Sequential Immunizations with Influenza Neuraminidase Protein Followed by Peptide Nanoclusters Induce Heterologous Protection.

Enhancing cross-protections against diverse influenza viruses is desired for influenza vaccinations. Neuraminidase (NA)-specific antibody responses have been found to independently correlate with a broader influenza protection spectrum. Here, we report a sequential immunization regimen that includes priming with NA protein followed by boosting with peptide nanoclusters, with which targeted enhancement of antibody responses in BALB/c mice to certain cross-protective B-cell epitopes of NA was achieved. The nanoclusters were fabricated via desolvation with absolute ethanol and were only composed of composite peptides. Unlike KLH conjugates, peptide nanoclusters would not induce influenza-unrelated immunity. We found that the incorporation of a hemagglutinin peptide of H2-d class II restriction into the composite peptides could be beneficial in enhancing the NA peptide-specific antibody response. Of note, boosters with N2 peptide nanoclusters induced stronger serum cross-reactivities to heterologous N2 and even heterosubtypic N7 and N9 than triple immunizations with the prototype recombinant tetrameric (rt) N2. The mouse challenge experiments with HK68 H3N2 also demonstrated the strong effectiveness of the peptide nanocluster boosters in conferring heterologous protection.

2-Bromopalmitate inhibits malignant behaviors of HPSCC cells by hindering the membrane location of Ras protein.

Palmitoylation, which is mediated by protein acyltransferase (PAT) and performs important biological functions, is the only reversible lipid modification in organism. To study the effect of protein palmitoylation on hypopharyngeal squamous cell carcinoma (HPSCC), the expression levels of 23 PATs in tumor tissues of 8 HPSCC patients were determined, and high mRNA and protein levels of DHHC9 and DHHC15 were found. Subsequently, we investigated the effect of 2-bromopalmitate (2BP), a small-molecular inhibitor of protein palmitoylation, on the behavior of Fadu cells in vitro (50 µM) and in nude mouse xenograft models (50 µmol/kg), and found that 2BP suppressed the proliferation, invasion, and migration of Fadu cells without increasing cell apoptosis. Mechanistically, the effect of 2BP on the transduction of BMP, Wnt, Shh, and FGF signaling pathways was tested with qRT-PCR, and its drug target was explored with western blotting and acyl-biotinyl exchange assay. Our results showed that 2BP inhibited the transduction of the FGF/ERK signaling pathway. The palmitoylation level of Ras protein decreased after 2BP treatment, and its distribution in the cell membrane structure was reduced significantly. The findings of this work reveal that protein palmitoylation mediated by DHHC9 and DHHC15 may play important roles in the occurrence and development of HPSCC. 2BP is able to inhibit the malignant biological behaviors of HPSCC cells, possibly via hindering the palmitoylation and membrane location of Ras protein, which might, in turn, offer a low-toxicity anti-cancer drug for targeting the treatment of HPSCC.

Predicting acute radiation dermatitis in breast cancer: a prospective cohort study.

BACKGROUND: Acute radiation dermatitis (ARD) is one of the most common acute adverse reactions in breast cancer patients during and immediately after radiotherapy. As ARD affects patient quality of life, it is important to conduct individualized risk assessments of patients in order to identify those patients most at risk of developing severe ARD. METHODS: The data of breast cancer patients who received radiotherapy were prospectively collected and analyzed. Serum ferritin, high-sensitivity C-reactive protein (hs-CRP) levels, and percentages of lymphocyte subsets were measured before radiotherapy. ARD was graded (0-6 grade), according to the Oncology Nursing Society Skin Toxicity Scale. Univariate and multivariate logistic regression analyses were used and the odds ratio (OR) and 95% confidence interval (CI) of each factor were calculated. RESULTS: This study included 455 breast cancer patients. After radiotherapy, 59.6% and 17.8% of patients developed at least 3 (3+) grade and at least 4 (4+) grade ARD, respectively. Multivariate logistic regression analysis found that body mass index (OR: 1.11, 95% CI: 1.01-1.22), diabetes (OR: 2.70, 95% CI: 1.11-6.60), smoking (OR: 3.04, 95% CI: 1.15-8.02), higher ferritin (OR: 3.31, 95% CI: 1.78-6.17), higher hs-CRP (OR: 1.96, 95% CI: 1.02-3.77), and higher CD3 + T cells (OR: 2.99, 95% CI: 1.10-3.58) were independent risk factors for 4 + grade ARD. Based on these findings, a nomogram model of 4 + grade ARD was further established. The nomogram AUC was 0.80 (95% CI: 0.75-0.86), making it more discriminative than any single factor. CONCLUSION: BMI, diabetes, smoking history, higher ferritin, higher hs-CRP, and higher CD3 + T cells prior to radiotherapy for breast cancer are all independent risk factors for 4 + grade ARD. The results can provide evidence for clinicians to screen out high-risk patients, take precautions and carefully follow up on these patients before and during radiotherapy.

