感染后的反应完全与人类对该病毒的反应类似。
对绒猴的研究可加快对拉沙热病毒疫苗的研究，包括已研发的疫苗以待动物模型的检测，病毒学和免疫学专家Jean Patterson解释道。

目前，在马里兰大学生物技术中心已研制的拉沙病毒疫苗已在绒猴身上检测。“拥有这种动物模型比起还未拥有时，测试疫苗有效性的周期将大为缩短。”Ricardo Carrion说，“并且因为这种动物模型比已存的动物模型对拉沙病毒的反应更加真实，所以它是一种优先的动物模型。”

拉沙热是一种病毒引起的疾病，主要发生在西非，通过大鼠传播，这种啮齿类动物能在有人类居住的环境下快速繁殖。仅20%的感染拉沙病毒的人会出现严重的症状。对那些患病的人来说，死亡率在15-20%，而对孕妇来说，死亡率会升至60%。如同人类，绒猴患病后的20天内将会死亡。而对于恢复的病人来说，30-40%的人会丧失听力并造成肝脏损伤。

拉沙热同样可以导致严重的免疫系统抑制，这也是现今对绒猴疫苗研究的一个方向。“孕妇的死亡率如此高是因为其已经处于免疫抑制状态。” Patterson解释道。


Lassa Fever: New Animal Model

Scientists have developed the common marmoset monkey as a new animal model for Lassa fever research. Lassa fever is endemic to West Africa, the virus kills thousands of people each year.The marmoset is a small primate that weighs about one pound when fully grown, but it has many genetic and physiological similarities to humans. An advantage of using marmosets is that the animal’s response to Lassa infection completely mimics the response found in people who develop symptoms.
 
The availability of the marmoset for this research is expected to speed the testing of potential vaccines against Lassa fever, including a number of candidate vaccines that already have been developed and are waiting on a model like this for testing, said Jean Patterson n, chairman of the Department of Virology and Immunology at Southwest Foundation for Biomedical Research (SFBR). 

Already, the scientists have been working with marmosets at SFBR to test a promising Lassa fever vaccine developed at the University of Maryland Biotechnology Institute. “Having this model will allow investigators to test their vaccines more quickly than they would be able to without it,” Ricardo Carrion Jr. said. “And because it mimics the human response to Lassa more faithfully than existing models, it might become the preferred model.” 

Lassa fever is a viral illness that occurs in West Africa, spread by the “multimammate rat,” known for frequent breeding and a tendency to colonize where people live. Only about 20 percent of people infected with Lassa develop severe symptoms. Of those who get sick, the mortality rate is from 15-20 percent, but the mortality rate rises to 60 percent for those who are pregnant. Like humans, marmosets that die from the disease do so within 20 days of becoming ill. Of those people who recover, 30-40 percent suffer hearing loss and liver damage. 

Lassa fever also causes a marked suppression of the immune system, an aspect of the disease that the researchers are tracking with the current marmoset vaccine study. “Pregnant women have such a high mortality rate from Lassa because pregnancy already causes immunosuppression, and Lassa compounds it,” Patterson said.