Lassa virus is endemic in a large area of sub-Saharan Africa, and exhibits a large amount of genetic diversity. Of the four currently recognized lineages, lineages I–III circulate in Nigeria, and lineage IV circulates in Sierra Leone, Guinea, and Liberia. However, several newly detected lineages have been proposed. LASV genetic diversity may result in differences in pathogenicity or response to medical countermeasures, necessitating the testing of multiple lineages during the development of countermeasures and diagnostics.

Logistical and biosafety concerns can make it difficult to obtain representative collections of divergent LASV clades for comparison studies. For example, lack of a cold chain in remote areas, or shipping restrictions on live viruses can prevent the dissemination of natural virus isolates to researchers. Reverse genetics systems that have been developed for LASV can facilitate acquisition of hard-to-obtain LASV strains and enable comprehensive development of medical countermeasures.

Lassa病毒在撒哈拉以南非洲的大部分地区是地方性的，并表现出大量的遗传多样性。在目前公认的四个血统中，一，三血统在尼日利亚流通，四血统在塞拉利昂，几内亚和利比里亚流通。但是，已经提出了几种新近检测到的血统。LASV的遗传多样性可能会导致致病性差异或对医学对策的反应，因此在对策和诊断方法的开发过程中必须对多个谱系进行测试。

后勤和生物安全问题可能会使得很难获得代表性的LASV进化枝的代表性收藏品进行比较研究。例如，偏远地区缺乏冷链，或者活病毒的运输限制都可能阻止天然病毒分离株向研究人员传播。为LASV开发的逆向遗传学系统可以促进难以获得的LASV菌株的获取，并能够全面开发医学对策。