Complete response in patient with liver metastasis of HER2-positive breast cancer following therapy with margetuximab: a case report.

Metastatic human epidermal growth factor receptor 2 (HER2) positive breast cancer has a poor prognosis and few effective targeted therapies. However, several anti-HER2 agents are emerging in conjunction with chemotherapy, which may lead to increased rates of pathological complete response in patients with HER2-positive metastatic breast cancer. Among them, margetuximab demonstrated a significant improvement in progression-free survival compared with trastuzumab, when combined with chemotherapy in pretreated patients. Here we present a case of a 67-year-old female patient who was diagnosed with HER2-positive, histological grade III and invasive ductal carcinoma of the left breast in September 2018. She received postoperative adjuvant therapy with EC-TH plus radiotherapy, followed by therapy with HER2-targeted trastuzumab for 1 year (till December 2019). In May 2020, routine reexamination showed a supraclavicular lymph node and bone metastasis. Patient was then treated with pyrotinib, capecitabine and bisphosphonate for a period of 3 months. In December 2020, liver MRI revealed multiple liver metastases. The patient received eight cycles of second-line therapy (vinorelbine plus margetuximab) from January 2021. Since the ninth cycle, the patient was continued with only margetuximab. In March 2021, MRI showed a 70% decrease in the liver metastasis lesions. By June 2021, liver lesions were totally disappeared. During therapy, patient experienced only grade-1 anemia. This case demonstrates that margetuximab plus chemotherapy is safe and might bring clinical benefits for patients with HER2-positive breast cancer with liver metastasis. Further studies evaluating the efficacy and safety of margetuximab in Chinese HER2-positive breast cancer patients are needed.

Effect of a Novel Soaking Solution Used in Patients With Hand-Foot Syndrome as a Result of Capecitabine Treatment: A Randomized and Self-Controlled Trial.

BACKGROUND: Hand-foot syndrome (HFS) is a common adverse event in patients receiving capecitabine therapy for breast cancer, and the symptoms of HFS significantly impair patient quality of life. However, currently there are no effective drugs or measures to prevent and alleviate the occurrence of HFS. AIM: To assess the effectiveness of a novel soaking solution, a mixture solution of dexamethasone, gentamicin and vitamin B12, in patients with grade 2-3 HFS after capecitabine treatment for breast cancer. MATERIALS AND METHODS: Patients with grade 2-3 HFS according to the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) were enrolled in this randomized, single-center, self-controlled trial. Each patient's right and left hands or feet were individually randomized to soak in either a novel soaking solution (treated hands or feet) or a placebo liquid (control hands or feet) for three times a day, each time for 15 minutes and for four weeks. Effectiveness was evaluated according to CTCAE grades, defined as a reduction of 1 or more CTCAE grades. RESULTS: A total of 60 patients were enrolled. The HFS CTCAE grade of the treated hands and feet at 4 weeks of HFS treatment was significantly decreased compared to that of the control hands and feet (P = .005). Significant differences were also observed between the treatment conditions in terms of the HFS effectiveness rate: treated group 80% and placebo group 51.7% (P = .001). No adverse or unexpected events were observed during the whole trial. CONCLUSION: Soaking affected hands or feet in a novel soaking solution safely and effectively reduced the severity of HFS following treatment with capecitabine for breast cancer.

