National Center for Veterinary Diagnosis

Hanoi, Vietnam

National Center for Veterinary Diagnosis

Hanoi, Vietnam
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Cagle C.,U.S. Department of Agriculture | To T.L.,National Center for Veterinary Diagnosis | Nguyen T.,Hanoi University of Agriculture | Wasilenko J.,U.S. Department of Agriculture | And 6 more authors.
Vaccine | Year: 2011

Domestic ducks are key intermediates in the transmission of H5N1 highly pathogenic avian influenza (HPAI) viruses, and therefore are included in vaccination programs to control H5N1 HPAI. Although vaccination has proven effective in protecting ducks against disease, different species of domestic ducks appear to respond differently to vaccination, and shedding of the virus may still occur in clinically healthy vaccinated populations. In this study we compared the response to vaccination between two common domestic duck species, Pekin (Anas platyrhynchos domesticus) and Muscovy (Cairina moschata), which were vaccinated with a commercial inactivated vaccine using one of three different schedules in order to elicit protection to H5N1 HPAI before one month of age. Clear differences in responses to vaccination were observed; the Muscovy ducks developed lower viral antibody titers induced by the same vaccination as Pekin ducks and presented with higher morbidity and mortality after challenge with an H5N1 HPAI virus. When comparing the response to infection in non-vaccinated ducks, differences were also observed, with infected Muscovy ducks presenting a lower mean death time and more severe neurological signs than Pekin ducks. However Pekin ducks had significantly higher body temperatures and higher levels of nitric oxide in the blood at 2 days post challenge than Muscovy ducks, indicating possible differences in innate immune responses. Comparison of the expression of innate immune related genes in spleens of the non-vaccinated infected ducks showed differences including significantly higher levels of expression of RIG-I in Pekin ducks and of IL-6 in Muscovy ducks. Both duck species showed an up-regulation of IFNα and MHC-I expression, and a down-regulation of MHC-II. In conclusion, differences in response to infection and vaccination were observed between the two domestic duck species. This information should be taken into account when developing effective vaccination programs for controlling H5N1 HPAI in different species of ducks. © 2011.

Cagle C.,U.S. Department of Agriculture | Wasilenko J.,U.S. Department of Agriculture | Adams S.C.,University of California at Davis | Cardona C.J.,University of Minnesota | And 8 more authors.
Avian Diseases | Year: 2012

In a previous study, we found clear differences in pathogenicity and response to vaccination against H5N1 highly pathogenic avian influenza (HPAI; HA clade 2.3.4) between Pekin (Anas platyrhynchos var. domestica) and Muscovy (Cairina moschata) ducks vaccinated using a commercial inactivated vaccine (Re-1). The objective of the present study was to further investigate the pathogenicity of H5N1 HPAI viruses in different species of ducks by examining clinical signs and innate immune responses to infection with a different strain of H5N1 HPAI virus (HA clade 1) in two domestic ducks, Pekin and Muscovy, and one wild-type duck, mallard (Anas platyrhynchos). Protection conferred by vaccination using the Re-1 vaccine against infection with this virus was also compared between Pekin and Muscovy ducks. Differences in pathogenicity were observed among the virus-infected ducks, as the Muscovy ducks died 2 days earlier than did the Pekin and mallard ducks, and they presented more-severe neurologic signs. Conversely, the Pekin and mallard ducks had significantly higher body temperatures at 2 days postinfection (dpi) than did the Muscovy ducks, indicating possible differences in innate immune responses. However, similar expression of innate immune-related genes was found in the spleens of virus-infected ducks at this time point. In all three duck species, there was up-regulation of IFN-, IFN-, IL-6, CCL19, RIG-I, and MHC class I and down-regulation of MHC class II, but variable expression of IL-18 and TLR7. As in our previous study, vaccinated Muscovy ducks showed less protection against virus infection than did Pekin ducks, as evidenced by the higher mortality and higher number of Muscovy ducks shedding virus when compared to Pekin ducks. In conclusion, infection with an H5N1 HPAI virus produced a systemic infection with high mortality in all three duck species; however, the disease was more severe in Muscovy ducks, which also had a poor response to vaccination. The differences in response to virus infection could not be explained by differences in the innate immune responses between the different types of ducks when examined at 2 days dpi, and earlier time points need to be evaluated. © American Association of Avian Pathologists.

