Development of an mRNA vaccine against a panel of heterologous H1N1 seasonal influenza viruses using a consensus hemagglutinin sequence.

Seasonal influenza, causes hundreds of thousands of deaths annually, posing a severe threat to human health. Currently available influenza vaccines are targeted only at specific strains or conserved epitopes; however, these vaccines are not completely efficacious because influenza viruses can undergo mutation during circulation, leading to antigenic mismatch between recommended strains and circulating strains and elusion from the immune system. Therefore, developing an influenza vaccine that is quick, effective, and broadly protective has become crucial, and the integral part of hemagglutinin (HA) remains an ideal target for vaccine development. This study developed a lipid nanoparticle-encapsulated nucleoside-modified mRNA vaccine (mRNA-LNPs) encoding a consensus full-length HA sequence (H1c) and evaluated its protective efficacy and immunogenicity through in vitro and in vivo assays. Following two intramuscular immunizations (2, 10 µg, or 20 µg) at a 3-week interval in BALB/c mice, H1c-mRNA-LNP vaccine induced strong antibodies as shown in the hemagglutination-inhibition test and protective neutralizing antibodies against numerous heterologous H1N1 influenza viruses as shown in the microneutralization assay. Additionally, both Th1- and Th2-biased cellular immune responses were elicited, with the Th1-biased response being stronger. Two doses of the H1c-mRNA-LNP vaccine could neutralize a panel of heterologous H1N1 influenza viruses and could confer protection in mice. Taken together, these findings suggest that the H1c-mRNA-LNP vaccine encoding a consensus full-length HA is a feasible strategy for developing a cross-protective vaccine against a panel of heterologous H1N1 influenza viruses.

Effects of mid-myocardial pacing on transmural dispersion of repolarization and arrhythmogenesis.

INTRODUCTION: Epicardial (Epi) activation of the left ventricular (LV) wall increases transmural dispersion of repolarization (TDR), which creates a substrate for the development of ventricular arrhythmia. We hypothesize that pacing from the LV mid-myocardium may decrease the TDR and occurrence of arrhythmias. METHODS AND RESULTS: A transmural electrocardiogram and transmembrane action potentials were simultaneously recorded from Epi, mid-myocardial (M), and endocardial (Endo) layers of the arterially perfused canine LV wedge preparations (n= 8). Transmural dispersion of repolarization varied when the preparations were paced at each layer, respectively (Endo pacing, 35.6 ± 6.6 ms; M pacing, 34.9 ± 7.3 ms; Epi pacing, 72.4 ± 4.9 ms; P< 0.001). A significant difference was noted in TDR between M pacing and Epi pacing (P< 0.001), but not between M pacing and Endo pacing (P= 0.831). This result was reproducible in the presence of ischaemia-reperfusion experiments (n= 8). Transmural dispersion of repolarization was amplified as compared with non-ischaemic experiments and differed when preparations were paced at each layer (Endo pacing, 62.8 ± 13.8 ms; M pacing, 63.3 ± 13.3 ms; Epi pacing, 111.1 ± 17.7 ms; P< 0.001). There was again no significant difference between Endo pacing and M pacing (P= 0.948). However, as pacing was shifted from M to Epi, there was a significant increase in TDR (P< 0.001). Ventricular arrhythmias were induced in two of eight ischaemic preparations during Epi pacing, but did not occur in either M or Endo pacing. CONCLUSION: Mid-myocardial pacing can significantly decrease the TDR and prevent the occurrence of ventricular arrhythmias as compared with Epi pacing.

Catheter ablation of cardiac fat pads attenuates Bezold-Jarisch reflex in dogs.

BACKGROUND: Bezold-Jarisch reflex (BJR) plays an important role in the pathophysiology of several cardiovascular disorders. Radiofrequency catheter ablation (RFCA) of the vagal ganglia in cardiac fat pads (FPs) may attenuate BJR. The purpose of this study was to examine the effects of RFCA of the cardiac FPs on veratridine-induced BJR in dogs. METHODS AND RESULTS: This study was performed in 30 pentobarbital-anesthetized and open-chest dogs: control group received no ablation (n = 15); and ablation group (n = 15) received epicardial ablation of the 3 FPs located near the right pulmonary vein, the inferior vena cava, and the aortic root. The BJR was induced by injection of veratridine (15 µg/kg) into the left ventricle. Before injection of veratridine, there were no significant differences in heart rate (HR), systolic arterial pressure (SAP), diastolic arterial pressure (DAP), mean arterial pressure (MAP), left ventricular systolic pressure (LVSP), left ventricle end-diastolic pressure (LVEDP), left ventricular peak systolic and diastolic velocity (±dp/dt(max)) between these 2 groups (P > 0.05). However, the veratridine-induced decrease of HR in ablation group was significantly lower than that in control group (22.9 ± 8.5 bpm vs 93.3 ± 18.4 bpm, P < 0.01). There were no differences in the reduction of SAP, DAP, MAP, LVSP, LVEDP and dp/dt(max) between both groups (P > 0.05). CONCLUSIONS: RFCA of the cardiac FPs significantly attenuated veratridine-induced cardio-vagal component but not the vasodepressor component of the BJR. This might have therapeutic implications in BJR-related disorders such as cardio-inhibitory vasovagal syncope.

