Vector Reference Laboratory, Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, National Health Laboratory Services, Johannesburg, South Africa.
Wits Research Institute for Malaria, School of Pathology, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, Johannesburg, South Africa.
Malar J. 2022 Sep 5;21(1):254. doi: 10.1186/s12936-022-04276-6.
South Africa has set a mandate to eliminate local malaria transmission by 2023. In pursuit of this objective a Sterile Insect Technique programme targeting the main vector Anopheles arabiensis is currently under development. Significant progress has been made towards operationalizing the technology. However, one of the main limitations being faced is the absence of an efficient genetic sexing system. This study is an assessment of an An. arabiensis (AY-2) strain carrying the full Y chromosome from Anopheles gambiae, including a transgenic red fluorescent marker, being introgressed into a South African genetic background as a potential tool for a reliable sexing system.
Adult, virgin males from the An. arabiensis AY-2 strain were outcrossed to virgin females from the South African, Kwazulu-Natal An. arabiensis (KWAG strain) over three generations. Anopheles arabiensis AY-2 fluorescent males were sorted as first instar larvae (L1) using the Complex Object Parametric Analyzer and Sorter (COPAS) and later screened as pupae to verify the sex. Life history traits of the novel hybrid KWAG-AY2 strain were compared to the original fluorescent AY-2 strain, the South African wild-type KWAG strain and a standard laboratory An. arabiensis (Dongola reference strain).
The genetic stability of the sex-linked fluorescent marker and the integrity and high level of sexing efficiency of the system were confirmed. No recombination events in respect to the fluorescent marker were detected over three rounds of introgression crosses. KWAG-AY2 had higher hatch rates and survival of L1 to pupae and L1 to adult than the founding strains. AY-2 showed faster development time of immature stages and larger adult body size, but lower larval survival rates. Adult KWAG males had significantly higher survival rates. There was no significant difference between the strains in fecundity and proportion of males. KWAG-AY2 males performed better than reference strains in flight ability tests.
The life history traits of KWAG-AY2, its rearing efficiency under laboratory conditions, the preservation of the sex-linked fluorescence and perfect sexing efficiency after three rounds of introgression crosses, indicate that it has potential for mass rearing. The potential risks and benefits associated to the use of this strain within the Sterile Insect Technique programme in South Africa are discussed.
南非设定了在 2023 年消除本地疟疾传播的任务。为了实现这一目标，目前正在开发针对主要传播媒介按蚊属阿拉伯亚种的不育昆虫技术计划。在使该技术投入运行方面取得了重大进展。然而，面临的主要限制之一是缺乏有效的遗传性别鉴定系统。本研究评估了一种携带按蚊属冈比亚亚种全长 Y 染色体的按蚊属阿拉伯亚种（AY-2）品系，包括一种转基因红色荧光标记物，作为一种可靠性别鉴定系统的潜在工具，被引入南非遗传背景。
将按蚊属阿拉伯亚种 AY-2 品系的成年、处女雄性与来自南非夸祖鲁-纳塔尔省的按蚊属阿拉伯亚种（KWAG 品系）的处女雌性进行三代杂交。按蚊属阿拉伯亚种 AY-2 荧光雄性作为第一龄幼虫（L1）通过复杂物体参数分析器和分选器（COPAS）进行分选，然后作为蛹进行筛选以验证性别。新型杂交 KWAG-AY2 菌株的生活史特征与原始荧光 AY-2 菌株、南非野生型 KWAG 菌株和标准实验室按蚊属（Dongola 参考菌株）进行了比较。
证实了性连锁荧光标记的遗传稳定性以及系统的完整性和高效性别鉴定效率。在三轮回交杂交中，未检测到与荧光标记物有关的重组事件。KWAG-AY2 的 L1 到蛹和 L1 到成虫的孵化率和存活率均高于起始菌株。AY-2 的幼期发育时间较快，成虫体型较大，但幼虫存活率较低。成年 KWAG 雄性的存活率明显较高。各菌株的繁殖力和雄性比例没有显著差异。KWAG-AY2 雄性在飞行能力测试中的表现优于参考菌株。
KWAG-AY2 的生活史特征、其在实验室条件下的饲养效率、性连锁荧光的保存以及三轮回交杂交后的完美性别鉴定效率表明，它具有大规模饲养的潜力。讨论了在南非不育昆虫技术计划中使用该菌株的潜在风险和益处。