Pfeiffer D.U.,Lane College | Otte M.J.,Animal Production and Health Division | Roland-Holst D.,University of California at Berkeley | Inui K.,National Center for Veterinary Diagnosis | And 2 more authors.
Veterinary Journal | Year: 2011

This paper analyses the publicly available data on the distribution and evolution of highly pathogenic avian influenza virus (HPAIV) H5N1 clades, whilst acknowledging the biases resulting from the non-random selection of isolates for gene sequencing. The data indicate molecular heterogeneity in the global distribution of HPAIV H5N1, in particular in different parts of East and Southeast Asia. Analysis of the temporal pattern of haemagglutinin clade data shows a progression from clade 0 (the 'dominant' clade between 1996 and 2002) to clade 1 (2003-2005) and then to clade 2.3.4 (2005 onwards). This process continuously produces variants, depending on the frequency of virus multiplication in the host population, which is influenced by geographical variation in poultry density, poultry production systems and also HPAI risk management measures such as vaccination. Increased multilateral collaboration needs to focus on developing enhanced disease surveillance and control targeted at evolutionary 'hotspots'. © 2010 Elsevier Ltd.

Cha R.M.,U.S. Department of Agriculture | Smith D.,U.S. Department of Agriculture | Shepherd E.,U.S. Department of Agriculture | Davis C.T.,Centers for Disease Control and Prevention | And 8 more authors.
Vaccine | Year: 2013

Domestic ducks are the second most abundant poultry species in many Asian countries including Vietnam, and play a critical role in the epizootiology of H5N1 highly pathogenic avian influenza (HPAI) [FAO]. In this study, we examined the protective efficacy in ducks of two commercial H5N1 vaccines widely used in Vietnam; Re-1 containing A/goose/Guangdong/1/1996 hemagglutinin (HA) clade 0 antigens, and Re-5 containing A/duck/Anhui/1/2006 HA clade 2.3.4 antigens. Ducks received two doses of either vaccine at 7 and at 14 or 21 days of age followed by challenge at 30 days of age with viruses belonging to the HA clades 1.1,, and isolated between 2008 and 2011 in Vietnam. Ducks vaccinated with the Re-1 vaccine were protected after infection with the two H5N1 HPAI viruses isolated in 2008 (HA clades 1.1 and showing no mortality and limited virus shedding. The Re-1 and Re-5 vaccines conferred 90-100% protection against mortality after challenge with the 2010 H5N1 HPAI viruses (HA clade; but vaccinated ducks shed virus for more than 7 days after challenge. Similarly, the Re-1 and Re-5 vaccines only showed partial protection against the 2011 H5N1 HPAI viruses (HA clade and, with a high proportion of vaccinated ducks shedding virus for more than 10 days. Furthermore, 50% mortality was observed in ducks vaccinated with Re-1 and challenged with the virus. The HA proteins of the 2011 challenge viruses had the greatest number of amino acid differences from the two vaccines as compared to the viruses from 2008 and 2009, which correlates with the lesser protection observed with these viruses. These studies demonstrate the suboptimal protection conferred by the Re-1 and Re-5 commercial vaccines in ducks against H5N1 HPAI clade viruses, and underscore the importance of monitoring vaccine efficacy in the control of H5N1 HPAI in ducks. © 2013 .