Association of the interferon-gamma single nucleotide polymorphism +874(T/A) with response to immunosuppressive therapy in patients with severe aplastic anemia.

The aim of this study was to investigate whether a single nucleotide polymorphism (SNP) +874T/A of interferon-gamma (IFN-γ) correlates with response to immunosuppressive therapy. Amplification refractory mutation system-polymerase chain reaction was used to amplify the polymorphic segments of the IFN-γ +874T/A gene in the samples obtained from 54 patients with aplastic anemia and 51 healthy adults. Further, enzyme linked immunosorbent assay was used to assay IFN-γ levels in the blood plasma of 35 patients with severe aplastic anemia before immune suppression therapy and 20 healthy blood donors. The results showed that the frequency of IFN-γ +874 TT genotype in patients with aplastic anemia was significantly higher than the corresponding frequency in the healthy adults (42.6% vs. 17.6%, χ(2)=13.78, p=0. 01). The response rate in severe aplastic anemia patients with increased IFN-γ levels in the blood plasma was higher than that in severe aplastic anemia patients with decreased IFN-γ levels in the blood plasma (73.7% vs. 25.0%, p<0.05). Of the 35 patients with severe aplastic anemia, 15 showed the IFN-γ +874 TT genotype, whereas response in 11 patients, the high response rate was significantly in the favor of the IFN-γ +874 TT genotype (73.3% vs. IFN-γ +874 non-TT 35%, p<0.05). In conclusion, the IFN-γ +874T/A gene polymorphism may be correlated with response to immunosuppressive therapy.

[The polymorphism of interferon gamma gene CA short tandem repeat is associated with aplastic anemia].

OBJECTIVE: To explore the possible relationship between the polymorphism of CA short tandem repeat in first intron of interferon-gamma (IFN-gamma) gene and the susceptibility of aplastic anemia. METHODS: 54 patients, who were diagnosed as acquired aplastic anemia in West China Hospital of Sichuan University when it was from February 2006 to March 2007, and simultaneously 51 healthy adults were enrolled as normal control for this project. The polymerase chain reaction and polyacrylamide gel electrophoresis were used to assay the polymorphism of CA short tandem repeat. RESULTS: The frequency of the homozygous for 12-12 (CA) repeats or the single allele 12 (CA) repeats of the patients was 18.52% or 50.92% respectively, which was obviously higher than the control group's frequency which was 2.00% or 26.47% (P = 0.008, P < 0.001 respectively). The frequency of the homozygous for 12 (CA) repeats or the single allele 12 (CA) in acute aplastic anemia group was 12. 00% or 48.00%, while in the chronic aplastic anemia group that frequency was 24.14% or 53.45%, the statistic analysis showed there was no significant difference between those two groups (chi2 = 1.311, P = 0.252, chi2 = 0.319, P = 0.572). CONCLUSION: This study suggests that: IFN-gamma CA short tandem repeat polymorphism is associated with the susceptibility of aplastic anemia but has no relation to the severity of the aplastic anemia.

Effects of early intravenous low-dose of metoprolol on cardiac sympathetic activities and electrophysiological properties in myocardial infarction heart.

This study observed the effects of early intravenous low-doses of metoprolol on cardiac sympathetic activities and electrophysiological properties in myocardial infarction (MI) dogs. Thirty two mongrel dogs with the first diagonal branch of the left anterior descending coronary artery ligated were randomly divided into three groups: The low-dose group was given metoprolol 0.6 mg/kg immediately by intravenous injection (n=12); the target-dose group was given metoprolol 1.6 mg/kg (n=12), and the control group was injected with normal saline at the same dose of the target-dose group (n=8). Norepinephrine (NE) and epinephrine (E) levels in the coronary sinus (CS) blood as well as the ventricular effective refractory period (ERP) were all measured during the experiments. We found that NE and E concentrations in the three groups were all increased compared with the previous measurement before ligation. ERP values after MI were significantly decreased in all three groups compared with the first measurements. The three groups all exhibited uneven shortness of ERP among different regions, with significant shortness in infarcted area. Furthermore, there was no difference between the low and target-dose of metoprolol in the reduction of regional ERP, and the same effect was also observed in induced arrhythmias. In conclusion, a lower dose of metoprolol performed similarly as target-dose in reducing the catecholamine concentrations in dogs with MI. Our study demonstrated that a lower dose of metoprolol may be reasonable compared with the target-dose in ß-blocker therapy due to similar effect and lower toxicity.

[Single nucleotide polymorphism of interferon-gamma gene +874 T/A in patients with aplastic anemia].

The aim of this study was to investigate whether the single nucleotide polymorphism (SNP) of interferon-gamma (IFN-gamma) +874 T/A correlates with aplastic anemia. Amplification refractory mutation system-polymerase chain reaction was used to amplify the polymorphism gene segment of IFN-gamma +874 A/T from 54 aplastic anemia patients and 51 healthy adults. The results showed that the frequency of IFN-gamma +874 TT genotype and T allele was significantly higher in patients with aplastic anemia than that in the healthy adults (42.6% vs 17.6%, chi2=13.780, p=0.01; 65.7% vs 39.2%; chi2=14.811, p<0.001). In conclusion, IFN-gamma +874 A/T gene polymorphism is correlated with the susceptibility of aplastic anemia, but not significantly correlated with the the severity of aplastic anemia.