question: How Flaviviridae family of viruses infects vertebrates?
answer: A wide range of about 500 different viruses is transmitted by arthropods such as ticks, mosquitoes and sandflies. These arboviruses multiply in the arthropod vector, and for each virus there is a natural cycle involving vertebrates (various birds or mammals) and arthropods. The virus enters the arthropod when the latter takes a blood meal from the infected vertebrate, and passes through the gut wall to reach the salivary gland where replication takes place. Once this has occurred, 1–2 weeks after ingesting the virus, the arthropod becomes infectious, and can transmit the virus to another vertebrate during a blood meal. Certain arboviruses that infect ticks are also transmitted directly from adult tick to egg (transovarial transmission), so that future generations of ticks are infected without the need for a vertebrate host.