Listeria monocytogenes serovar 4a is a possible evolutionary intermediate between L. monocytogenes serovars 1/2a and 4b and L. innocua.
The genus Listeria consists of six closely related species and forms three phylogenetic groups: L. monocytogenes- L. innocua, L. ivanovii-L. seeligeri-L. welshimeri, and L. grayi. In this report, we attempted to examine the evolutionary relationship in the L. monocytogenes-L. innocua group by probing the nucleotide sequences of 23S rRNA and 16S rRNA, and the gene clusters lmo0029-lmo0042, ascBdapE, rplS-infC, and prs-ldh in L. monocytogenes serovars 1/2a, 4a, and 4b, and L. innocua. Additionally, we assessed the status of L. monocytogenes-specific inlA and inlB genes and 10 L. innocua-specific genes in these species/serovars, together with phenotypic characterization by using in vivo and in vitro procedures. The results indicate that L. monocytogenes serovar 4a strains are genetically similar to L. innocua in the lmo0035-lmo0042, ascB-dapE, and rplS-infC regions and also possess L. innocua-specific genes lin0372 and lin1073. Furthermore, both L. monocytogenes serovar 4a and L. innocua exhibit impaired intercellular spread ability and negligible pathogenicity in mouse model. On the other hand, despite resembling L. monocytogenes serovars 1/2a and 4b in having a nearly identical virulence gene cluster, and inlA and inlB genes, these serovar 4a strains differ from serovars 1/2a and 4b by harboring notably altered actA and plcB genes, displaying strong phospholipase activity and subdued in vivo and in vitro virulence. Thus, by possessing many genes common to L. monocytogenes serovars 1/2a and 4b, and sharing many similar gene deletions with L. innocua, L. monocytogenes serovar 4a represents a possible evolutionary intermediate between L. monocytogenes serovars 1/2a and 4b and L. innocua.
Zhejiang University Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory of Prevent Veterinary Medicine, Hangzhou, China.
Jianshun
J
Chen
Lingli
L
Jiang
Xueyan
X
Chen
Xiaokai
X
Luo
Yang
Y
Chen
Ying
Y
Yu
Guoming
G
Tian
Dongyou
D
Liu
Weihuan
W
Fang
D000818:Animals; D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics; D001483:Base Sequence; D005075:Biological Evolution; D015941:Complement Hemolytic Activity Assay; D004269:DNA, Bacterial / Q000302:isolation & purification; D014644:Genetic Variation; D008087:Listeria / Q000145:classification* / Q000472:pathogenicity / Q000502:physiology; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000032:analysis / Q000235:genetics; D012338:RNA, Ribosomal, 23S / Q000032:analysis / Q000235:genetics; D017422:Sequence Analysis, DNA; D012756:Sheep; D010738:Type C Phospholipases / Q000378:metabolism; D014774:Virulence; D037521:Virulence Factors / Q000032:analysis / Q000235:genetics
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D008565:Membrane Proteins; D012336:RNA, Ribosomal, 16S; D012338:RNA, Ribosomal, 23S; D037521:Virulence Factors; C072980:actA protein, Listeria monocytogenes; D010738:Type C Phospholipases