Tehran University Medical Journal

Background: Acute respiratory tract infections, both bacterial and viral, cause 4.5 million childhood deaths worldwide, most of which occur in developing countries. Parainfluenza viruses, of the paramyxoviridae family, are among the common causes of acute respiratory infections, giving rise to 30% of respiratory infections in children before school age. The four parainfluenza viruses that cause a spectrum of respiratory illness in humans are designated as human para influenza virus-1 through 4. Spreading from the respiratory tract by aerosolized secretions or direct hand contact with secretions, parainfluenza viruses replicate in the respiratory epithelium without evidence of systemic spread. The destruction of cells in the upper airways can lead to secondary bacterial invasion and resultant bacterial tracheitis. Eustachian tube obstruction can lead to secondary bacterial invasion of the middle ear space and acute otitis media. In otherwise healthy children, the majority of illnesses remain in the upper respiratory tract. As with many viruses, three approaches to the diagnosis of parainfluenza virus are currently used: viral culture, detection of viral antigen or nucleic acid, and serologic analysis. The gold standard remains the isolation of virus in tissue culture.

Methods: This descriptive case-series study was conducted from January 2003 to January 2004, and included 96 children five years of age and younger. To determine the relative frequency of parainfluenza respiratory tract infection, the nasopharyngeal secretions were studied by immunofluorescent antibody (IFA) assay. Seasonal incidence, age distribution and clinical signs and symptoms of this infection were also recorded.

Results: Among our study group, the relative frequency of parainfluenza respiratory infection was 26%, most commonly in children aged 25-36 months and in autumn. Cough (84%) and rhinorrhea (96%) were the most common symptoms, with fever (68%) as the most common sign in our patients. Pharyngotonsilitis was the most common (40%) clinical manifestation in our patients.

Conclusions: According to above data, patient age and the frequency of parainfluenza infection were similar to other studies.

The spread of influenza viruses in multiple bird and mammalian species is a worldwide serious threat to human and animal populations' health and raise major concern for ongoing pandemic in humans. Direct transmission of the avian viruses which have sialic acid specific receptors similar to human influenza viruses are a warning to the emergence of a new mutant strain that is likely to share molecular determinants to facilitate their replication in human host. So the emerge virus can be transmitted easily through person to person. The genetic variations of the influenza viruses, emerge and re-emerge of new antigenic variants, and transmission of avian influenza viruses to human may raise wide threat to public health and control of pandemic influenza. Vaccination, chemoprophylaxis with specific antiviral drugs, and personal protective non-pharmacological measures are tools to treat influenza virus infection. The emergence of drug resistant strains of influenza viruses under drug selective pressure and their limited efficacy in severe cases of influenza infections highlight the need to development of new therapies with alternative modes. In recent years several studies have been progressed to introduce components to be act at different stages of the viral life cycle with broad spectrum reactivity against mammalian and bird influenza subtypes. A wide variety of different antiviral strategies include inhibition of virus entry, blocking of viral replication or targeting of cellular signaling pathways have been explored. The current inactivated influenza vaccines are eliciting only B-cell responses. Application of the vaccines has been limited due to the emergence of the new virus antigenic variants. In recent decade development of gene vaccines by targeting various influenza virus proteins have been interested because significant potential for induction of both humoral and cell mediated immunity responses. Enhanced and directed immune responses to viral vaccine can be achieved by using adjuvant. The ability of biological molecular adjuvant such as cytokines, interlukines, and bacterial derivatives to improve the immunogenicity of vaccines as a novel strategy is under evaluation, however, and immune system regulator proteins have additional considerations.

Background: The influenza virus is one of the most important factors for higher morbidity and mortality in the world. Recently, researchers have been focused on influenza conserved antigenic proteins such as hemagglutinin stalk domain (HA2) for vaccine production and serological studies. The HA2 plays a major role in the fusion of the virus with host cells membrane. The immunity system enables to produce antibody against HA2. The aim of this study is polyclonal antibody production against influenza HA2. Methods: This study was done in the Influenza Research Lab, Pasteur Institute of Iran, Tehran for one year from September 2013 to October 2014. In the present study, recombinant HA2 protein was produced in prokaryotic system and purified using Nickel affinity chromatography. The purified HA2 was mixed with Freund’s adjuvant (complete and incomplete) and injected into two New Zealand white rabbits by intramuscularly and subcutaneously routes. Immunization was continued for several months with two weeks interval. Before each immunization, blood was drawn by venous puncture from the rabbit ear. Function of rabbit's sera was evaluated using radial immunodiffusion (RID) in both forms, Single RID (SRID) and Double RID (DRID). Finally, antiserum activity against HA2 was evaluated using western blotting as serological assay. Results: Sedimentary line and zone was observed in RID assays (SRID and DRID) represent interaction between HA2 protein and anti- HA2 antibody. As well as, western blotting results was positive for HA2 protein. Therefore, these results showed that polyclonal antibody produced against HA2 protein can identify HA2 protein antigenic sites. Conclusion: These findings show that humoral immune responses have properly been stimulated in rabbits and these antibodies can identify HA2 protein and may be suitable for other serological methods.

Background: Problems of live and inactivated influenza vaccines such as, increasing emerge and re-emerge viruses with high human mortality, current epidemics of influenza and direct transmission of avian viruses to human, affect the vaccination program. DNA vaccines as third generation of vaccines is specially considered for control of influenza in human and poultry. The main advantage of these vaccines is humoral and cellular immune responses and broad spectrum of using these vaccines for control of circulating strains of influenza. In this study the conserved fragment of HA2 to form of DNA vaccine was designed to induce immunity against influenza viruses and its heterologous protective immunity against these viruses was evaluated.