Godsey Marvin S, Savage Harry M, Burkhalter Kristen L, Bosco-Lauth Angela M, Delorey Mark J
Arboviral Diseases Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521 (
J Med Entomol. 2016 Sep 1;53(5):1226-1233. doi: 10.1093/jme/tjw080.
Heartland virus (HRTV; Bunyaviridae: Phlebovirus) is a recently described cause of human illness in the United States. After field studies conducted in 2012 implicated Amblyomma americanum (L.) as a vector of HRTV, we initiated experiments to assess the vector competence of A. americanum. Larval and nymphal ticks were immersed in high-titered suspensions of HRTV, and then tested for virus at various intervals postimmersion. In a later trial larval ticks were immersed in HRTV, followed by engorgement on a rabbit. A subset of postmolt nymphs was tested for HRTV to document transstadial transmission. Putatively infected nymphs were cofed with uninfected colony larvae to assess nonviremic transmission. In another trial, nymphs were fed on a rabbit and allowed to molt to the adult stage. Male and female ticks fed and mated upon a rabbit, and females were allowed to oviposit. Male and spent female ticks were tested for HRTV, and offspring of infected females were tested to assess vertical transmission. Infection rates of ≤50% were observed in immersed larvae and nymphs tested at intervals following immersion. Transstadial transmission from larvae to nymphs and then to adults was documented. HRTV was detected in a pool of nymphs molted from uninfected larvae cofed with infected nymphs. Vertical transmission of HRTV was observed in progeny of infected females. Infected females took longer to oviposit and produced fewer offspring. Serologic conversions (without viremia) in rabbits fed upon by immersed larvae or transstadially infected ticks indicate horizontal transmission of HRTV.
心脏地带病毒（HRTV；布尼亚病毒科：白蛉病毒属）是美国近期发现的一种人类致病源。2012年进行的野外研究表明美洲钝眼蜱（L.）是HRTV的传播媒介后，我们开展了实验以评估美洲钝眼蜱的媒介能力。将幼蜱和若蜱浸入高滴度的HRTV悬液中，然后在浸入后的不同时间间隔检测病毒。在随后的试验中，将幼蜱浸入HRTV中，然后让其在兔体上饱血。对一部分蜕化后的若蜱检测HRTV，以证明经卵传递。将推定感染的若蜱与未感染的群体幼蜱共同取食，以评估非病毒血症传播。在另一项试验中，让若蜱在兔体上取食并蜕化为成虫。在兔体上取食并交配的雌雄蜱，让雌蜱产卵。检测雄蜱和已产卵的雌蜱是否感染HRTV，并检测感染雌蜱的后代以评估垂直传播。在浸入后不同时间间隔检测的浸入幼蜱和若蜱中，观察到感染率≤50%。记录了从幼蜱到若蜱再到成虫的经卵传递。在与感染若蜱共同取食的未感染幼蜱蜕化的若蜱群体中检测到HRTV。在感染雌蜱的后代中观察到HRTV的垂直传播。感染雌蜱产卵所需时间更长，且产卵量更少。被浸入幼蜱或经卵感染蜱取食的兔出现血清学转换（无病毒血症），表明HRTV可水平传播。