PubMed | Chulalongkorn University, Mahasarakham University, National Center for Veterinary Diagnosis and National Science and Technology Development Agency
Type: Journal Article | Journal: Transboundary and emerging diseases | Year: 2016

Porcine deltacoronavirus (PDCoV) was detected by RT-PCR in 12 of 97 (12.4%) intestinal samples collected during 2015 from piglets with diarrhoea in Thailand, Vietnam and Lao PDR. Spike, membrane and nucleocapsid genes were characterized, and phylogenetic analyses demonstrated that PDCoV isolates from Thai and Lao PDR form a novel cluster, separated from US and China isolates, but relatively were more closely related to China PDCoV than US isolates. Vietnam PDCoVs, however, were grouped together with US PDCoV. The analyses of amino acid changes suggested that they were from different lineage.

van de N.,Hanoi Medical University | Trung N.V.,National Hospital of Tropical Diseases | Ha N.H.,National Hospital of Tropical Diseases | Nga V.T.,National Center for Veterinary Diagnosis | And 4 more authors.
Korean Journal of Parasitology | Year: 2012

The 5th outbreak of trichinosis occurred in a mountainous area of North Vietnam in 2012, involving 24 patients among 27 people who consumed raw pork together. Six of these patients visited several hospitals in Hanoi for treatment. Similar clinical symptoms appeared in these patients within 5-8 days after eating infected raw pork, which consisted of fever, muscle pain, difficult moving, edema, difficult swallowing, and difficult breathing. ELISA revealed all (6/6) positive reactions against Trichinella spiralis antigen and all cases showed positive biopsy results for Trichinella sp. larvae in the muscle. The larvae detected in the patients were identified as T. spiralis (Vietnamese strain) by the molecular analysis of the mitochondrial cytochrome c oxidase subunit III (cox3) gene. © 2012, Korean Society for Parasitology and Tropical Medicine.

Slomka M.J.,Animal Health and Veterinary Laboratories Agency AHVLA Weybridge | To T.L.,National Center for Veterinary Diagnosis | Tong H.H.,National Center for Veterinary Diagnosis | Coward V.J.,Animal Health and Veterinary Laboratories Agency AHVLA Weybridge | And 3 more authors.
Influenza and other Respiratory Viruses | Year: 2012

Background Evaluation of two commercial lateral flow devices (LFDs) for avian influenza (AI) detection in H5N1 highly pathogenic AI infected poultry in Vietnam. Objectives Determine sensitivity and specificity of the LFDs relative to a validated highly sensitive H5 RRT PCR. Methods Swabs (cloacal and tracheal) and feathers were collected from 46 chickens and 48 ducks (282 clinical specimens) and tested by both LFDs and H5 RRT PCR. A subset of 59 chicken and 34 duck specimens was also tested by virus isolation (VI), the 'gold standard'. Results Twenty-six chickens and 15 ducks were shown to be infected by at least one RRT PCR positive clinical specimen per bird. Bird-level sensitivity for the Anigen LFD was 84·6% for chickens and 53·3% for ducks, and for the Quickvue LFD 65·4% for chickens and 33·3% for ducks. Comparison of the three clinical specimens revealed that chicken feathers were the most sensitive with 84% and 56% sensitivities for Anigen and Quickvue respectively. All 21 RRT PCR positive swabs from ducks were negative by both LFDs. However, duck feather testing gave sensitivities of 53·3% and 33·3% for Anigen and Quickvue respectively. Specificity was 100% for both LFDs in all investigations. Conclusions Although LFDs were less sensitive than AI RRT PCR and VI, high titre viral shedding in H5N1 highly pathogenic avian influenza (HPAI) infected and diseased chickens is sufficient for a proportion of birds to be identified as AI infected by LFDs. Feathers were the optimal specimen for LFD testing in such diseased HPAI scenarios, particularly for ducks where swab testing by LFDs failed to identify any infected birds. However, specimens should be forwarded to the laboratory for confirmation by more sensitive diagnostic techniques. © 2011 Blackwell Publishing Ltd.

Pfeiffer J.,U.S. Department of Agriculture | Suarez D.L.,U.S. Department of Agriculture | Sarmento L.,U.S. Department of Agriculture | To T.L.,National Center for Veterinary Diagnosis | And 2 more authors.
Avian Diseases | Year: 2010

