Yong Poovorawan

Avian influenza H5N1 in tigers and leopards.

Influenza virus is not known to affect wild felids. We demonstrate that avian influenza A (H5N1) virus caused severe pneumonia in tigers and leopards that fed on infected poultry carcasses. This finding extends the host range of influenza virus and has implications for influenza virus epidemiology and wildlife conservation.

Fatal avian influenza A H5N1 in a dog.

Avian influenza H5N1 virus is known to cross the species barrier and infect humans and felines. We report a fatal H5N1 infection in a dog following ingestion of an H5N1-infected duck during an outbreak in Thailand in 2004. With new reports of H5N1 virus continuing across Asia, Europe, and Africa, this finding highlights the need for monitoring of domestic animals during outbreaks.

Avian Influenza H5N1 in Naturally Infected Domestic Cat

We report H5N1 virus infection in a domestic cat infected by eating a pigeon carcass. The virus isolated from the pigeon and the cat showed the same cluster as the viruses obtained during the outbreak in Thailand. Since cats are common house pets, concern regarding disease transmission to humans exists.

Probable tiger-to-tiger transmission of avian influenza H5N1.

During the second outbreak of avian influenza H5N1 in Thailand, probable horizontal transmission among tigers was demonstrated in the tiger zoo. Sequencing and phylogenetic analysis of those viruses showed no differences from the first isolate obtained in January 2004. This finding has implications for influenza virus epidemiology and pathogenicity in mammals.

Clinical Characteristics and Prognosis of Hepatocellular Carcinoma Analysis Based on Serum Alpha-fetoprotein Levels

The purpose of this study was to determine whether a relation does exist between clinicopathologic features and the prognosis of hepatocellular carcinoma (HCC) with respect to serum alpha-fetoprotein (AFP) levels at diagnosis. We reviewed the clinical data of 309 pathologically proven HCC cases divided into three groups: group 1 with normal AFP (<20 IU/mL), group 2 with moderately elevated AFP (20–399 IU/mL) and group 3 with markedly elevated AFP (≥400 IU/mL). Of these, there were 76 (24.6%), 78 (25.2%), and 155 patients (50.2%) in groups 1, 2, and 3, respectively. We found that HCC patients with high AFP tended to have greater tumor size, bilobar involvement, massive or diffuse types, and portal vein thrombosis. Nonetheless, we could not establish a correlation between increased AFP and Okudas stages, degree of tumor differentiation, or extrahepatic metastasis. The median survival rates in groups 1 (6 months) and 2 (7 months) were significantly longer than that of group 3 (3 months). On multivariate logistic regression analysis, positive hepatitis B surface antigen (HBsAg) status and bilobar tumor involvement represented the independent factors for predicting high AFP values. We concluded that AFP is useful not only for diagnosis, but also as a prognostic indicator in patients with HCC . However, it cannot be considered a sensitive tumor marker, particularly during the early stages in HBsAg-negative patients.

Identification of a Naturally Occurring Recombinant Genotype 2/6 Hepatitis C Virus

ABSTRACT Hepatitis C viruses (HCVs) display a high level of sequence diversity and are currently classified into six genotypes and an increasing number of subtypes. Most likely, this heterogeneity is caused by genetic drift; evidence for recombination is scarce. To study the molecular heterogeneity of HCV in Vietnam, we analyzed 58 HCV RNA-positive sera from Vietnamese blood donors by sequence analysis of the CORE and NS5B regions. Phylogenetic analyses revealed the presence of genotype 1 (38%), genotype 2 (10.3%), and genotype 6 viruses (51.7%). All samples showed concordant results except for two (D3 and D54). Sample D54 was a mixed infection of genotype 2i and 6h viruses. Whole-genome analysis and bootscan analysis of sample D3, on the other hand, revealed a recombinant virus with genotype 2i and genotype 6p sequences at the 5′ and 3′ ends, respectively. The crossover point was located between nucleotide positions 3405 to 3464 (numbering according to prototype strain HCV-H, M67463) at the NS2/NS3 junction. The identification of this naturally occurring recombinant virus strengthens the concept that recombination may play a role in HCV epidemiology and evolution. Furthermore, the location of the recombination breakpoint may be relevant for constructing infectious chimeric viruses.

