Schachern Patricia A, Tsuprun Vladimir, Ferrieri Patricia, Briles David E, Goetz Sarah, Cureoglu Sebahattin, Paparella Michael M, Juhn Steven
Departments of Otolaryngology, University of Minnesota, Minneapolis, MN, United States.
Departments of Otolaryngology, University of Minnesota, Minneapolis, MN, United States.
Int J Pediatr Otorhinolaryngol. 2014 Sep;78(9):1517-21. doi: 10.1016/j.ijporl.2014.06.024. Epub 2014 Jun 24.
Otitis media is the most commonly diagnosed disease in ambulatory care and Streptococcuspneumoniae continues to be the most common bacterial agent. Bacterial resistance to antibiotics underscores the need for better vaccines. Current pneumococcal conjugate vaccines are modestly protective against otitis media; however, limited serotype coverage and serotype replacement have led to the investigation of pneumococcal proteins as potential vaccine candidates. Two proteins, pneumococcal surface proteins A (PspA) and C (PspC) are important virulence factors, expressed by virtually all strains. Although a number of pneumococcal proteins have been investigated in other infection sites, these proteins can have diverse organ-specific effects. In this study, we investigated the viability and virulence of single (PspA(-) and PspC(-)) and double (PspA(-)/PspC(-)) mutants of pneumococcal PspA and PspC proteins in the chinchilla middle ear.
Bullae of 24 chinchillas were inoculated with 0.5 ml of 10(6) colony forming units (CFUs)/ml bacteria: 6 with wild-type D39 strain; 6 with PspA(-); 6 with PspC(-); and 6 with PspA(-)/PspC(-) isogenic mutant strains. Bacterial CFU levels in middle ear effusions and light microscopic analysis of the number of inflammatory cells in the round window membrane (RWM) were compared 48 h after inoculation.
At 48 h, CFUs in middle ears were increased for wild-type and PspC(-) strains compared to inoculum levels; however, they were significantly less for the group inoculated with the PspC(-) strain compared to wild-type strain. No bacteria were detected in the PspA(-) and PspA(-)/PspC(-) groups. The number of inflammatory cells in the RWM was significantly higher in wild-type compared to the PspA(-), PspC(-), and PspA(-)/PspC(-) groups. No significant difference in number of inflammatory cells was observed between any pairs of groups inoculated with mutant strains.
Viability and virulence of the PspC(-) strain were similar to the wild-type strain. The single PspA(-) and double PspA(-)/PspC(-) mutants were highly attenuated in the ear. Bacterial clearance of the PspA(-)/PspC(-) double mutant was indistinguishable from that of the PspA mutant. These studies provide no reason to exclude PspC from a multi-component protein vaccine containing PspA.
中耳炎是门诊最常诊断出的疾病，肺炎链球菌仍是最常见的致病细菌。细菌对抗生素的耐药性凸显了研发更好疫苗的必要性。目前的肺炎球菌结合疫苗对中耳炎有一定的保护作用；然而，血清型覆盖范围有限和血清型替换促使人们对肺炎球菌蛋白作为潜在疫苗候选物进行研究。两种蛋白，肺炎球菌表面蛋白A（PspA）和C（PspC）是重要的毒力因子，几乎所有菌株都能表达。尽管已经在其他感染部位对多种肺炎球菌蛋白进行了研究，但这些蛋白可能具有不同的器官特异性作用。在本研究中，我们调查了肺炎球菌PspA和PspC蛋白的单突变体（PspA(-)和PspC(-)）及双突变体（PspA(-)/PspC(-)）在灰鼠中耳中的生存能力和毒力。
给24只灰鼠的鼓室接种0.5 ml含10(6)个菌落形成单位（CFU）/ml细菌的菌液：6只接种野生型D39菌株；6只接种PspA(-)；6只接种PspC(-)；6只接种PspA(-)/PspC(-)同基因突变菌株。接种48小时后，比较中耳积液中的细菌CFU水平以及圆窗膜（RWM）中炎性细胞数量的光镜分析结果。
48小时时，野生型和PspC(-)菌株中耳内的CFU相比接种时有所增加；然而，与野生型菌株相比，接种PspC(-)菌株组的CFU显著减少。在PspA(-)组和PspA(-)/PspC(-)组未检测到细菌。与PspA(-)、PspC(-)和PspA(-)/PspC(-)组相比，野生型RWM中的炎性细胞数量显著更高。接种突变菌株的各组之间，炎性细胞数量未观察到显著差异。
PspC(-)菌株的生存能力和毒力与野生型菌株相似。单突变体PspA(-)和双突变体PspA(-)/PspC(-)在耳部高度减毒。PspA(-)/PspC(-)双突变体的细菌清除情况与PspA突变体无法区分。这些研究没有理由将PspC排除在含有PspA的多组分蛋白疫苗之外。
