1. Division of Retrovirology, NIBSC/HPA, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QJ, United Kingdom
2. Laboratory Branch, Division of HIV/AIDS Prevention, National Center for HIV, STD, TB Prevention, CCID, Centers for Disease Control and Prevention, Atlanta, Georgia
3. SIIDC, Solna, Stockholm, Sweden
4. BPRC, Rijswijk, Holland
5. Division of Experimental Retrovirology and Non-Human Primate Models, AIDS National Centre, Instituto Superiore Sanità, Rome, Italy