High prevalence of human rhinovirus C infection in Thai children with acute lower respiratory tract disease

Summary Objective To determine the prevalence of human rhinoviruses (HRV) infections in children with lower respiratory disease in Thailand and monitor the association between species of HRV and clinical presentation in hospitalized paediatric patients. Method Two hundred and eighty-nine nasopharyngeal (NP) suction specimens were collected from hospitalized paediatric patients admitted to King Chulalongkorn Memorial Hospital, Thailand during February 2006–2007. Nucleic acids were extracted from each sample with subsequent amplification of VP4/2 by semi-nested RT-PCR for HRV detection. Other viral respiratory pathogens were also detected by PCR, RT-PCR or real time PCR. Nucleotide sequences of the VP4 region were used for genotyping and phylogenetic tree construction. Result In total, 87 of 289 specimens were positive for HRV indicating an annual prevalence of 30%. Wheezing or asthma exacerbation was the most common clinical presentation observed in infected patients. Sequence analysis and phylogenetic tree showed that 29 (33%) and 8 (9%) specimens belonged to HRV-A and HRV-B, respectively. Most of the HRV positive samples were HRV-C (58%). Moreover, species C was predominantly found in the paediatric population of Thailand in raining season (p <0.05). The frequency of co-infection of HRV-C with other respiratory viral pathogens was approximately 40%. Conclusion HRV-C represents the predominant species and is one of the etiologic agents in acute lower respiratory tract infection, causes of wheezing and asthma exacerbation in infants and young children in Thailand.

Hepatitis B seroprevalence in Thailand: 12 years after hepatitis B vaccine integration into the national expanded programme on immunization

Objectives  To evaluate the impact of the universal hepatitis B (HB) vaccination programme on the prevalence of hepatitis B surface antigen (HBsAg) carriers and immunity to HB virus infection among children <18 years and to determine the HB seroprevalence in the Thai population.

Typing (A/B) and subtyping (H1/H3/H5) of influenza A viruses by multiplex real-time RT-PCR assays.

In this study, a specific and sensitive one-step multiplex real-time RT-PCR was developed in two assays by using primers and a number of specific locked nucleic acid (LNA)-mediated TaqMan probes which increase the thermal stability of oligonucleotides. The first assay consisted of primers and probes specific to the matrix (M1) gene of influenza A virus, matrix (M1) gene of influenza B virus and GAPDH gene of host cells for typing of influenza virus and verification by an internal control, respectively. The other assay employed primers and probes specific to the hemagglutinin gene of H1, H3 and H5 subtypes in order to identify the three most prominent subtypes of influenza A capable of infecting humans. The specificity results did not produce any cross reactivity with other respiratory viruses or other subtypes of influenza A viruses (H2, H4 and H6-H15), indicating the high specificity of the primers and probes used. The sensitivity of the assays which depend on the type or subtype being detected was approximately 10 to 10(3)copies/microl that depended on the types or subtypes being detected. Furthermore, the assays demonstrated 100% concordance with 35 specimens infected with influenza A viruses and 34 specimens infected with other respiratory viruses, which were identified by direct nucleotide sequencing. In conclusion, the multiplex real-time RT-PCR assays have proven advantageous in terms of rapidity, specificity and sensitivity for human specimens and thus present a feasible and attractive method for large-scale detection aimed at controlling influenza outbreaks.

Persistence of antibodies and immune memory to hepatitis B vaccine 20 years after infant vaccination in Thailand

Booster vaccination against hepatitis B (HBV) is not currently recommended, although debate continues on the duration of protection after priming. We assessed antibody persistence and immune memory to hepatitis B 20 years after priming with a recombinant HBV-vaccine during infancy. Infants were vaccinated at birth, 1, 2 and 12 months of age. A subset received a booster dose at Year 5. Antibody persistence was measured approximately yearly until Year 20. Immune memory was assessed by administration of HBV booster dose. At Year 20, anti-HBs seroprotection rates and GMCs tended to be higher in Year 5 boosted than unboosted recipients (83.9% versus 60.5%). After the Year 20 booster dose, anti-HBs anamnestic responses were within the same range 95.8% of subjects in both groups. Primary and booster vaccination with HBV-vaccine in infants induces sustained seroprotection and immune memory against hepatitis B for up to 20 years. Higher persisting seroprotection rates in subjects boosted at Year 5 did not translate into apparent differences in immune memory in a high endemic country.