Para pt-pt, parece-me ser isto.

What means "seed virus"?
A "Seed Virus" is the culture of virus used to start a culture. Seed means to inoculate. And a "Seed" culture is the first culture used to start stock cultures.
So if you were going to start a stock culture of virus for vaccine development, you would first inoculate your culture with a seed virus.
http://www.scientistsolutions.com/t5662-what means _seed vir...

Dada a limitada disponibilidade∗ do Inóculo Viral Original (MSV - Master Seed Virus) e do Inóculo Celular Principal (MCS - Master Cell Seed), foram apenas re-ensaiados o Inóculo Viral de Trabalho (WSV - Working Seed Virus) e o Inóculo Celular de Trabalho (WCS - Working Cell Seed) de Bayovac IBR Viva Marcada e de Rhinobovin Viva Marcada para comprovação da ausência de vírus BVD, utilizando os métodos IPLA e PCR.

http://ec.europa.eu/health/documents/community-register/2000...