Infected tick salivary gland. Confocal light micrograph of a cross-section of a tick salivary gland infected with Langat virus (green), a flavivirus with a positive-sense RNA (ribonucleic acid) genome. The two rounded structures on the right, acini, are shown attached to a duct (yellow). The lower acinus is infected, as shown by the green fluorescent signal. US National Institutes of Health (NIH) scientists are exploring black-legged tick (Ixodes scapularis) salivary glands as a tool for studying flavivirus transmission and infection.