Validation and Application of the Chinese Version of the M. D. Anderson Symptom Inventory in Breast Cancer Patients.

OBJECTIVE: To validate and use the Chinese Version of the M. D. Anderson Symptom Inventory (MDASI-C) to assess the symptom burden of breast cancer patients in China. METHODS: A total of 342 breast cancer patients in China participated in this study. Their symptoms were investigated with the MDASI-C from November 2020 to February 2021, and the reliability and validity of this tool were evaluated, respectively. Cluster analysis and correlation analysis were also performed. RESULTS: The Cronbach's alpha coefficient values of the symptom and interference items were 0.827 and 0.880, respectively. Construct validity revealed a four-factor structure. The Kaiser-Meyer-Olkin value was 0.760. The Karnofsky Performance Status, treatment phase, and cancer stage of the patients were grouped, and the differences of scores within the groups were significant. In addition, the employment status, education level, and age of the patients were significantly correlated with the symptoms. The correlation analysis of the education level of the patients showed that most of the symptoms and interference items were reduced as the education level was increased. The top three symptoms were disturbed sleep (3.10±2.52), difficulty remembering (2.54±2.30), and fatigue (2.24±2.13). The clinical and biochemical indicators such as body mass index and neutral granulocyte lymphocyte ratio had effects on many symptoms. As the patients' BMI increased, the patients' pain, disturbed sleep, and difficulty remembering were aggravated, and numbness was alleviated. CONCLUSION: The MDASI-C is a reliable and effective assessment tool to evaluate patients with breast cancer in China. The symptoms are related to many clinical and biochemical indicators.

Risk Factors Related to Acute Radiation Dermatitis in Breast Cancer Patients After Radiotherapy: A Systematic Review and Meta-Analysis.

BACKGROUND: Acute radiation dermatitis (ARD) is the most common acute response after adjuvant radiotherapy in breast cancer patients and negatively affects patients' quality of life. Some studies have reported several risk factors that can predict breast cancer patients who are at a high risk of ARD. This study aimed to identify patient- and treatment-related risk factors associated with ARD. METHODS: PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, and WanFang literature databases were searched for studies exploring the risk factors in breast cancer patients. The pooled effect sizes, relative risks (RRs), and 95% CIs were calculated using the random-effects model. Potential heterogeneity and sensitivity analyses by study design, ARD evaluation scale, and regions were also performed. RESULTS: A total of 38 studies composed of 15,623 breast cancer patients were included in the analysis. Of the seven available patient-related risk factors, four factors were significantly associated with ARD: body mass index (BMI) ≥25 kg/m2 (RR = 1.11, 95% CI = 1.06-1.16, I 2 = 57.1%), large breast volume (RR = 1.02, 95% CI = 1.01-1.03, I 2 = 93.2%), smoking habits (RR = 1.70, 95% CI = 1.24-2.34, I 2 = 50.7%), and diabetes (RR = 2.24, 95% CI = 1.53-3.27, I 2 = 0%). Of the seven treatment-related risk factors, we found that hypofractionated radiotherapy reduced the risk of ARD in patients with breast cancer compared with that in conventional fractionated radiotherapy (RR = 0.28, 95% CI = 0.19-0.43, I 2 = 84.5%). Sequential boost and bolus use was significantly associated with ARD (boost, RR = 1.91, 95% CI = 1.34-2.72, I 2 = 92.5%; bolus, RR = 1.94, 95% CI = 1.82-4.76, I 2 = 23.8%). However, chemotherapy regimen (RR = 1.17, 95% CI = 0.95-1.45, I 2 = 57.2%), hormone therapy (RR = 1.35, 95% CI = 0.94-1.93, I 2 = 77.1%), trastuzumab therapy (RR = 1.56, 95% CI = 0.18-1.76, I 2 = 91.9%), and nodal irradiation (RR = 1.57, 95% CI = 0.98-2.53, I 2 = 72.5%) were not correlated with ARD. Sensitivity analysis results showed that BMI was consistently associated with ARD, while smoking, breast volume, and boost administration were associated with ARD depending on study design, country of study, and toxicity evaluation scale used. Hypofractionation was consistently shown as protective. The differences between study design, toxicity evaluation scale, and regions might explain a little of the sources of heterogeneity. CONCLUSION: The results of this systematic review and meta-analysis indicated that BMI ≥ 25 kg/m2 was a significant predictor of ARD and that hypofractionation was consistently protective. Depending on country of study, study design, and toxicity scale used, breast volume, smoking habit, diabetes, and sequential boost and bolus use were also predictive of ARD.

