Gallid alphaherpesvirus 1 (GaHV-1) (also known as Avian herpesvirus 1) is a virus of the family Herpesviridae that causes avian infectious laryngotracheitis.

The disease is usually referred to as Infectious laryngotracheitis or simply LT in the poultry industry. It is widely viewed as one of the most contagious viruses that affect the poultry industry. A confirmed case will usually result in the establishment of a quarantine zone around the farm. Inside this quarantine zone, poultry workers will avoid poultry farms to prevent the spread of the virus.

GaHV-1 is shed in respiratory secretions and transmitted by droplet inhalation or via fomites. A previously unexposed flock will develop cases for two to eight weeks following introduction. The incubation period is two to eight days.