Effect of mesoporous silica under Neisseria meningitidis transformation process: environmental effects under meningococci transformation

Abstract

Background: This study aimed the use of mesoporous silica under the naturally transformable Neisseria meningitidis, an important pathogen implicated in the genetic horizontal transfer of DNA causing a escape of the principal vaccination measures worldwide by the capsular switching process. This study verified the effects of mesoporous silica under N. meningitidis transformation specifically under the capsular replacement.

Methods: we used three different mesoporous silica particles to verify their action in N. meningitis transformation frequency.

Results: we verified the increase in the capsular gene replacement of this bacterium with the three mesoporous silica nanoparticles.

Conclusion: the mesouporous silica particles were capable of increasing the capsule replacement frequency in N. meningitidis.

Figure 1

(a) SEM image of SBA-15 which evidence the presence of elongated, vermicular shaped particles 590 nm wide. TEM image of SBA-15, which shows a well-defined hexagonal arrangement of uniform pores when (b) the incident electron beam was parallel to the main axis of the mesopores and unidirectional channels, and (c) the electron beam was perpendicular to the channel axis.

Figure 2

(a) SEM image of SBA-16 exhibits rounded shape with diameter size between 15 and 20 μm and of an "aggregated morphology". TEM images of SBA-16 showed well ordered cubic mesoporous which confirmed the 3D cubic pore structure, when (b) viewed along the pore axis and (c) perpendicularly to the pore axis.

Figure 3

Schematic representation of the capsule genes of C serogroup in disrupted construction of NMB0065 gene with aaDA cassette. The NMB0065 gene was amplified using the 03-12-3 and 03-12-4 oligonucleotides (Table 3) from C2135 strain. This fragment was cloned into the pGEM-T Easy Vector System II (Promega Corporation, Madison, WI, USA), to generate the plasmid pLAN6. E. coli strain Z501 was transformed with plasmid pLAN6 resulting in the plasmid pLAN7. The ΩaaDA cassette was inserted into the BclI site of pLAN7 to generate plasmid pLAN45, which was transformed into the C2135 strain to generate the isogenic mutant strain M2.

Figure 4

Schematic representation of the capsule genes of W135 serogroup in transcriptional fusion of synG with ermAM cassette. The synG gene responsible for the synthesis of the W135 capsule was amplified using the 98-30 and 03-12-5 oligonucleotides (Table 3) from W135_ATCC strain. The amplified fragment was cloned into the pGEM-T Easy Vector System I (Promega, Madison, WI, USA), to generate the plasmid pLAN11. In the same conditions, another fragment was amplified using the 04.02-2/galECK29A from synG downstream sequence to generate pLAN52. The ermAM cassette was insered into NcoI site of pLAN52 to generate pLAN53. The fragment amplified from pLAN53 with the ERAM1 and galECK29A (Dolan Livengood [23] et al., 2003) was insered into PstI site of pLAN11 to generate pLAN13-2. This plasmid was linearised by the enzyme SphI and transformed into W135_ATCC strain to generate the synG::ermAM strain M6, erythromycin resistant.

Figure 5

Graphic of the transformation ratio obtained with In A: ratio of transformation of C2135 strain with donor DNA from M2 mutant (ΔNMB0065:: ΩaaDA), In B: ratio of transformation of C2135 strain with donor DNA from M6 mutant (synG:: ermAM), mimicking a capsular switch replacement, significant analysis of both tests were performed by Tukey test comparing separately each treatment SBA-15, SBA-16 and SBA-15/P(N-iPAAm) with the control without nanoparticles (w/o).