Mellor P S
AFRC Institute for Animal Health, Pirbright Laboratory, Nr. Woking, Surrey, UK.
Curr Top Microbiol Immunol. 1990;162:143-61. doi: 10.1007/978-3-642-75247-6_6.
BTV is maintained in nature by an endless series of alternating cycles of replication in Culicoides midges and various mammalian ruminant species. Experimentation has shown that the ability of the virus to infect Culicoides persistently and be transmitted by them is restricted to a relatively small number of species. In essence, therefore, the world distribution map of BTV is little more than a distribution map of competent insect vectors. Once ingested by a competent vector, BTV attaches to the luminal surface of the mid-gut cells, infects these cells and replicates in them. Progeny virus is then released through the basement lamina into the haemocoel from where the secondary target organs including the salivary glands are infected. Subsequent to virus replication in the salivary glands transmission can taken place. The whole cycle from infection to transmission takes between 10-15 days at 25 degrees C and individual vectors once infected usually remain so for life. Not all female midges within a vector species are susceptible to infection with BTV, or if infected, are competent to transmit the virus. A series of barriers or constraints exists within certain individuals of a vector species which either prevents virus infection or else restricts it in such a way as to stop transmission. Each population of a vector species of Culicoides has a variable proportion of these so-called refractory midges. The refractory and susceptible traits for BTV within a vector species are under genetic control, and by selective breeding, highly susceptible or completely insusceptible populations can be obtained. However, the mechanisms by which these traits are expressed are poorly understood. Further studies are therefore urgently required to determine the precise biochemical nature of these mechanisms and their mode of operation.
蓝舌病病毒（BTV）在自然界中通过在库蠓和各种反刍动物之间不断交替的复制循环得以维持。实验表明，该病毒持续感染库蠓并由其传播的能力仅限于相对少数的物种。因此，从本质上讲，BTV的全球分布图实际上就是其有效昆虫媒介的分布图。一旦被有效的媒介摄取，BTV就会附着在中肠细胞的腔表面，感染这些细胞并在其中复制。子代病毒随后通过基膜释放到血腔中，从那里感染包括唾液腺在内的次级靶器官。在唾液腺中进行病毒复制后即可发生传播。在25摄氏度下，从感染到传播的整个周期需要10至15天，而且单个媒介一旦被感染，通常终身携带病毒。并非媒介物种中的所有雌性库蠓都易感染BTV，或者即使被感染，也不一定能够传播病毒。在媒介物种的某些个体中存在一系列障碍或限制因素，这些因素要么阻止病毒感染，要么以阻止传播的方式限制病毒感染。库蠓媒介物种的每个种群中都有不同比例的这些所谓的抗性库蠓。媒介物种中对BTV的抗性和易感性特征受遗传控制，通过选择性育种，可以获得高度易感或完全不易感的种群。然而，这些特征的表达机制尚不清楚。因此，迫切需要进一步研究以确定这些机制的确切生化性质及其运作方式。