Highly pathogenic (HP) H5N1 avian influenza (AI) viruses continue to circulate in Asia and have spread to other regions of the world. Though attempts at eradication of the viruses during various outbreaks have been successful for short periods of time, new strains of H5N1 viruses continue to emerge and have become endemic in parts of Asia and Africa. Vaccination has been employed in Vietnam as part of AI control programs. Domestic ducks, which make up a large part of poultry in Vietnam, have been recognized as one of the primary factors in the spread of AI in this country. As a result, ducks have been included in the vaccination programs. Despite the effort to control AI in Vietnam, eradication of the disease has not been possible, due in part to the emergence and spread of new viruses. Here, we tested the abilities of avian influenza oil emulsion vaccines of different genetic origins to protect against disease and viral shedding in both 2-wk-old white leghorn chickens and 1-wk-old Pekin ducks. Seventy-five to 100% of vaccinated chickens were protected from mortality, but viral shedding occurred for at least 4 days post challenge. All but one vaccinated duck were protected from mortality; however, all groups shed virus up through at least 5 days postchallenge, depending on the vaccine and challenge virus used. Differences in levels of hemagglutination inhibition (HI) antibody titers induced by the vaccines were observed in both chickens and ducks. Although the vaccines tested were effective in protecting against disease and mortality, updated and more efficacious vaccines are likely needed to maintain optimal protection. © 2010 American Association of Avian Pathologists.

PubMed | Institute of Tropical Medicine and National Center for Veterinary Diagnosis
Type: | Journal: Veterinary parasitology | Year: 2016

Taenia hydatigena, a non-zoonotic tapeworm species shares the same intermediate hosts with other Taenia zoonotic species, such as Taenia solium in pigs and Taenia saginata in cattle. The occurrence of T. hydatigena in pigs and cattle may cause cross-reactions in immunodiagnostic tests and therefore, complicate the diagnosis of the zoonotic species. This study was conducted to systematically review the data on the prevalence of T. hydatigena in pigs and cattle, with the aim to assess the potential interference in serological diagnosis of zoonotic Taenia spp. due to T. hydatigena infection. We searched PubMed, Web of Science, Africa Journal Online, website and article reference lists in English, French and Vietnamese with no restriction on research time and publication status. Eligible studies included observational studies that showed the occurrence of T. hydatigena. Twenty-six studies, divided into two animal groups, i.e. pigs and cattle, met the eligibility criteria for qualitative synthesis and 17 studies were included for the meta-analysis in three continents. T. hydatigena was found by necropsy in all included studies, which mostly were abattoir surveys. Overall, results showed the worldwide occurrence of T. hydatigena cysticercosis in pigs and cattle. In pigs, there was a marked higher prevalence in Asia and South America that was 17.2% (95% CI: 10.6-26.8%) and 27.5% (CI: 20.8-35.3%), respectively, compared to a low prevalence of 3.9% (95% CI: 1.9-7.9%) in Africa. Overall, the prevalence of T. hydatigena in cattle was low with a mean of 1.1% (95% CI: 0.2-5.2%). These results show that interpretation of results of sero-diagnostic tests for zoonotic Taenia species in pigs and cattle has to take into account the prevalence of T. hydatigena infections in different settings.

Oanh T.K.N.,Bioscience Technology | Oanh T.K.N.,National Center for Veterinary Diagnosis | Nguyen V.K.,National Institute of Veterinary Research | De Greve H.,Vrije Universiteit Brussel | Goddeeris B.M.,Bioscience Technology
Infection and Immunity | Year: 2012

Edema disease (ED) in piglets is caused by Shiga toxin Stx2e-producing Escherichia coli. We show that a genetically disarmed Stx2e toxoid is a safe antigen that generates antiserum protecting piglets against the Stx2e toxin. Immunization of suckling piglets with the Stx2e toxoid was safe, had no adverse effects on growth of the piglets, and resulted in effective prevention of edema disease clinical symptoms after challenge with the Stx2e toxin. Our data showed that maternal immunity against the Stx2e toxoid can be transmitted from the vaccinated sows to the piglets via the colostrum. Very high levels of Stx2e-specific serum antibodies persisted in these piglets until 1 month postweaning, bridging the critical period in which the weaned piglets are most susceptible to edema infection. Challenge with Stx2e toxin resulted in clinical signs of edema disease and death of all control piglets from nonimmunized sows, whereas none of the piglets from immunized sows developed clinical signs of ED. © 2012, American Society for Microbiology.

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