The virologic surveillance offered knowledge of epidemic stereotypes of dengue viruses inViet Nam during the years from 1987-2001. The activity cycle of Dengue-1 stared in 1989 and remained active until 1996. The Dengue-2 activity cycle began in 1987 and continued through 1997. While Dengue-3 first appeared in 1995 and presently continue to be active. Genomic structure of the Dengue-2/Viet Nam/1987 is somewhat different in comparision with several topotypes of the world, but closely related to the Dengue-2 topotype of Jamaica. Another sles relationship has been demonstrated between the Dengue-3/Viet Nam and the Dengue-3/ThaiLand/1987. In Southern Viet Nam, cases of dengue haemorrhagic fever are confirmed through virologic and serologic surveillance in the first quarter of each year
Dengue ; epidemiology

Envelope protein (E) of Dengue virus is an important antigen for immune response of Dengue virus, in which domain 3 (E3) encodes important specific epitopes of each serotype of the virus. It would be of a great value to express domain 3 and apply the recombinant proteins for development of the kit for DF/DHF diagnosis. The domain 3 of the gene coding for the envelope protein of dengue virus type 2 was amplified by PCR with primer pair that hangs BamHI and Xhol restriction sites at the 5 prime of the forward and reverse primer, respectively. The template for domain-3 amplification was the gene encoding preM-E protein that had been cloned and sequenced before. The amplified region of the gene was then inserted into the pET-TRX Fusion Expression Vector System with BamHI and Xhol restriction sites and transformed into E. coli BL21 DE3 Star. Recombinant protein D2E3 was expressed in a fusion form with Thioredoxin and His-Tag after induction with ImM IPTG. Recombinant D2E3 was purified with ProBond Nickel-Chelating Resin column (Invitrogen) and the purified recombinant D2E3 protein was used to check the reaction with the antibodies against native dengue antigens in the patient's sera by ELISA, Western blot and Dot blot. The results showed that, recombinant D2E3 protein of Dengue virus type 2 could react specifically with antibodies in the patient's sera.
Dengue Virus ; Escherichia coli ; Antigens

In the period of 1999 - 2001, there were some outbreaks of dengue fever (DF) and dengue hemorrhagic fever (DHF) in North Vietnam. From 185 blood samples collected from clinically suspected patients at National Institute of Epidemiology, there were 47 positive. By indirect immunofluorescent assay with monoclone antibiotics, 18 samples (38.3%) were identified as dengue virus of type I, 9 samples (19.2%) dengue virus of type II, 20 samples (42.6%) dengue virus of type IV. There was not dengue virus of type III
Dengue ; Dengue Hemorrhagic Fever ; Disease ; epidemiology

The surveillance of Dengue fever/Dengue hemorrhagic fever was conducted in 3 provinces Khanh Hoa, Quang Ngai, Quang Nam (Central Vietnam) during 2000-2002 year period. In terms of serology, virology, an active surveillance network was established involving all health stations, the relating institute, the Department of preventive medicine and MOH, using the standard MAC-ELISA bio-kit of National Institute of Hygien and Epidemiology. No case of the disease was reported, while in surrounding areas, cases were detected. MAC-ELISA kit has had high fidelity, giving quick results
dengue ; Dengue Hemorrhagic Fever ; Diseases ; epidemiology

In the year 2003, 525 specimens seem to be infected with Dengue fever/Dengue haemorrhagic fever in the Northern Vietnam were sent to the National Institute of Hygiene and Epidemiology, those specimens with IgM, IgG antibodies against Dengue virus was 85 cases (16.2%). In 2003, the number of Dengue fever/Dengue haemorrhagic fever was sporadic distributed in some provinces. Owing to active prevention of Dengue fever/Dengue haemorrhagic fever, so Dengue virus type 2 discovered early in Ha Tay, Thanh Hoa, Nghe An and Tay Nguyen provinces; Dengue virus type 1 in Ha Noi, Nghe An, Tay Nguyen provinces and Dengue virus type 4 in Ha Tinh, Thanh Hoa, and Tay Nguyen provinces
Dengue ; epidemiology ; Serology ; Virology

Serum samples from patients with Dengue fever/dengue hemorrhagic fever (DF/DHF) were collected and sent to the Central Institute of Hygiene and Epidemiology in the year 2003. The analysis showed that Dengue virus of type 2 circulated in Ha Tay, Thanh Hoa, Nghe An and Tay Nguyen. In Thanh Hoa, Nghe An, Ha Noi, there were 2 types concurrently and in Tay Nguyen, 3 types of Dengue virus. Results of serological surveillance were reliable because they were detected by provincial laboratories and verified by the Department of Dengue virus of the Central Institute of Hygiene and Epidemiology
Dengue ; epidemiology ; Diseases

In the year 2000, 443 samples of human serum and 131 samples of serum of rodents were assayed by ELISA. Results showed that there were 2.0% of human sera and 2.0% of rodent sera positive with hantaan virus. These preliminary results suggested that Hantaan virus can be the causal factor of hemorrhagic fever in human and in rat
Hantaan virus ; Enzyme-Linked Immunosorbent Assay ; Hemorrhagic Disorders

In 1987-2002 period 1444/9660 samples (14.9%) of Dengue virus were isolated. Type 1 of Dengue virus appeared from 1989 to 1996. type 2 from 1987-1997, type 3 from 1996-1998, and type 4 recently. Gene structure of Viet Nam isolated virus in the year 1987 was similar to those in the world and in Jamaica and type 3 virus in the year 1988 was similar to that of Thailand 1987. The most of human virus isolated from adult were in the North, while in the South mainly at the age of 5-14 (60.28%)
Dengue Virus ; Diseases ; Viruses ; epidemiology

In the year 2003, for Hantaan virus, a serological surveillance ELISA method was performed on 155 serum samples collected from the workers of Haiphong port.26/155 samples were positive or in suspect with rodent sera. The samples submitted to 2nd examen by indirect fluoresceine immuno-assay showed that 3/26 samples were positive 3 positive samples were undertaken further studies by WB technique with specific SEO antigenes ,which confirmed anti-hantaan virus (IgG) and nuclecapsid protein (NP) of51 kD weigt. Results showed that Hantaan virus was found among Haiphong port workers
Hantavirus ; Serum ; Enzyme-Linked Immunosorbent Assay

Serum samples from patients with Dengue hemorrhagic fever were collected at the hospitals of Hanoi,Namdinh,Thanhhoa and NgheAn in 1995-2001 year period were investigated.The number of suspected patients with Dengue hemorrhagic fever was varied during the years, the highest in the year 1995, 1998, then decreased progressively to 2001. In 2 years of 1995-1996 period and 1998-2001 period 4 types of epidemiologic virus were found. The highest number of isolated samples was 54 in the year 1996, then1998. The endemic types varied obviously by years
Dengue ; Epidemiology ; Serum