Aunyaratana Thontiravong

Pandemic (H1N1) 2009 virus on commercial swine farm, Thailand.

A swine influenza outbreak occurred on a commercial pig farm in Thailand. Outbreak investigation indicated that pigs were co-infected with pandemic (H1N1) 2009 virus and seasonal influenza (H1N1) viruses. No evidence of gene reassortment or pig-to-human transmission of pandemic (H1N1) 2009 virus was found during the outbreak.

Quail as a potential mixing vessel for the generation of new reassortant influenza A viruses.

Quail has been proposed as one of the intermediate hosts supporting the generation of newly reassortant influenza A viruses (IAVs) with the potential to infect humans. To evaluate the role of quail as an intermediate host of IAVs, co-infections of quail with swine-origin pandemic H1N1 2009 (pH1N1) and low pathogenic avian influenza (LPAI) duck H3N2 (dkH3N2) viruses (n=10) or endemic Thai swine H1N1 (swH1N1) and dkH3N2 viruses (n=10) were conducted. Three additional groups of five quail were each inoculated with pH1N1, swH1N1 and dkH3N2 as control groups to verify that each virus can infect quail. Our result showed that co-infected quail shed higher viral titers from the respiratory tract than single virus infected quail. This study confirmed that reassortant viruses could be readily generated in the respiratory tract of quail from both the pH1N1/dkH3N2 co-infected group (100% of quail generating reassortant viruses) and the swH1N1/dkH3N2 (33% of quail generating reassortant viruses) co-infected group without discernible clinical signs. The reassortment efficacy between the two combination of viruses was different in that the frequency of reassortant viruses was significantly higher in pH1N1/dkH3N2 co-infected quail (21.4%) compared to swH1N1/dkH3N2 co-infected quail (0.8%), indicating that gene combinations in pH1N1 have a higher potential to reassort with dkH3N2 compared to swH1N1. In summary, our result confirmed that quail could be an intermediate host of IAVs for generating new reassortant viruses. Our finding highlights the importance of monitoring IAVs especially pH1N1 in quail.

Tembusu-Related Flavivirus in Ducks, Thailand.

Since 2013, outbreaks of disease caused by duck Tembusu virus (DTMUV) have been observed in layer and broiler duck farms in Thailand. The virus is closely related to Chinese DTMUVs and belongs to the Ntaya group of mosquitoborne flaviviruses. These findings represent the emergence of DTMUV in ducks in Thailand.

Comparative study of pandemic (H1N1) 2009, swine H1N1, and avian H3N2 influenza viral infections in quails

Quail has been proposed to be an intermediate host of influenza A viruses. However, information on the susceptibility and pathogenicity of pandemic H1N1 2009 (pH1N1) and swine influenza viruses in quails is limited. In this study, the pathogenicity, virus shedding, and transmission characteristics of pH1N1, swine H1N1 (swH1N1), and avian H3N2 (dkH3N2) influenza viruses in quails was examined. Three groups of 15 quails were inoculated with each virus and evaluated for clinical signs, virus shedding and transmission, pathological changes, and serological responses. None of the 75 inoculated (n = 45), contact exposed (n = 15), or negative control (n = 15) quails developed any clinical signs. In contrast to the low virus shedding titers observed from the swH1N1-inoculated quails, birds inoculated with dkH3N2 and pH1N1 shed relatively high titers of virus predominantly from the respiratory tract until 5 and 7 DPI, respectively, that were rarely transmitted to the contact quails. Gross and histopathological lesions were observed in the respiratory and intestinal tracts of quail inoculated with either pH1N1 or dkH3N2, indicating that these viruses were more pathogenic than swH1N1. Sero-conversions were detected 7 DPI in two out of five pH1N1-inoculated quails, three out of five quails inoculated with swH1N1, and four out of five swH1N1-infected contact birds. Taken together, this study demonstrated that quails were more susceptible to infection with pH1N1 and dkH3N2 than swH1N1.

Prevalence of respiratory viruses isolated from dogs in Thailand during 2008-2009

Abstract Background: A highly contagious respiratory disease in canines is infectious tracheobronchitis or kennel cough characterized by inflammation of the upper respiratory tract. The cause of kennel cough has been associated with multiple or complex agents such as canine adeno virus (CAV), canine influenza virus (CIV), canine distemper virus (CDV), and canine para influenzavirus (CPIV). Objective: Study the prevalence of canine respiratory viruses detected from in Thailand during 2008-2009. Methods: Nasal swab samples collected from 102 healthy dogs and 109 dogs with respiratory diseases. Then CAV, CIV, CDV, and CPIV were detected by in-house nested PCR and further confirmed by nucleotide sequencing. Results: Nested PCR showed that primers designed and used in this study yielded high specificity without any non-specific amplification. The prevalence of CAV, CIV, CDV and CPIV in healthy dogs was 0%, 2.94%, 2.94%, and 0.98%, whereas that found in dogs with respiratory diseases was 9.17%, 1.83%, 2.75%, and 11.93%, respectively. In healthy dogs, co-infection with CPIV + CDV was detected in only 0.98%. On the other hand, dogs with respiratory symptoms showed multiple infections with CAV + CIV in 1.83%, CIV + CPIV in 0.92%, CAV + CPIV in 1.83%, and CAV + CDV + CPIV in 0.92%. Conclusion: The prevalence data obtained from this study may be useful for outbreak preventions and to raise awareness of potential transmission of the newly emerged canine influenza virus to humans.

