【正文】 equences of 67 PRRSVs: 35 HPPRRSVs (HuN4 and LNSY081 isolated in our laboratory and 33 viruses isolated in other laboratories), 28 classic PRRSVs (18 viruses isolated from China and 10 viruses representing other Asian countries and North America), and 4 mercially available attenuated live PRRSV vaccine viruses. Except for the 2 viruses we isolated (HuN4 and LNSY081), the fulllength sequences of the other 65 viruses were obtained from and deduced amino acid sequences of these PRRSVs were aligned and pared by using previous methods . Whole genomebased phylogeic analysis showed that these 67 PRRSVs could be divided into 4 subgroups . Ten classic PRRSVs from China, together with the North American prototype virus VR2332 and the vaccine virus RespPRRS/Repromodified live vaccine, were classified into subgroup 1. The first Chinese isolate, CH1a, and its 3 derivatives (CH2021, CH2021, and CH2021) were classifi ed into subgroup 2. All 35 HPPRRSVs were classified into subgroup 4, and they shared high homology (99%) in their genomic sequences. The other 4 Chinese PRRSVs, including HB1(sh)/2021,HB2(sh)/2021, Em2021, and SHB,belonged to subgroup 3, an intermediate subgroup between subgroups 2and 4. Phylogeically, HPPRRSVs had a close relationship with subgroups 2 and 3. Four conserved deletions were shown among all HPPRRSVs, including an adenosine deletion at position 122 in the 5′untranslated region, a guanosine deletion at position 15,278 in the 3′untranslated region, and 2 discontinuous deletions in the NSP2, including a single amino acid