The neucleocapsid is assembled in the nucleus but the envelope for complete assembly is from the host's plasma membrane. There are three distinct influenza viruses, A, B, and C. Types B and C are found in humans only, while type A is found in horse, swine, birds and humans, and cause most pandemics. The three major types are differentiated based on the antigenic differences of their glycoprotein and M protein. Specificity of strains within the types are based on their spikes. Because the 8 RNA segments can be rearranged the virus can evade previous immunity via changes in composition of the H and N spikes.
Influenza is a disease of the upper respiratory tract.
Symptoms - Fever, cough, headache, muscular aches and sore throats. The disease is self limiting. Treatment - Ammantadine and rimantadine. One is hemagglutin for adsorption to the cell surface, and the other an F glycoprotein for fusion, hemolysis and entering the host cell. There are no neuraminidase spikes.