Background Nha Trang Institute of Vaccines Medical Biologicals has produced successfully vaccine for human influenza A/H5N1 in embryonic chicken eggs. Effectiveness of the vaccine immune response is highly dependent on the type of adjuvant used.\r\n', u'Objective: To study adjuvants for preparing A/H5N1 influenza vaccine.\r\n', u'Subjects and methods: The study used a comparative approach on capacity to increase the immune response of various adjuvants AIPO4, Chitosan and Freund tested in mice. Experiment of erythrocyte agglutination reaction is used to measure levels of antibody response in mice blood. The process of weight gain in mice after injection of vaccine adjuvant mixture is monitored.\r\n', u'Results: HA antibody level of the vaccine adjuvant mixture is higher than of the vaccine without adjuvant. Capacity of stimulating immune response of Chitosan adjuvant is higher than AlPO4. Repeat injection on day 20th is suitable for vaccine with AlPO4or vaccine without adjuvant. Repeat injection is after day 20th for vaccine with Chitosan or Freund depending on the amount of residual antibody in the blood. \r\n', u'Capacity of stimulating immune response of Freund adjuvant is the best in the 3 adjuvants but the safety of this adjuvant is low\r\n', u' Freund adjuvant should be used only for animals. When using Freund adjuvant to induce immunity to animals it should determine the amount of antibodies causing immune before repeating.\r\n', u'Conclusion: Freund adjuvant should be used only for animals. \r\n', u'\r\n', u'
Influenza A Virus ; H5N1 Subtype

Genomes of 24 human and avian H5N1 influenza viral strains in the Southern area of Vietnam during the 2004-2005 outbreaks were sequenced completely. All viruses containing multiple basic amino acids at the hemagglutinin cleavage site HA1-HA2 are associated with a highly pathogenic phenotype. A series of amino acid mutations located in NSl and PB2 proteins were associated with the possibility of efficient replication in mammalian tissue. The mutation in the receptor binding sites of HA that could affect binding process to human cells was found from isolates in 2004-2005 Avianflu outbreaks. All isolates are belonging to Z genotype. The findings indicated that H5Nl viruses in Vietnam have changed to be more infectious to human host in 2004-2005 Avianflu outbreaks.
Influenza A Virus, H5N1 Subtype ; Humans

Rapid identification of influenza A virus (H5N1) is very important for endemic control and prevention. RT-PCR method proved good rapidity. The sensitivity and the specificity is needed to be improved with complete design of primer pairs.
Influenza A Virus, H5N1 Subtype ; Diagnosis

At the end of 2003 and early 2004, an epidemic of avian influenza with 10 cases and 7 deaths occurred in the North of Vietnam, a subtype H5N1 (A/H5N1) has been identified. The prevalence of total infection with epidemic syndrome in the whole area at the same time was 0.1%, the prevalence infected cases of death was very high (70%). The epidemic was widely distributed in 7 provinces and the highest number of cases was observed in the forth week by the onset of the first case. Sick hens were the evidence of causes. There was not direct infection from human to human. However, there were two case-clusters that happened in the same family, this may be a suggestion of biological and familial factors associated with the susceptibility to the causal virus A/H5N1
Epidemiology ; Influenza A Virus ; H5N1 Subtype ; Influenza in Birds

Epidemic of influenza A H5 N1 virus in humans occurred in South Vietnam from 12/2003 up to now there were 287 suspected cases and 24 confirmed cases, included 20 deaths with case-fatality rate was very high (83.33%). Based on epidemical surveillance and laboratory, we believed that cases usually appear by the end of year and the beginning of the next year at the same time of the winter in North Vietnam, and the dry season in the South Vietnam. It was distributed sporadically in different regions, including highland, urban areas and rural areas of the Mekong delta. Almost of the confirmed cases were young (average 16,17 years old). The rate of ethnic patients with H5N1(+) were high 25%. There has been no evidence of human to human transmission, but there were some risk factors associated with the confirmed cases were: contact directly with the sick/dead poultry (OR=3.39; p=0.034), eating the sick/dead poultry (OR=4.28; p= 0.025), person in family prepared chicken that was sick and died for cooking (OR=5.2; p=0.01).
Influenza A Virus, H5N1 Subtype ; Viruses ; Epidemiology

