Suppressive Effects of Chronic Stress on Influenza Virus Protection after Vaccination with Plasmid DNA-Encoded Nucleoprotein.

BACKGROUND: Influenza is a highly infectious and acute respiratory disease caused by an infection of the host respiratory tract mucosa by the influenza virus. The use of DNA vaccines that express conserved genes such as nucleoprotein (NP) represents a new method of vaccination against influenza. In this study, the effect of chronic stress on the efficiency of this type of vaccine has been evaluated in a mouse model. METHODS: The NP DNA vaccine was administered intradermally 3 times on days 0, 3 and 6 to stressed and nonstressed male BALB/c mice. Two weeks after the last immunization, half of these mice were challenged with A/Puerto Rico/8/34 (PR8) influenza virus and were weighed for 12 days, and their mortality rate was assessed during this period. The cellular immune response of the other half of the mice was evaluated by cytotoxicity assay. RESULTS: The results indicate a significant reduction in the cytotoxic T-lymphocyte response of stressed mice in comparison with unstressed mice. Also, the percentage of weight loss and mortality after the challenge in stressed mice was significantly increased compared to the other group. CONCLUSION: These results indicate that the NP DNA vaccine is not able to induce any effective cytotoxic T-lymphocyte response against influenza virus in stressed mice and cannot induce protective immunity against influenza infection in this group of mice.

Molecular epidemiology of human respiratory syncytial virus (HRSV) in Iranian military trainees with acute respiratory symptoms in 2017.

BACKGROUND AND OBJECTIVES: Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infection in many populations, including military recruits receiving basic training. Therefore, this study was set out to determine the molecular epidemiology, genotype and phylogenetic features of RSVs in patients with respiratory infection as a case study. MATERIALS AND METHODS: In this study, military barracks of Tehran, Iran, between January to March 2017 exposed to respiratory diseases were used for sampling. Throat swabs were taken, a reverse transcriptase-polymerase chain reaction (RTPCR) assay was performed to identify RSV and then the genotyping and phylogenetic analyses of RSVs in patients with a respiratory infection. RESULTS: Among 400 Iranian military trainees with respiratory symptoms, RSV infection was identified in 2.75% (11/400) using RT-PCR. Sequencing showed the incidence of type A (2.5%, n=10) to be much higher than type B (0.25%, n=1); Sore throat was the most common symptom among RSV patients. Phylogenetic analysis revealed that the majority of strains from the studied samples were more consistent with those from the Philippines and the US strains. CONCLUSION: This study is the first to document RSV as a major cause of acute respiratory illness among military trainees in Iran. The prevalence of RSV is substantial in the cold season and the prevalence of genotype A is dominant in the country, leading to take essential steps in preparing a preventive vaccine against this viral infection.

Reconstruction of H3N2 influenza virus based virosome in-vitro.

BACKGROUND AND OBJECTIVES: Virosomes are Virus Like Particles (VLP) assembled in-vitro. Influenza virosomes maintain the cell binding and membrane fusion activity of the wild type virus but are devoid of viral genetic material or internal proteins. Influenza virosomes mimic the natural antigen presentation route of the influenza virus. METHODS: Virosomes were prepared by membrane solubilization and reconstitution. Briefly, the Madine-Darby Canine kidney (MDCK) cell line was cultivated on microcarrier beads inoculated with influenza virus strain A/X-47 (H3N2). The culture medium was harvested and clarified. Subsequently, virus was concentrated and purified by ultrafiltration and ultracentrifugation. The purified viral membrane was dissolved by adding 375 µl of 200 mM 1, 2-dicaproyl-sn-glycero-3-phosphocholine (DCPC) in HEPES-buffered saline (HBS). Nucleocapsid was removed by ultracentrifugation. The supernatant consisting of phospholipids and glycoproteins of the influenza virus was reconstituted by removal of DCPC using overnight dialysis against Hank's Buffered Saline (HBS) solution at 4°C. After dialysis, crude virosome preparation was layered over a discontinuous sucrose gradient in order to separate non-incorporated material from the reconstituted virus membranes. RESULTS: The virosome harvested from the boundary of the two sucrose layers successfully was identified by the Hemagglutination assay and western blotting. CONCLUSION: Use of a dialyzable short-chain phospholipid (DCPC) is an efficient procedure for solubilization and reconstitution of influenza virus virosomes and has not caused structural changes in a major envelope glycoprotein (hemagglutinin protein) on the surface of virosome.