Bactericidal killing of meningococcal W strains isolated in Argentina by the sera of adolescents and infants immunized with 4-component meningococcal serogroup B vaccine (4CMenB)

Figures & data

Figure 1. Characteristics of the 11 hSBA-tested MenW strains from 2010–2011; all 22 strains from 2010–2011; and the 41 strains from 2018–2021.

Abbreviations: 0, not present; CC, clonal complex; fHbp, factor H binding protein; hSBA, human serum bactericidal assays; MenW, meningococcal serogroup W; n, number; NadA, Neisseria adhesin A; ND, not determined; NHBA, Neisserial Heparin Binding Antigen; porA, porin A; ST, sequence type; VR, variable region.

Figure 2. Characteristics of the 11 hSBA-tested MenW strains from 2010–2011.

Abbreviations: 0, not present; CC, clonal complex; fHbp, factor H binding protein; hSBA, human serum bactericidal assays; MenW, meningococcal serogroup W; NadA, Neisseria adhesin A; ND, not determined; NHBA, Neisserial Heparin Binding Antigen; porA, porin A; ST, sequence type.

Table 1. Bactericidal titers by vaccination status.

MenW isolate	MenACWY vaccine		4CMenB vaccine
	Adolescents		Adolescents		Infants
	Pre-immune	Post-immune	Pre-immune	Post-2nd dose	Control sera	Post-4th dose
ARG-2991	<16	256	<4	<4	<2	<2
ARG-3006	<16	>512	<4	>128*	<2	>64
ARG-3052	<16	256	<4	>128	2	>64†
ARG-3064	<16	256	<4	>128	<2	>64
ARG-3158	<16	>512	<4	64*	<2	>64
ARG-3200	<16	256	<4	>128	<2	>64
ARG-3216	<16	256	<4	>128	<2	>64*
ARG-3223	<16	256	4	>128	2	>64
ARG-3273	<16	>512	<4	>128*	<2	>64*
ARG-3279	<16	≥512	<4	64	<2	>64
ARG-3320	<16	≥512	<4	>128*	<2	>64

*Prozone effect: bacterial survival was observed at high antibody concentrations due to the prozone effect, which is often detected when there is an excess of antibodies.

^†Bacteriostatic.

4CMenB, 4-component meningococcal serogroup B vaccine; ARG, Argentina; MenACWY, meningococcal serogroups A, C, W, and Y; MenW, meningococcal serogroup W.

Table 2. Bactericidal titers using untreated and 4CMenB antibody-depleted sera.

MenW isolate	4CMenB vaccine
	Adolescents		Infants
	Untreated	Depleted*	Untreated	Depleted*
ARG-3006	>128^†	<4	>64	<8
ARG-3064	>128^†	<4	>64	<8
ARG-3216	>128	<8	>128	<16
ARG-3273	>128^†	<8	>128	<16

*Preincubated with 500 µg/mL 4CMenB.

^†Prozone effect: bacterial survival was observed at high antibody concentrations due to the prozone effect, which is often detected when there is an excess of antibodies.

4CMenB, 4-component meningococcal serogroup B vaccine; ARG, Argentina; MenW, meningococcal serogroup W.