Yates J A, Schmitz K A, Nelson F K, Rajan T V
Department of Biological Sciences, Oakland University, Rochester, Michigan 48309.
J Parasitol. 1994 Dec;80(6):891-4.
Shipment of infective-stage filarial larvae (L3s) usually has been accomplished by transporting living infected vectors or L3s cryopreserved in liquid nitrogen. Our objective was to find culture conditions for transporting L3s that would promote survival of Brugia malayi larvae without altering their capacity to infect susceptible animals. In preliminary studies we observed that Ham's nutrient mixture F-12, with antibiotics and 1% fetal calf serum, could support L3s without apparent development for at least 10 days. In order to evaluate the effect of culture temperatures on infectivity, fresh L3s were divided into groups that were either immediately injected into jirds (infectivity control) or incubated for 24, 48, or 120 hr in tightly sealed tubes maintained horizontally at either 0 C, 20 C, or 37 C, before they were injected into jirds. Necropsies were performed on the jirds 120-130 days after injection to recover and count adult worms. Levels of microfilaremia were also determined. We found that L3s held overnight at 0 C, although apparently viable, were unable to survive in jirds. However, larvae kept at 20 C and 37 C produced patent infections with adult worms in normal locations even after 120 hr of in vitro cultivation. There was no statistical difference in mean worm recovery or size of worms from jirds infected with freshly harvested L3s and jirds injected with larvae that were maintained overnight at 20 C or 37 C. When cultured L3s were shipped from Michigan to Connecticut by overnight air courier, along with infected living mosquitos, the L3s appeared to be 99% viable upon arrival. L3s shipped in F-12 produced patent infections in C.B.-17 scid/scid mice with worm recoveries comparable to those observed in mice injected with L3s freshly obtained from shipped mosquitos.
感染期丝虫幼虫（L3）的运输通常是通过运送活的感染媒介或液氮冷冻保存的L3来完成的。我们的目标是找到运输L3的培养条件，既能促进马来布鲁线虫幼虫的存活，又不改变其感染易感动物的能力。在初步研究中，我们观察到含有抗生素和1%胎牛血清的Ham氏营养混合液F-12能够支持L3至少10天而无明显发育。为了评估培养温度对感染性的影响，将新鲜的L3分成几组，一组立即注射到沙鼠体内（感染性对照），其余组在水平放置的密封管中于0℃、20℃或37℃下孵育24、48或120小时，然后再注射到沙鼠体内。在注射后120 - 130天对沙鼠进行剖检，以回收并计数成虫。还测定了微丝蚴血症水平。我们发现，在0℃下保存过夜的L3虽然看起来存活，但无法在沙鼠体内存活。然而，即使在体外培养120小时后，保存在20℃和37℃的幼虫在正常部位仍产生了有虫感染。从刚收获的L3感染的沙鼠以及注射了在20℃或37℃下保存过夜的幼虫的沙鼠中回收的平均虫数或虫体大小没有统计学差异。当通过隔夜航空快递将培养的L3从密歇根州运送到康涅狄格州时，与感染的活蚊子一起运输，L3到达时似乎有99%的存活率。用F-12运输的L3在C.B.-17 scid/scid小鼠中产生了有虫感染，虫体回收率与注射从运输的蚊子中新鲜获得的L3的小鼠中观察到的回收率相当。