The presence of duck Tembusu virus in Thailand since 2007: A retrospective study

Duck Tembusu virus (DTMUV), a newly emerging virus in ducks, was first reported in China in 2010. However, an unknown severe contagious disease associated with severe neurological signs and egg production losses in ducks, resembling to DTMUV infection, was observed in Thailand since 2007. To determine the presence of DTMUV in 2007, the clinical samples from affected ducks collected in 2007 were tested for DTMUV using pathological and virological analyses. Gross and histopathological lesions of affected ducks were mostly restricted to the ovary, brain and spinal cord, and correlated with the presence of flavivirus antigen in the brain and spinal cord samples. Subsequently, DTMUV was identified by RT-PCR and nucleotide sequencing of the polyprotein gene. Phylogenetic analysis of the polyprotein gene sequence revealed that the 2007 Thai DTMUV was a unique virus, belonged within DTMUV cluster 1, but distinctively separated from the Malaysian DTMUV, which was the most closely related DTMUV. It is interesting to note that the 2007 Thai DTMUV was genetically different from the currently circulating Thai and Chinese DTMUVs, which belonged to cluster 2. Our findings indicated that the 2007 Thai DTMUV emerged earlier from a common ancestor with the recently reported DTMUVs; however, it was genetically distinctive to any of the currently circulating DTMUVs. In conclusion, our data demonstrated the presence of DTMUV in the Thai ducks since 2007, prior to the first report of DTMUV in China in 2010. This study indicates that DTMUV may have circulated in the region long before 2010 and highlights high genetic diversity of DTMUVs in Asia.

In vitro characterization of the novel H3N1 reassortant influenza viruses from quail

Quail is considered as an intermediate host for generation of the novel reassortant influenza A viruses (IAVs). In this study, we evaluated the replication ability of the three novel H3N1 reassortant viruses recovered from pandemic H1N1 2009 (pH1N1) and duck H3N2 (dkH3N2) co-infected quail generated from our previous study in embryonated chicken eggs, mammalian (MDCK) and human lung derived (A549) cells. Our study demonstrated that all of the reassortant viruses replicated efficiently in avian and mammalian cells, albeit with slightly lower titers than the parental viruses. Of note, all of the reassortant viruses showed enhanced replication in human lung derived A549 cells compared to their parental viruses. Interestingly, among the reassortant viruses tested, a reassortant virus (P(NA,NS)-DK) containing NA and NS genes derived from pH1N1 and the other genes from dkH3N2 exhibited the highest replication ability in all in vitro models, indicating a high level of gene compatibility of this reassortant virus. Our results highlight the potential role of quail as intermediate hosts for the generation of the viable reassortant viruses with ability to replicate efficiently in avian, mammalian, and particularly human lung derived cells. These findings emphasize the need for the continuous IAV surveillance in quail to prevent the risk of the emergence of the novel viable reassortant viruses.

Serological evidence of duck Tembusu virus infection in free-grazing ducks, Thailand

Duck Tembusu virus (DTMUV) has been reported in ducks raised in farming system since its emergence in 2010. No information is available on DTMUV infection in free-grazing ducks, which are commonly raised and widespread in several Asian countries. To determine the presence of DTMUV infection in free-grazing ducks in Thailand, retrospective serum samples collected from 1,000 free-grazing ducks during 2008-2015 were tested for DTMUV infection. Our result showed that 91 (9.10%) were positive for DTMUV neutralizing antibodies and DTMUV seropositive ducks have been detected in Thailand since 2008. To further investigate the seroprevalence and geographic distribution of DTMUV infection in free-grazing ducks in Thailand, a cross-sectional serological survey of DTMUV was conducted in 2016. Of 1,200 free-grazing ducks in the 60 flocks from 20 provinces located in the major free-grazing duck raising areas of Thailand, 365 (30.42%) were positive for DTMUV neutralizing antibodies and 56 flocks (93.33%) had at least one DTMUV seropositive duck. Additionally, DTMUV seropositive ducks were observed in all provinces tested. In conclusion, our data demonstrated the presence of DTMUV infection in free-grazing ducks since 2008 and widespread DTMUV infection in free-grazing ducks in Thailand with a relatively high seroprevalence. These findings suggest the potential role of free-grazing ducks in the dissemination of DTMUV and highlight the necessity of systemic DTMUV surveillance in free-grazing ducks in addition to farm ducks for early detection, prevention, and control of this emerging disease.

Persistence of Chlamydia psittaci in Various Temperatures and Times

SUMMARY Chlamydia psittaci, an obligate intracellular gram-negative bacteria, causes an important zoonotic disease in humans, namely, psittacosis. The objective of this study was to determine the persistent viability of C. psittaci at various temperature conditions. The cloacal swab samples were collected from feral and racing pigeons to find a C. psittaci field strain. The bacterial isolation showed that 1.3% of feral pigeons were PCR positive, while all samples of racing pigeons were PCR negative. Also, bacterial characterization suggested that it belonged to genotype B, which had bacterial titers 3.2 and 3.89 log 50% lethal dose/ml, respectively. A bacterial persistence test was performed, and the results showed that C. psittaci could survive at 56 C for up to 72 hr. In conclusion, C. psittaci could be found in feral pigeons in central Thailand. The bacteria can survive in equatorial temperature areas. This study was the first to report that C. psittaci could survive and has infectivity at 56 C for 72 hr. Therefore, awareness of C. psittaci infection in humans is necessary and should be a public health concern.