Study on clinical features and epidemiology among 10 patients had avian influenza A who treated in hospital in Ho Chi Minh City and Ha Noi 12/2003 and 1/2004, 13,7 mean age. In all patients, the diagnosis of influenza A (H5N1) was confirmed by means of viral culture or reverse transcriptase polymerase chain reaction (RT-PCR) with primers specific for H5 and N1. None of the 10 patients had pre-existing medical conditions. Nine patients had a clear history of direct contact with poultry. All patients had fever, respiratory symptoms and clinically significant lymphopenia. The medium platelet count was 75.500/mm3. Seven patients had diarrhea. In all patients, there were marked abnormalities on chest radiography. There was no definitive evidence of human to human transmission, eight patients died
Influenza A Virus, H5N1 Subtype ; Influenza in Birds ; epidemiology

The occasional influenza pandemics and the seasonal influenza epidemics have destroyed millions of lives since the last century. It is therefore necessary to understand the virus replication patterns as this provides essential information on the virus infectivity, pathogenicity and spread patterns. This study aimed to investigate the replication of avian influenza A virus H5N1 (A/Chicken/Malaysia/5858/2004) in MDCK cells. In this study, the TCID50 (50% tissue culture infectious dose) of AIV H5N1 was first determined. The MDCK cells were then infected with AIV H5N1 at TCID50 for 0-48 h. The CPE (cytopathic effect) was observed and cell death was determined hourly. The virus-infected cells and media were subsequently collected for gene analysis. The results showed that the TCID50 of AIV H5N1 was 10-9 dilution. The CPE percentage showed a strong and positive correlation with the infection period (r = 1.0, n = 9, p < 0.01). The amount of a highly conserved influenza viral gene, M2 gene amplified from infected media (r = 0.471, n = 9, p= > 0.05) and infected cell (r = 0.73, n = 9, p < 0.05) were also positively correlated with the infection period. In conclusion, although CPE started to be observed in the early time points of infection, however, the M2 gene was only amplified from the infected media and cells after 48 h and 24 h, respectively. This signifies that AIV H5N1 used in this study is pathogenic and it is able to cause severe cytopathology to host cells even at low virus load.
Influenza, Human ; Influenza A Virus, H5N1 Subtype

Animals ; Humans ; Influenza A Virus, H5N1 Subtype ; immunology ; pathogenicity ; Poultry ; virology

Background: A/H5N1 influenza virus spreads from birds to humans and cause influenza diseases with high mortality rate. Vaccination is the most effective way to protect communities from pandemic, reduce morbidity and mortality. The study of creating A/H5N1 influenza vaccines in conformity with Vietnam was the urgent need. Institute of Vaccine\u2019s Achievement (IVAC) studied production of inactivated influenza vaccine for human on egg-grown from reassortants NIBRG-14. Objectives: In order to produce experimentally A/H5N1 influenza vaccine for human in accordance with WHO requirements and set up a viable process for production of the vaccines. Subjects and method: 10 days embryonated eggs and NIBRG-14 strains were served to the study with LAL method to check endotoxin, Kijehdal method to test total protein. Results: IVAC had produced successfully 5 lots of absorbed vaccine A/H5N1 (FLUVAC) using NIBRG-14 strains and embryonated eggs. Initially, production and quality control processes had been set up at IVAC by applying the recommendations of WHO. Conclusion: The success of the study was a basis of the approval of the government to establish a influenza vaccine manufacturing facilities.
Influenza A Virus ; H5N1 Subtype ; Influenza Vaccines ; Humans ; Eggs

We conducted a matched case-control study with 28 laboratory-confirmed cases of influenza A/H5N1 (by RT-PCR assay) and 106 controls in Vietnam in the year 2004 (case to control ratio is 1:4). Matching criteria includes sex, age (the difference is less than 2 year) and location of living. Main results are as follow: (1) Two poultry-related risk factors of human avian influenza A/H5N1 are direct handling of ill/dead poultry, and having ill/dead poultry in household. (2) Unavaillable indoor water-tap in household is signifficantly associated with human influenza A/H5N1. This is an suggestion to the role of hygiene and invironment-related factors, but the mechanism is still not clear. (3) Exposure to healthy poultry, domestic animals and patients with acute respiratory infections seems not to be a risk factor for avian influenza infection in the year 2004. Further studies with integrated designs are needed to describe mode(s) of transmission and identify sources of infection.
Influenza A Virus, H5N1 Subtype ; Humans, Vietnam ; Risk factors