Laboratory of Molecular Microbiology of Human Pathogens, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal.
Sci Rep. 2022 May 7;12(1):7510. doi: 10.1038/s41598-022-11279-5.
Understanding how pneumococci respond to pneumococcal conjugate vaccines (PCVs) is crucial to predict the impact of upcoming higher-valency vaccines. However, stages in pneumococcal community succession following disturbance are poorly understood as long-time series on carriage are scarce and mostly evaluated at end-point measurements. We used a 20-year cross-sectional dataset of pneumococci carried by Portuguese children, and methods from community ecology, to study community assembly and diversity following use of PCV7 and PCV13. Two successional stages were detected upon introduction of each PCV: one in which non-vaccine serotypes increased in abundance, fitted by a broken-stick model, and a second in which the community returned to the original structure, fitted by a geometric series, but with different serotype profile and a drop in richness as great as 24%. A peak in diversity was observed for levels of intermediate vaccine uptake (30-40%) in agreement with the intermediate disturbance hypothesis. Serotype replacement was fitted by an exponential decay model (R = 80%, P < 0.001). The half-life for replacement was 8 years for PCV7 and 10 years for PCV13. The structure of the pneumococcal community is resilient to vaccine pressure. The increasing loss of diversity, however, suggests it could eventually reach a threshold beyond which it may no longer recover.
了解肺炎球菌对肺炎球菌结合疫苗（PCV）的反应对于预测即将推出的更高价疫苗的影响至关重要。然而，由于长期携带的时间序列稀缺且大多在终点测量时进行评估，因此对干扰后肺炎球菌群落演替的阶段知之甚少。我们使用了葡萄牙儿童携带的肺炎球菌 20 年的横断面数据集，并采用群落生态学方法，研究了使用 PCV7 和 PCV13 后群落的组装和多样性。在每种 PCV 引入时，都检测到了两个演替阶段：一个是疫苗非型别丰富度增加的阶段，用断枝模型拟合；另一个是社区恢复到原始结构的阶段，用几何级数拟合，但具有不同的血清型谱和高达 24%的丰富度下降。在中间疫苗接种水平（30-40%）观察到多样性峰值，这与中度干扰假说一致。血清型替代用指数衰减模型拟合（R=80%，P<0.001）。PCV7 的替换半衰期为 8 年，PCV13 的半衰期为 10 年。肺炎球菌群落的结构对疫苗压力具有弹性。然而，多样性的不断丧失表明，它最终可能会达到一个无法恢复的阈值。
