129
Diagnosis
A LAMP assay was developed, involving four primers designed from the 16S-23S
rRNA ISR of Noc. salmonicida . The LAMP products were determined by gel electrophoresis, and also visually after addition of the nucleic acid stain SYBR Green
I. The sensitivity was reported as 1.68 × 10
3 CFU/ml (i.e. 16.8 CFU/reaction), which
was regarded as 10-hold higher than conventional PCRs. The LAMP detected the
pathogen in diseased fi sh tissues (Xia et al. 2015 ).
Nocardia seriolae
Characteristics of the Pathogen
A good description exists for Noc. kampachi (Kariya et al. 1968 ; Kubota et al. 1968 ;
Kusuda et al. 1974 ). However, in retrospect it would appear that Kariya and coworkers exercised considerable taxonomic intuition in elevating the isolates into a
new species, i.e. Noc. kampachi . Unfortunately, the results of G + C determinations
were not reported. Moreover, it is perhaps surprising that the original authors did
not provide detailed reasons explaining why Noc. kampachi should be regarded as
distinct from other species of Nocardia. This is especially relevant as there is some
resemblance between the descriptions of Noc. kampachi and Noc. caviae (Table 3.2 ).
Nevertheless, a more recent publication has formally proposed another nomenspecies, i.e. Noc. seriolae, which effectively replaces Noc. kampachi (Kudo et al. 1988 ).
Excellent descriptions of fi sh pathogenic isolates have now been provided, with
Japanese isolates displaying 99.9 % sequence homology with the type strain
(Shimahara et al. 2008 ).
A proposal has been made to divide Taiwanese isolates into two groups based
around the reaction to α-glucosidase (Shimahara et al. 2009 ).
Box 3.18: Nocardia seriolae
The isolates of Noc. seriolae contain meso- diaminopimelic acid, arabinose
and galactose, suggesting chemotype IVA. The major components of the cellular fatty acids are n- C 16:0 , n -C 16:1 and n- C 18:1 ; 10-methyl-C 19:0 is also present
as a major component in four of the fi ve isolates examined. Iso- and anteisobranched acids have not been detected. The total number of carbon atoms in
the mycolic acids is from 44 to 58. The predominant isoprenoid quinone is
tetrahydrogenated menaquinone with 8 isoprene units. The G + C ratio of the
DNA is 66.8–67.4 moles %.
Nocardiaceae Representatives
Diagnosis
A LAMP assay was developed, involving four primers designed from the 16S-23S
rRNA ISR of Noc. salmonicida . The LAMP products were determined by gel electrophoresis, and also visually after addition of the nucleic acid stain SYBR Green
I. The sensitivity was reported as 1.68 × 10
3 CFU/ml (i.e. 16.8 CFU/reaction), which
was regarded as 10-hold higher than conventional PCRs. The LAMP detected the
pathogen in diseased fi sh tissues (Xia et al. 2015 ).
Nocardia seriolae
Characteristics of the Pathogen
A good description exists for Noc. kampachi (Kariya et al. 1968 ; Kubota et al. 1968 ;
Kusuda et al. 1974 ). However, in retrospect it would appear that Kariya and coworkers exercised considerable taxonomic intuition in elevating the isolates into a
new species, i.e. Noc. kampachi . Unfortunately, the results of G + C determinations
were not reported. Moreover, it is perhaps surprising that the original authors did
not provide detailed reasons explaining why Noc. kampachi should be regarded as
distinct from other species of Nocardia. This is especially relevant as there is some
resemblance between the descriptions of Noc. kampachi and Noc. caviae (Table 3.2 ).
Nevertheless, a more recent publication has formally proposed another nomenspecies, i.e. Noc. seriolae, which effectively replaces Noc. kampachi (Kudo et al. 1988 ).
Excellent descriptions of fi sh pathogenic isolates have now been provided, with
Japanese isolates displaying 99.9 % sequence homology with the type strain
(Shimahara et al. 2008 ).
A proposal has been made to divide Taiwanese isolates into two groups based
around the reaction to α-glucosidase (Shimahara et al. 2009 ).
Box 3.18: Nocardia seriolae
The isolates of Noc. seriolae contain meso- diaminopimelic acid, arabinose
and galactose, suggesting chemotype IVA. The major components of the cellular fatty acids are n- C 16:0 , n -C 16:1 and n- C 18:1 ; 10-methyl-C 19:0 is also present
as a major component in four of the fi ve isolates examined. Iso- and anteisobranched acids have not been detected. The total number of carbon atoms in
the mycolic acids is from 44 to 58. The predominant isoprenoid quinone is
tetrahydrogenated menaquinone with 8 isoprene units. The G + C ratio of the
DNA is 66.8–67.4 moles %.
Nocardiaceae Representatives