id	author	title	date	pages	extension	mime	words	sentences	flesch	summary	cache	txt
cord-255857-y9wjp0aj	Yuan, Shishan	Erratum to “Complete genome comparison of porcine reproductive and respiratory syndrome virus parental and attenuated strains”	2001-11-05		.txt	text/plain	4283	235	56	Two full-length porcine reproductive and respiratory syndrome virus (PRRSV) genomes, strain VR-2332 and its cell culture passaged descendent RespPRRS vaccine strain, were compared and analyzed in order to identify possible sites of attenuation. However, the cluster of amino acid mutations located near the carboxyl terminal end suggests that the replicase region was altered during passage to result in a more fit virus for replication in cell culture, as evidenced by the in vitro one-step growth curve comparison shown in Fig. 4 . Sequence analysis of strains VR-2332 and RespPRRS indicated that there were 15 nucleotide changes in this region, and all but one of which resulted in amino acid alterations. Attenuation can result from changes in many areas of viral genomes and the 41 nucleotide mutations described include alterations in several key PRRSV regions.	./cache/cord-255857-y9wjp0aj.txt	./txt/cord-255857-y9wjp0aj.txt