Localization of goose haemorrhagic polyomavirus in naturally infected geese using in situ hybridization.

Goose haemorrhagic polyomavirus (GHPV) is the aetiological agent of haemorrhagic nephritis enteritis of geese (HNEG), a fatal disease that impacts geese and has been recorded only in Europe. The present study describes the first clinical cases of HNEG in Taiwan and the phylogenesis of Taiwanese GHPV, and it elucidates the pathogenesis of GHPV infection using in situ hybridization (ISH). The genomes of Taiwanese GHPV were highly similar to the previously reported strains. The diseased geese showed various degrees of vascular damage, especially in the digestive tract. The affected geese in the early stage showed transmural haemorrhagic enteritis in the intestine. In the middle to late stages, the most obvious lesion was hypoxic necrosis of renal tubules around intralobular central veins. Mineralization deposited in the kidney and systemic gout were also found. ISH revealed GHPV DNA in the vascular endothelial cells throughout the body, but not in the parenchymal cells of organs. Accordingly, the pathogenesis of GHPV infection was consistent with viral tropism in the endothelial cells. Specific attack of vascular endothelium by GHPV resulted in endothelial cell necrosis and subsequent increases of blood vessel permeability, as well as secondary circulation disorders, such as oedema, haemorrhage, and ischaemic necrosis in the adjacent parenchyma. RESEARCH HIGHLIGHTS Cell tropism of GHPV is determined by in situ hybridization. The tropism results in vascular dysfunction and subsequent pathobiology. Haemorrhagic nephritis and enteritis of geese described outside Europe for the first time.

Lyssavirus in Japanese Pipistrelle, Taiwan.

A putative new lyssavirus was found in 2 Japanese pipistrelles (Pipistrellus abramus) in Taiwan in 2016 and 2017. The concatenated coding regions of the virus showed 62.9%-75.1% nucleotide identities to the other 16 species of lyssavirus, suggesting that it may be representative of a new species of this virus.

Detection of Rabies Virus in a Yellow-throated Marten (Martes flavigula chrysospila) in Taiwan.

In June 2021, a yellow-throated marten (Martes flavigula chrysospila) submitted for postmortem examination was diagnosed as rabid through laboratory testing. The rabies virus detected was closest phylogenetically to viruses of ferret badgers (Melogale moschata subaurantiaca) in Taiwan, indicating spillover infection from the primary reservoir in this area, the ferret badger.

Novel Bat Lyssaviruses Identified by Nationwide Passive Surveillance in Taiwan, 2018-2021.

Bat lyssaviruses were identified in Taiwan's bat population during 2016-2017. The lyssavirus surveillance system was continuously conducted to understand the epidemiology. Through this system, the found dead bats were collected for lyssavirus detection by direct fluorescent antibody test and reverse transcription polymerase chain reaction. Three bats were identified as positive during 2018-2021. A novel lyssavirus, designated as Taiwan bat lyssavirus 2, was detected in a Nyctalus plancyi velutinus. This lyssavirus had less than 80% nucleotide identity in the nucleoprotein (N) gene with other lyssavirus species, forming a separate branch in the phylogenetic analysis. The other two cases were identified in Pipistrellus abramus (Japanese pipistrelles); they were identified to be similar to the former lyssavirus identified in 2016-2017, which was renominated as Taiwan bat lyssavirus 1 (TWBLV-1) in this study. Even though one of the TWBLV-1 isolates showed high genetic diversity in the N gene compared with other TWBLV-1 isolates, it may be a TWBLV-1 variant but not a new species based on its high amino acid identities in the nucleoprotein, same host species, and same geographic location as the other TWBLV-1.

Standard Operating Procedure for Lyssavirus Surveillance of the Bat Population in Taiwan.

Viruses within the genus Lyssavirus are zoonotic pathogens, and at least seven lyssavirus species are associated with human cases. Because bats are natural reservoirs of most lyssaviruses, a lyssavirus surveillance program of bats has been conducted in Taiwan since 2008 to understand the ecology of these viruses in bats. In this program, non-governmental bat conservation organizations and local animal disease control centers cooperated to collect dead bats or bats dying of weakness or illness. Brain tissues of bats were obtained through necropsy and subjected to direct fluorescent antibody test (FAT) and reverse transcription polymerase chain reaction (RT-PCR) for detection of lyssavirus antigens and nucleic acids. For the FAT, at least two different rabies diagnosis conjugates are recommended. For the RT-PCR, two sets of primers (JW12/N165-146, N113F/N304R) are used to amplify a partial sequence of the lyssavirus nucleoprotein gene. This surveillance program monitors lyssaviruses and other zoonotic agents in bats. Taiwan bat lyssavirus is found in two cases of the Japanese pipistrelle (Pipistrellus abramus) in 2016-2017. These findings should inform the public, health professionals, and scientists of the potential risks of contacting bats and other wildlife.