The Role and Mechanism of ATM-Mediated Autophagy in the Transition From Hyper-Radiosensitivity to Induced Radioresistance in Lung Cancer Under Low-Dose Radiation.

Objective: This study aimed to investigate the effect of ataxia telangiectasia mutated (ATM)-mediated autophagy on the radiosensitivity of lung cancer cells under low-dose radiation and to further investigate the role of ATM and its specific mechanism in the transition from hyper-radiosensitivity (HRS) to induced radioresistance (IRR). Methods: The changes in the HRS/IRR phenomenon in A549 and H460 cells were verified by colony formation assay. Changes to ATM phosphorylation and cell autophagy in A549 and H460 cells under different low doses of radiation were examined by western blot, polymerase chain reaction (PCR), and electron microscopy. ATM expression was knocked down by short interfering RNA (siRNA) transfection, and ATM-regulated molecules related to autophagy pathways were screened by transcriptome sequencing analysis. The detection results were verified by PCR and western blot. The differential metabolites were screened by transcriptome sequencing and verified by colony formation assay and western blot. The nude mouse xenograft model was used to verify the results of the cell experiments. Results: (1) A549 cells with high expression of ATM showed positive HRS/IRR, whereas H460 cells with low expression of ATM showed negative HRS/IRR. After the expression of ATM decreased, the HRS phenomenon in A549 cells increased, and the radiosensitivity of H460 cells also increased. This phenomenon was associated with the increase in the autophagy-related molecules phosphorylated c-Jun N-terminal kinase (p-JNK) and autophagy/Beclin 1 regulator 1 (AMBRA1). (2) DL-Norvaline, a product of carbon metabolism in cells, inhibited autophagy in A549 cells under low-dose radiation. DL-Norvaline increased the expression levels of ATM, JNK, and AMBRA1 in A549 cells. (3) Mouse experiments confirmed the regulatory role of ATM in autophagy and metabolism and its function in HRS/IRR. Conclusion: ATM may influence autophagy through p-JNK and AMBRA1 to participate in the regulation of the HRS/IRR phenomenon. Autophagy interacts with the cellular carbon metabolite DL-Norvaline to participate in regulating the low-dose radiosensitivity of cells.

Repression of the AURKA-CXCL5 axis induces autophagic cell death and promotes radiosensitivity in non-small-cell lung cancer.

Aurora kinase A (AURKA) regulates apoptosis and autophagy in various diseases and has shown promising clinical effects. Nevertheless, the complex regulatory mechanism of AURKA and autophagy in non-small-cell lung cancer (NSCLC) radiosensitivity remains to be elucidated. Here, we showed that AURKA was upregulated in NSCLC cell lines and tissues and that AURKA overexpression was significantly related to a poor prognosis, tumor stage and lymph node metastasis in NSCLC. Interestingly, AURKA expression was significantly increased after 8Gy radiotherapy. Silencing of AURKA enhanced radiosensitivity and impaired migration and invasion in vivo and in vitro. Mechanistically, we determined that CXCL5, a member of the chemokine family, was a key downstream effector of AURKA, and the phenotype induced by AURKA silencing was partly due to CXCL5 inhibition. We further demonstrated that the AURKA-CXCL5 axis played an essential role in NSCLC autophagy and that the activation of cytotoxic autophagy attenuated the malignant biological behavior of NSCLC cells mediated by AURKA-CXCL5. In general, we revealed the role of the AURKA-CXCL5 axis and autophagy in regulating the sensitivity of NSCLC cells to radiotherapy, which may provide potential therapeutic targets and new strategies for combatting NSCLC resistance to radiotherapy.

