Spikes made of the glycoprotein hemagglutinin, or H spikes, enable viruses to latch onto their host cells, while N spikes, those made of the glycoprotein neuraminidase, enable viruses to escape their host cells upon reaching maturity, explains Midlands Technical College. These spikes are found on enveloped viruses.
One virus that possesses both H spikes and N spikes is the influenza virus, which exists in Type A, B and C forms based on the different protein and nucleic acid makeup of the virus, notes the National Institute of Allergy and Infectious Diseases. Influenza Type A has been responsible for several global outbreaks of the flu throughout history, and Type A viruses can contain 16 subtypes of H spikes and nine N-spike subtypes. The name of an influenza strain indicates which spike subtypes it contains. Thus, the H1N1 virus responsible for the swine flu contains subtype one H spikes and subtype one N spikes.
The envelope found on a spiked virus originates from its host cell's plasma membrane, notes the National Cancer Institute. Via a process biologists call "budding off," a new virus particle breaks free from the inside of the host cell with the help of the N spikes of mature viruses, explains JRank's science encyclopedia. While it escapes the host cell, it becomes wrapped up in part of the cell's membrane.