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A biphasic epigenetic switch controls immunoevasion, virulence and niche adaptation in non-typeable Haemophilus influenzae.

Atack JM, Srikhanta YN, Fox KL, Jurcisek JA, Brockman KL, Clark TA, Boitano M, Power PM, Jen FE, McEwan AG, Grimmond SM, Smith AL, Barenkamp SJ, Korlach J, Bakaletz LO, Jennings MP - Nat Commun (2015)

Bottom Line: Here, we use single molecule, real-time (SMRT) methylome analysis to identify the DNA-recognition motifs for all five of these modA alleles.Phase variation of these alleles regulates multiple proteins including vaccine candidates, and key virulence phenotypes such as antibiotic resistance (modA2, modA5, modA10), biofilm formation (modA2) and immunoevasion (modA4).Our results indicate that a biphasic epigenetic switch can control bacterial virulence, immunoevasion and niche adaptation in an animal model system.

View Article: PubMed Central - PubMed

Affiliation: Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia.

ABSTRACT
Non-typeable Haemophilus influenzae contains an N(6)-adenine DNA-methyltransferase (ModA) that is subject to phase-variable expression (random ON/OFF switching). Five modA alleles, modA2, modA4, modA5, modA9 and modA10, account for over two-thirds of clinical otitis media isolates surveyed. Here, we use single molecule, real-time (SMRT) methylome analysis to identify the DNA-recognition motifs for all five of these modA alleles. Phase variation of these alleles regulates multiple proteins including vaccine candidates, and key virulence phenotypes such as antibiotic resistance (modA2, modA5, modA10), biofilm formation (modA2) and immunoevasion (modA4). Analyses of a modA2 strain in the chinchilla model of otitis media show a clear selection for ON switching of modA2 in the middle ear. Our results indicate that a biphasic epigenetic switch can control bacterial virulence, immunoevasion and niche adaptation in an animal model system.

No MeSH data available.


Related in: MedlinePlus

Opsonophagocytic killing curves using strain C486 modA4 ON/OFF strain pair.Assays were carried out using guinea pig antiserum raised against purified HMW proteins from NTHi strain 12, with NTHi strain C486 harbouring the modA4 ON/OFF pair. Three independent assays were carried out per strain, with error bars representing one s.d. Statistical significance was calculated using Student's t-test, and was <0.05 at all dilutions of antiserum. Individual P values—1:10=0.034; 1:20=0.0185; 1:40=0.0012; 1:80=0.009; 1:160=0.0065.
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f4: Opsonophagocytic killing curves using strain C486 modA4 ON/OFF strain pair.Assays were carried out using guinea pig antiserum raised against purified HMW proteins from NTHi strain 12, with NTHi strain C486 harbouring the modA4 ON/OFF pair. Three independent assays were carried out per strain, with error bars representing one s.d. Statistical significance was calculated using Student's t-test, and was <0.05 at all dilutions of antiserum. Individual P values—1:10=0.034; 1:20=0.0185; 1:40=0.0012; 1:80=0.009; 1:160=0.0065.

Mentions: Differential expression of HMW protein had been observed in strain C486, containing the modA4 phasevarion. Antiserum was available that would recognize the HMW protein in this strain. We tested our C486 modA4 ON/OFF strain pair in an opsonophagocytic killing assay42. The modA4ON strain was significantly (P<0.05 at all the data points; calculated using Student's t-test) more susceptible to killing at every dilution of antibody tested compared with modA4OFF (Fig. 4). No killing was observed with this strain pair using pre-immune sera from animals used to raise anti-HMW sera, nor was killing observed with antisera raised against the protein Hia (data not shown).


A biphasic epigenetic switch controls immunoevasion, virulence and niche adaptation in non-typeable Haemophilus influenzae.

Atack JM, Srikhanta YN, Fox KL, Jurcisek JA, Brockman KL, Clark TA, Boitano M, Power PM, Jen FE, McEwan AG, Grimmond SM, Smith AL, Barenkamp SJ, Korlach J, Bakaletz LO, Jennings MP - Nat Commun (2015)

Opsonophagocytic killing curves using strain C486 modA4 ON/OFF strain pair.Assays were carried out using guinea pig antiserum raised against purified HMW proteins from NTHi strain 12, with NTHi strain C486 harbouring the modA4 ON/OFF pair. Three independent assays were carried out per strain, with error bars representing one s.d. Statistical significance was calculated using Student's t-test, and was <0.05 at all dilutions of antiserum. Individual P values—1:10=0.034; 1:20=0.0185; 1:40=0.0012; 1:80=0.009; 1:160=0.0065.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4525171&req=5

f4: Opsonophagocytic killing curves using strain C486 modA4 ON/OFF strain pair.Assays were carried out using guinea pig antiserum raised against purified HMW proteins from NTHi strain 12, with NTHi strain C486 harbouring the modA4 ON/OFF pair. Three independent assays were carried out per strain, with error bars representing one s.d. Statistical significance was calculated using Student's t-test, and was <0.05 at all dilutions of antiserum. Individual P values—1:10=0.034; 1:20=0.0185; 1:40=0.0012; 1:80=0.009; 1:160=0.0065.
Mentions: Differential expression of HMW protein had been observed in strain C486, containing the modA4 phasevarion. Antiserum was available that would recognize the HMW protein in this strain. We tested our C486 modA4 ON/OFF strain pair in an opsonophagocytic killing assay42. The modA4ON strain was significantly (P<0.05 at all the data points; calculated using Student's t-test) more susceptible to killing at every dilution of antibody tested compared with modA4OFF (Fig. 4). No killing was observed with this strain pair using pre-immune sera from animals used to raise anti-HMW sera, nor was killing observed with antisera raised against the protein Hia (data not shown).

Bottom Line: Here, we use single molecule, real-time (SMRT) methylome analysis to identify the DNA-recognition motifs for all five of these modA alleles.Phase variation of these alleles regulates multiple proteins including vaccine candidates, and key virulence phenotypes such as antibiotic resistance (modA2, modA5, modA10), biofilm formation (modA2) and immunoevasion (modA4).Our results indicate that a biphasic epigenetic switch can control bacterial virulence, immunoevasion and niche adaptation in an animal model system.

View Article: PubMed Central - PubMed

Affiliation: Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia.

ABSTRACT
Non-typeable Haemophilus influenzae contains an N(6)-adenine DNA-methyltransferase (ModA) that is subject to phase-variable expression (random ON/OFF switching). Five modA alleles, modA2, modA4, modA5, modA9 and modA10, account for over two-thirds of clinical otitis media isolates surveyed. Here, we use single molecule, real-time (SMRT) methylome analysis to identify the DNA-recognition motifs for all five of these modA alleles. Phase variation of these alleles regulates multiple proteins including vaccine candidates, and key virulence phenotypes such as antibiotic resistance (modA2, modA5, modA10), biofilm formation (modA2) and immunoevasion (modA4). Analyses of a modA2 strain in the chinchilla model of otitis media show a clear selection for ON switching of modA2 in the middle ear. Our results indicate that a biphasic epigenetic switch can control bacterial virulence, immunoevasion and niche adaptation in an animal model system.

No MeSH data available.


Related in: MedlinePlus