Comparison of L-SBA and conventional SBA assay with standard reference sera against <i>Shigella flexneri</i> serogroups 2a and 3a.

<p>HI standard reference serum against <i>S</i>. <i>flexneri</i> 2a (A and B) and <i>S</i>. <i>flexneri</i> 3a (C and D) was tested by L-SBA (A and C, respectively) and by the conventional assay (B and D, respectively) in three independent experiments. Black lines represent the curve fitting by nonlinear regression for each replicate.</p

Immune states.

<p>The immune states and their transitions for infection and vaccine induced immunity. For individuals in the non-immune categories the time in this category depends on the infection rates and vaccination strategies. For other immune states, time in the state before losing immunity is sampled from a defined distribution, modulated by exposure/vaccination history. Where there are multiple possible transitions out of a state, conditional probabilities determine which path an individual follows. The order in which the probabilities are applied is specified in the text. <i>P₆</i>, <i>P₇</i>, <i>P₈</i> refer to subclinical infections, <i>P₉</i>, <i>P₁₀</i> to clinical infections. <i>P₁₁, P₁₂</i> probabilities of inducing immunity in non-vaccinated individuals, <i>P₁₃, P₁₄, P₁₅</i> in previously vaccinated individuals.</p

Impact of carriers and <i>R_c</i> on the stability of time series of typhoid cases in an endemic community: individual simulations.

<p>Individual simulations are shown of the number of cases per month for a 240 month (20 year) simulation period. Simulations used the basic Dhaka parameters but varied <i>R_c</i> (1.5: top panel, 3.3: middle panel and 10 lower panel) assuming a zero probability of becoming a carrier (red plot), 12.5% of standard probability of becoming a carrier (blue plot) and the standard probability (green plot). At low transmission (<i>R_c</i> 1.5) in the absence of carriers, the infection becomes epidemic and does not persist, hence only low and standard probability traces are present in the top panel. The 95% confidence limits on the maximum and minimum cases per month are shown by the thin red, blue or green lines for the corresponding probabilities of becoming a carrier derived from 200 simulations. The lower 95% confidence is zero for zero probability of carriage at an <i>R_c</i> of 3.3 and zero for 12.5% probability for and <i>R_c</i> of both 1.5 and 3.3 and are not shown on these graphs. In each simulation the starting population was approximately 10,000 growing to 16,000 after 20 years.</p

Development of a high-throughput method to evaluate serum bactericidal activity using bacterial ATP measurement as survival readout - Fig 4

<p><b>Correlation of serum titers from individual mouse sera against <i>S</i>. Typhimurium (A) and <i>S</i>. Enteritidis (B) as determined by L-SBA and by the conventional SBA assay.</b> Individual mouse sera were simultaneously assayed by L-SBA (y-axis) and by the conventional CFU-based assay (x-axis) against <i>S</i>. Typhimurium (A) and against <i>S</i>. Enteritidis (B). Plots compare titers from each assay and demonstrate a linear correlation with a slope of 1. Black lines represent the fitting by linear regression. SBA titers were obtained by single experiments.</p

Bacterial strains used in this study.

<p>Bacterial strains used in this study.</p

Effect of varying <i>R_c</i> and the proportion of infections giving clinical cases.

<p>The simulations systematically <i>R_c</i> for probabilities of 0.02 (short dash), 0.1 (standard conditions – thick continuous line) and 0.5 (long dash) of an infection in a non-immune person with the standard Dhaka parameter set for other parameters, showing the average age of infection, the force of infection (infectious dose per person per month), the number of chronic carriers per 100,000 and the number of subclinical and clinical cases per 100,000 per year.</p

Optimization of bacterial cell concentration for L-SBA.

<p>(A) Different bacterial concentrations were tested with 5% BRS and measured by luminescence at T0 (triangle symbol) and at T180 (square symbol). (B) Bacterial cells at 1.5 x 10⁵ CFU/mL were diluted down until 1.0 x 10³ CFU/mL and measured by luminescence. The area within the dashed lines define the confidence interval of the best-fit line of the linear regression (y = 0.009465x + 10.28). CPS, counts per second.</p

Comparison of L-SBA and conventional assay using pooled mouse sera against <i>Neisseria meningitidis</i> serogroups A and W.

<p>HI pooled mouse sera were tested by L-SBA (A, C) or by conventional assay (B, D) against <i>N</i>. <i>meningitidis</i> A Niga 16/09 strain (A, B) or <i>N</i>. <i>meningitidis</i> W Mali 4/11 strain (C, D). Results are the mean ± standard deviation values from three replicates (for some points the error bars are not visible because shorter than the symbols).</p

Comparison of titers obtained by the conventional SBA assay and by L-SBA, using a panel of standard reference sera or mAbs against different bacterial species.

<p>White or grey bars represent the SBA titers calculated from the conventional CFU-counts or from L-SBA, respectively. Standard reference sera were used against <i>C</i>. <i>freundii</i>, <i>S</i>. Typhimurium, <i>S</i>. Enteritidis, <i>S</i>. <i>flexneri 2a and 3a</i> and <i>S</i>. <i>sonnei</i>. For <i>N</i>. <i>meningitidis</i> A and W anti-capsular mAbs were used. The results are the mean ± standard deviation values from three independent experiments.</p

Impact of carriers and <i>R_c</i> on the stability of time series of typhoid cases in an endemic community: variation in the number of monthly cases.

<p>Analysis of simulations using similar parameters to Fig. 11, showing the coefficient of variation in the number of monthly cases and using a more detailed range of probabilities of becoming a carrier. As for Fig. 11, endemic typhoid was not possible at low values of <i>R_c</i> and at low probabilities of becoming a carrier.</p