Intrahepatic Expression of C-C Motif ligand 5 in Patients with Chronic Hepatitis B.

BACKGROUND: C-C motif ligand 5 (CCL5) is reported to play a key role in acute and chronic liver diseases. However, the association between CCL5 and chronic hepatitis B (CHB) remains to be explored. We aimed to investigate the CCL5 expression in the liver tissues of CHB patients and compared the CCL5 expression among CHB patients with different stages of liver inflammation and fibrosis. METHODS: Liver tissue specimens from 51 CHB patients who underwent liver biopsy and twelve healthy liver donors were included in the present study. CCL5 expression in the liver tissues was analyzed using immunohistochemistry. The hepatic inflammation grades and fibrotic stages of CHB patients were assessed by the Scheuer classification system. RESULTS: Livers of CHB patients exhibited significantly accumulated CCL5+ cells when compared to those of healthy controls (42.80 ± 4.37 vs. 7.25 ± 0.99/HPF, P < .001). CHB patients with higher hepatic inflammation grades had more CCL5+ cells in their livers than those with lower grades (P < .05). However, the numbers of CCL5+ cells were not correlated with the fibrotic stages in CHB patients (r = .073, P = .61). The number of CCL5+ cells in the liver tissues of CHB patients was positively correlated with alanine transaminase levels (r = .278, P = .041) and aspartate aminotransferase levels (r = .328, P = .009). CONCLUSIONS: CHB patients have a significant accumulation of CCL5+ cells in the liver, and CCL5 may play a pathological role in hepatic inflammation of CHB.

HHLA2 overexpression is a novel biomarker of malignant status and poor prognosis in gastric cancer.

Human endogenous retrovirus-H long terminal repeat-associating protein 2 (HHLA2) is a newly identified member of B7 family; HHLA2 protein expression has been suggested to be increased levels in many kinds of human cancers. However, HHLA2 protein expression in gastric cancer tissues and its clinical significance are still unknown. The purpose of this study was to investigate the HHLA2 protein expression pattern in gastric cancer tissues and the correlation between HHLA2 protein expression and clinicopathological characteristics including clinical outcome in gastric cancer patients. In our results, we observed HHLA2 expression was increased in gastric cancer tissue specimens compared with normal stomach tissue specimens through analyzing HHLA2 expression data from 408 gastric cancer tissue specimens and 211 normal stomach tissue specimens at databases. Furthermore, we, respectively, performed quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and immunohistochemistry to verify HHLA2 mRNA and protein expressions in gastric cancer tissues and normal stomach tissues, and found HHLA2 mRNA and protein expressions were up-regulated in gastric cancer tissues. Moreover, we found high HHLA2 expression was correlated with advanced clinical stage, deep tumor invasion, lymph node metastasis, distant metastasis and short overall survival in gastric cancer. The multivariable Cox's proportional hazard models indicated high HHLA2 expression was a poor independent prognostic factor for overall survival in patients with gastric cancer. In conclusion, HHLA2 protein overexpression in gastric cancer tissue is potential risk factor for malignant status and poor prognosis.

Risk factors and mortality for patients with Bloodstream infections of Klebsiella pneumoniae during 2014-2018: Clinical impact of carbapenem resistance in a large tertiary hospital of China.