Detection of reassortant H5N6 clade 2.3.4.4 highly pathogenic avian influenza virus in a black-faced spoonbill (Platalea minor) found dead, Taiwan, 2017.

A H5N6 highly pathogenic avian influenza virus (HPAIV) was detected in a black-faced spoonbill (Platalea minor) found dead in Taiwan during December 2017. Genome sequencing and phylogenetic analyses suggest the hemagglutinin gene belongs to H5 clade 2.3.4.4 Group B. All genes except neuraminidase gene shared high levels of nucleotide identity with H5N8 HPAIV identified from Europe during 2016-2017. Genetically similar H5N6 HPAIV was also identified from Japan during November 2017. Enhanced surveillance is required in this region.

Multiple models of porcine teschovirus pathogenesis in endemically infected pigs.

Porcine teschoviruses (PTVs) belong to the genus Teschovirus within the family Picornaviridae. PTVs are universal contaminants in pig herds in endemic and multi-infection status. To further the understanding of PTV pathogenesis in endemically infected pigs, a set of samples was studied by real time reverse transcription PCR (qRT-PCR) to quantitate viral loads in tissues and by in situ hybridization (ISH) to locate PTV signals in target cells, both targeting the 5'-NTR. cRNA of PTV-1 and PTV-7, in vitro transcribed from cloned fragments of 5'-NTR of 2 viruses, was used to construct standard curves and to run parallel in qRT-PCR, which had detection limits of 10(1) copies/per reaction, with a linearity in between 10(1) and 10(7) copies/per reaction and correlation coefficients of 0.997-0.9988. The qRT-PCR specifically amplified RNA from PTV-1 to -11, while excluding those of Sapelovirus, PEV-9 and PEV-10. Inguinal lymph node (LN) had the highest viral load of all (assuming 100%), followed by ileac LN (89-91%), tonsil (66-68%), ileum (59-60%), spleen (38-40%), and kidney (30-31%), with the least in brain (22.9%) of the inguinal LN. The 22.9% load in brain was higher than that anticipated from a simple fecal-oral-viremia operative model. The results suggested in addition that intranasal infection and retrograding axonal infection from the tonsils were equally operative and significant. ISH revealed PTV signals in a wider variety of tissue cell types than before. PTV signals were noted most impressively in neurons of the cerebral cortex and hippocampus and in the dark zone of the germinal center and adjacent paracortex of regional LN. Multiple operative models indicated that PTVs seemed to have no difficulty invading the brain. The key to whether encephalitis would ensue resided in the animal's immune status and topographic differences of neurons' susceptibilities to PTVs. When common co-infected agents are present, as is typical in the field, PTVs may synergize in causing diseases.

The role of porcine teschovirus in causing diseases in endemically infected pigs.

Porcine teschoviruses (PTVs) belong to the genus Teschovirus within the family Picornaviridae. Hitherto, PTVs have had 13 serotypes associated with a variety of clinical diseases. The virulent PTV-1 strains were associated with highly fatal, nonsuppurative encephalomyelitis of pigs (Teschen disease) in the 1930-1950s. Today, less virulent Talfan strains of PTV-1 are more widespread, and PTVs have contaminated swine herds worldwide (endemic or enzootic) together with a variety of common swine pathogens (multi-infection status). The aim of this study was to investigate the extent to which PTVs play a role in causing diseases in the field, under the endemic and multi-infection situation, when most pigs in the herds are infected and immune. Based on the fecal-oral model of pathogenesis, a set of 15 organs were collected from 30 culled post-weanling piglets of 4-8 weeks old. For nested RT-PCR targeted on the 5'-NTR, the PTV detection rate was 96.7% (by heads), confirming the endemic status, and infection was most commonly detected in the intestines (averaged 61%) and lymphoid organs (averaged 59%), followed by visceral organs (averaged 37%) and the CNS (different parts varied from 17 to 47%). The correlation of PTVs detected by nested RT-PCR and a histological lesion were analyzed by Chi-square test showing that in the field situation only non-suppurative encephalitis in the caudal part of the brain (P=0.054) may be marginal significantly attributed to infection by PTVs. By genotyping based on partial VP1 sequences, 5 serotypes, namely PTV-1, -4, -6, -7, and -11, were identified, with some animals having two serotypes co-existed in different organs.