Effectiveness of 13-valent pneumococcal conjugate vaccine against vaccine-serotype community acquired pneumococcal diseases among children in China: A test-negative case-control study

BACKGROUND

In 2016, China licensed 13-valent pneumococcal conjugate vaccine (PCV13) based on a study that demonstrated its immunogenicity is non-inferior to PCV7. However, the real-world effectiveness of PCV13 against vaccine-serotype pneumococcal diseases in China has limited evidence.

METHODS

A test-negative case-control study was conducted among children under 5 years old admitted to the Children's Hospital of Soochow University (SCH) with respiratory tract infections from January 2018 to December 2020. Cases were defined as children from whom the isolates were tested positive for Streptococcus pneumoniae (S. pneumoniae) with serotypes included in PCV13. Two control groups were included, one represented children with isolates positive for S. pneumoniae of non-PCV13 serotypes and the other comprised children who tested negative for S. pneumoniae. The S. pneumoniae-negative controls were selected by matching them to the cases based on gender, age and admission date in a 1:1 ratio. Vaccine effectiveness (VE) was calculated using a logistic regression model as (1- adjusted odds ratio) * 100 %.

RESULTS

A total of 2371 pneumococcal isolates were included in the analysis, of which 75.0 % (1779/2371) were covered by PCV13 serotypes. Consequently, these 1779 children were classified as cases, and 592 children were designated as non-PCV13 serotype controls. Another 1779 children were correspondingly recruited as S. pneumoniae-negative controls. Overall, 40 cases (2.3 %) and 148 controls (6.2 %) had received vaccination. The overall VE in the PCV13/non-PCV13 serotypes case-control study was 50.0 % (95 % CI: 15.0, 70.7), which was lower than the VE of 74.4 % (95 % CI: 60.7, 83.3) in the matched PCV13/S. pneumoniae-negative case-control study. VE was higher for ≥ 2 or ≥ 3 doses of vaccination compared to ≥ 1 dose. VE against specific PCV13 serotypes (6B, 6A and 19F) was higher than for other serotypes.

CONCLUSIONS

PCV13 vaccination demonstrates effectiveness against vaccine-serotype pneumococcal diseases in children, particularly for serotypes 6B, 6A and 19F.

Agonist-induced down-regulation of alpha(1B)-adrenergic receptor in HEK293 cells transfected with alpha(1B) cDNA

HEK293 cells stably expressing hamster alpha(1B)-adrenergic receptor (alpha(1B)-AR) were used to observe the effect of nonepinephrine (NE) on alpha(1B)-AR gene expression. Radioligand binding assys and RNase protection assays were used to determine alpha(1B)-AR number and the mRNA level, respectively. Exposure (2-24 h) of HEK293 cella to NE (10 mumol) caused a decrease in alpha(1B)-AR mRNA with maximum change found at the 4th hour. and in alpha(1B)-AR density at the 24th hour. NE-induced decrease in alpha(1B)-AR mRNA was inhibited by protein kinase C (PKC) inhibitor calphostin C (0.1. mumol) and mimicked by PKC activator PMA (1 mumol). Nuclear run-off transcription assay showed that treatment of the cells with NE (10 mumol) exerted no effect on the transcription rate of alpha(1B)-AR, After the synthesis of new RNAs was inhibited by actinomycin D, NE muld not accelerate the degradation of alpha(1B)-AR mRNA. The results suggested that in the HEK293 cells NE muld induce the down-regulation of alpha(1B)-AR, and the effects were mediated by PKC pathway. NE could not alter the transcription rate of alpha(1B)-AR mRNA, but it might induce the synthesis of some factors and indirectly accelerate the degradation.

The preparation of HEK293 α1A or HEK293 α1B cell membrane stationary phase and the chromatographic affinity study of ligands of α1 adrenoceptor

As a novel bioaffinity chromatographic technique, cell membrane chromatography (CMC) originated in 1996. The cell membrane stationary phase (CMSP) consists of porous silica coated with active cell membranes. By immersing silica into a suspension of cell membranes, the whole surface of silica was covered by the cell membranes. The present study repeatedly investigated the interaction between ligands and receptors by employing the system of CMC and especially evaluated the accuracy and feasibility of the CMC model in the study of subtype receptors. The cDNA encoding alpha1A or alpha1B adrenergic receptors (ARs) was transfected into human embryonic kidney 293 (HEK293) cell lines; cell lines stably overexpressing subtype receptors were obtained. HEK293 alpha1A or HEK293 alpha1B ARs CMSP were prepared by immobilizing relevant cell membranes on silica. In the described chromatography-based CMSP, the retention times of nine alpha1 adrenoceptor ligands and calculated capacity factors, as chromatographic parameters, were recorded carefully. These results showed a good correlation with the affinity of the same compounds for the corresponding cloned alpha1 adrenoceptor subtype. The rank order of capacity factors was consistent with the affinity rank order obtained from radioligand binding assays. The immobilized subtype-selective CMSP was stable and reproducible. The study demonstrates that the HEK293 alpha1A and HEK293 alpha1B CMSP can be utilized for initial screening of drug candidates.

a1A-adrenergic receptor mediated pressor response to phenylephrine in anesthetized rat

To determine which subtype of alpha1-adrenergic receptors plays a role in the regulation of blood pressure, with alpha1A-adrenergic receptor-mediated vasoconstriction in perfused hindlimb as a control, we compared the inhibitory effects of various alpha1-adrenergic receptor selective antagonists on the vasopressure responses to phenylephrine between the mean arterial pressure and hindlimb perfusion pressure in anesthetized rats. In Normotensive Wistar rats, the results showed that the inhibitory effects (dose ratios of ED50, Dr) of alpha1-adrenoceptor selective antagonist (prazosin, Dr 13.5+/-3.6 vs.15.1+/-4.3, n = 11), alpha1A-adrenoceptor selective antagonist (5-methyl-urapidil, Dr 2.4+/-0.9 vs. 3.7+/-2.3, n = 12; RS-17053, Dr 3.2+/-1.6 vs. 4.4+/-3.3, n =12) and alpha1D-adrenoceptor selective antagonist (BMY7378, Dr 1.9+/-0.9 vs. 2.2+/-0.8, n=8) on phenylephrine- induced increases of perfusion pressure in the autoperfused femoral beds were the same as that in the mean arterial blood pressure in normotensive Wistar rats. The inhibitory effects of antagonists (RS-17053, Dr 3.4+/-0.6 vs. 4.3+/-0.9, n = 5; BMY7378, Dr 1.7+/-0.5 vs. 1.7+/-0.5, n = 8) in spontaneous hypertensive rats were similar with the Wistar rats. These results suggest that the mean arterial pressure induced by phenylephrine was mainly mediated by alpha1A-adrenergic receptor in both the anesthetized Wistar rats and spontaneous hypertensive rats.