BACKGROUND: Bloodstream infection (BSI) caused by Klebsiella pneumoniae (KP), especially carbapenem-resistant KP (CRKP), results in high morbidity and mortality. AIMS: We aim to identify risk factors that associated with the mortality of patients with KP BSI, as well as predictors of developing CRKP BSI. RESULTS: In this retrospective cohort study, we examined 285 inpatients with BSI caused by KP in a tertiary hospital in China between 2014 and 2018, and 46 patients were infected with CRKP. We identified that hematological tumor (odds ratio (OR): 8.359, [95% CI: 2.162-33.721], P=0.002), CRKP isolation (OR: 7.766, [95% CI: 2.796-21.576], P=0.001), chronic lung disease (OR: 5.020, [95% CI: 1.275-19.768], P=0.020), and septic shock (OR: 4.591, [95% CI: 1.686-12.496], P=0.003) were independent risk factors for the death of KP BSI. A 28-day mortality of KP BSI score ranging from 0 to 22 was developed based on the above 4 independent variables. Our scoring system revealed that the 28-day mortality were 9.14%, 35.29%, 38.10 %, 75% and 100% for carriers with a score of 0, 5, 6-10, 11-13 and ≥14, respectively. Additionally, CRKP infection were independently associated with intensive care unit stay (OR: 5.506, [95% CI: 2.258-13.424], P=0.001), exposure to antifungals (OR: 4.679, [95% CI: 2.065-10.063], P=0.001), exposure to fluoroquinolones (OR: 2.892, [95% CI: 1.151-7.267], P=0.020), and the number of isolated bacterial species from the patient ≥ 3 (OR: 2.414, [95% CI: 1.306-4.463], P=0.005). CONCLUSION: Our study may be useful for the reduction of the mortality of patients with KP BSI and the prevention of developing CRKP BSI in hospitals.

Analyses on K-ras mutations and fascin expression in patients with cardia cancer.

Mutations of K-rat sarcoma (K-ras) in patients with cardia cancer and their effects on the expression of fascin were investigated. A total of 90 cardia cancer patients treated in Jining First People's Hospital from March 2014 to March 2017 were randomly selected. Genomic deoxyribonucleic acid (DNA) was extracted from paraffin-embedded cardia cancer specimens. Pyrosequencing was applied to detect sequences of K-ras gene in all patients and to analyze the mutations of K-ras gene. Then, genotyping of mutations at each mutation site was carried out using quantitative polymerase chain reaction (qPCR). The expression level of fascin in patients was measured via immunohistochemistry and qPCR. The results revealed that among 90 patients with cardia cancer, 21 patients had K-ras mutations (23.3%), including 20 cases of exon 12 mutation and 1 case of exon 13 mutation. Risk factor analyses revealed that alcohol abuse was a high risk factor for mutations (p<0.05). There was no significant difference in the mutation probability between heterozygotes and homozygotes for four mutations at codon 12 (p>0.05). The heterozygote at codon 13 had a higher mutation probability than homozygote (p<0.05). Immunohistochemistry suggested that the number of positive cells in the mutant group was larger than that in the non-mutant group (p<0.05). The results of qPCR showed that the expression level of fascin gene in the mutant group was 2.3 times higher than that in the non-mutant group (p<0.05). In conclusion, the probability of codon 12 mutation in K-ras gene is increased in patients with cardia cancer, and fascin is highly expressed in mutant patients, which is positively correlated with the mutations in K-ras gene.

A novel predictive model using routinely clinical parameters to predict liver fibrosis in patients with chronic hepatitis B.

