[1] McGill Univ, Dept Microbiol & Immunol, 3775 Univ St, Montreal, PQ H3A 2B4, Canada
[2] Univ Geneva, Med Sch, Dept Microbiol & Mol Med, 1 Rue Michel Servet, CH-1211 Geneva 4, Switzerland
[3] Univ Ottawa, Dept Cellular & Mol Med, 451 Smyth Rd, Ottawa, ON K1H 8L1, Canada