OBJECTIVES: Noninvasive models have been established for the assessment of liver fibrosis in patients with chronic hepatitis B(CHB). However, the predictive performance of these established models remains inconclusive. We aimed to develop a novel predictive model for liver fibrosis in CHB based on routinely clinical parameters. RESULTS: Platelets(PLT), the standard deviation of red blood cell distribution width(RDW-SD), alkaline phosphatase(ALP) and globulin were independent predictors of significant fibrosis by multivariable analysis. Based on these parameters, a new predictive model namely APRG(ALP/PLT/RDW-SD/globulin) was proposed. The areas under the receiver-operating characteristic curves(AUROCs) of APRG index in predicting significant fibrosis(≥F2), advanced fibrosis(≥F3) and liver cirrhosis(≥F4) were 0.757(95%CI 0.699 to 0.816), 0.763(95%CI 0.711 to 0.816) and 0.781(95%CI 0.728 to 0.835), respectively. The AUROCs of the APRG were significantly higher than that of aspartate transaminase(AST) to PLT ratio index(APRI), RDW to PLT ratio(RPR) and AST to alanine aminotransferase ratio(AAR) to predict significant fibrosis, advanced fibrosis and cirrhosis. The AUROCs of the APRG were also significantly higher than fibrosis-4 score (FIB-4) (0.723, 95%CI 0.663 to 0.783) for cirrhosis(P=0.034) and better than gamma-glutamyl transpeptidase(GGT) to PLT ratio(GPR) (0.657, 95%CI 0.590 to 0.724) for significant fibrosis(P=0.001). MATERIALS AND METHODS: 308 CHB patients who underwent liver biopsy were enrolled. The diagnostic values of the APRG for liver fibrosis with other noninvasive models were compared. CONCLUSIONS: The APRG has a better diagnostic value than conventionally predictive models to assess liver fibrosis in CHB patients. The application of APRG may reduce the need for liver biopsy in CHB patients in clinical practice.

A single dose of DNA vaccine based on conserved H5N1 subtype proteins provides protection against lethal H5N1 challenge in mice pre-exposed to H1N1 influenza virus.

BACKGROUND: Highly pathogenic avian influenza virus subtype H5N1 infects humans with a high fatality rate and has pandemic potential. Vaccination is the preferred approach for prevention of H5N1 infection. Seasonal influenza virus infection has been reported to provide heterosubtypic immunity against influenza A virus infection to some extend. In this study, we used a mouse model pre-exposed to an H1N1 influenza virus and evaluated the protective ability provided by a single dose of DNA vaccines encoding conserved H5N1 proteins. RESULTS: SPF BALB/c mice were intranasally infected with A/PR8 (H1N1) virus beforehand. Six weeks later, the mice were immunized with plasmid DNA expressing H5N1 virus NP or M1, or with combination of the two plasmids. Both serum specific Ab titers and IFN-gamma secretion by spleen cells in vitro were determined. Six weeks after the vaccination, the mice were challenged with a lethal dose of H5N1 influenza virus. The protective efficacy was judged by survival rate, body weight loss and residue virus titer in lungs after the challenge. The results showed that pre-exposure to H1N1 virus could offer mice partial protection against lethal H5N1 challenge and that single-dose injection with NP DNA or NP + M1 DNAs provided significantly improved protection against lethal H5N1 challenge in mice pre-exposed to H1N1 virus, as compared with those in unexposed mice. CONCLUSIONS: Pre-existing immunity against seasonal influenza viruses is useful in offering protection against H5N1 infection. DNA vaccination may be a quick and effective strategy for persons innaive to influenza A virus during H5N1 pandemic.

Comparison of adjuvant efficacy of chitosan and aluminum hydroxide for intraperitoneally administered inactivated influenza H5N1 vaccine.

A safe and effective adjuvant is important to develop vaccines against highly pathogenic avian influenza virus. Chitosan, a derivative from the natural amino polysaccharide chitin, has been proved to be an effective adjuvant for inactivated influenza virus vaccine. In this study, protective immunity in mice provided by chitosan-adjuvanted inactivated H5N1 vaccine was compared with that from an aluminum hydroxide-adjuvanted one. Mice were injected intraperitoneally once or twice with various dosages of inactivated vaccine alone or in combination with an adjuvant (chitosan or aluminum hydroxide). To test the immunization effect, mice were challenged with a lethal dose of H5N1 virus. The results showed that the adjuvanted vaccines were more effective than adjuvant-free ones in inducing humoral immune responses and protecting mice against lethal challenge. Chitosan was comparable to the alum adjuvant in efficacy. These findings indicated that chitosan might be a candidate adjuvant for parenteral administration of inactivated influenza vaccines.