Severe fever with thrombocytopenia syndrome (SFTS), an emerging tick-borne zoonosis, has been rapidly spread in many Asian counties since 2010, which raises the great concern in East Asia. Nevertheless, the infection status of SFTS in Taiwan remains unclear. To investigate the existence of SFTSV in Taiwan, a total of 151 serum samples collected from 31 sheep, 63 bovine and 57 dogs were enrolled this study. Furthermore, 360 adult female Rhipicephalus microplus were also included. One-step RT-nested PCR and IgG ELISA were conducted to test SFTSV specific RNA and antibodies, respectively. The result provided the first evidence of the existence of SFTSV RNA and antibodies in ruminants and ticks in Taiwan.

Infectious bursal disease virus (IBDV) causes a highly contagious disease in young chicks and leads to significant economic losses in the poultry industry. The capsid protein VP2 of IBDV plays an important role in virus binding and cell recognition. VP2 forms a subviral particle (SVP) with immunogenicity similar to that of the IBDV capsid. In the present study, we first showed that SVP could inhibit IBDV infection to an IBDV-susceptible cell line, DF-1 cells, in a dose-dependent manner. Second, the localizations of the SVP on the surface of DF-1 cells were confirmed by fluorescence microscopy, and the specific binding of the SVP to DF-1 cells occurred in a dose-dependent manner. Furthermore, the attachment of SVP to DF-1 cells was inhibited by an SVP-induced neutralizing monoclonal antibody against IBDV but not by denatured-VP2-induced polyclonal antibodies. Third, the cellular factors in DF-1 cells involved in the attachment of SVP were purified by affinity chromatography using SVP bound on the immobilized Ni 2؉ ions. A dominant factor was identified as being chicken heat shock protein 90 (Hsp90) (cHsp90) by mass spectrometry. Results of biotinylation experiments and indirect fluorescence assays indicated that cHsp90 is located on the surface of DF-1 cells. Virus overlay protein binding assays and far-Western assays also concluded that cHsp90 interacts with IBDV and SVP, respectively. Finally, both Hsp90 and anti-Hsp90 can inhibit the infection of DF-1 cells by IBDV. Taken together, for the first time, our results suggest that cHsp90 is part of the putative cellular receptor complex essential for IBDV entry into DF-1 cells. Infectious bursal disease virus (IBDV), a member of genusAvibirnavirus of the family Birnaviridae, causes a highly contagious disease in young chicks (27). Two serotypes (serotypes 1 and 2) of IBDV have been documented. Serotype 1 showed different degrees of pathogenicity and mortality in chicks, and serotype 2 was avirulent. As with all viruses, IBDV needs to penetrate target cells to cause infection. Chicken B lymphocytes are the primary target for virulent serotype 1 strains of IBDV, and the infection causes a functional loss of the bursa of Fabricius and severe immunodepression. However, other susceptible cells have also been reported (17). Viral attachment is the first step in virus infection (41). The distribution of a virus receptor mainly determines the cell and tissue tropism of the virus (1, 11) and the site of pathology associated with infection (9, 26). Thus, study of virus infection at the levels of virus binding, receptor identification, and even uncoating is critical for an understanding of the virus-host cell interactions and pathogenesis of viral disease (24, 32). Additionally, viral entry and uncoating can serve as targets for the development of antiviral drugs (39,42). Recent advances in the understanding of the viral infection process have made it possible to develop new approaches to block the entry of viruses (31) and to prevent diseases (41). However, the identificatio...

Potential synergism between florfenicol (FF) and thiamphenicol (TAP) was investigated for in vitro efficacy against Actinobacillus pleuropneumoniae and/or Pasteurella multocida as well as in vivo efficacy in swine. Among isolates of A. pleuropneumoniae (n = 58) and P. multocida (n = 79) from pigs in Taiwan that were tested, high percentages showed resistance to FF (52 and 53%, respectively) and TAP (57 and 53%, respectively). Checkerboard microdilution assay indicated that synergism [fractional inhibitory concentration index (FICI) ≤ 0.5] was detected in 17% of A. pleuropneumoniae (all serovar 1) and 24% of P. multocida isolates. After reconfirming the strains showing FICI ≤ 0.625 with time kill assay, the synergism increased to around 32% against both bacteria and the number could further increase to 40% against resistant A. pleuropneumoniae and 65% against susceptible P. multocida isolates. A challenge-treatment trial in pigs with P. multocida showed that the FF + TAP dosage at ratios correspondent to their MIC deduction was equally effective to the recommended dosages. Further on the combination, the resistant mutation frequency is very low when A. pleuropneumoniae is grown with FF + TAP and similar to the exposure to sub-inhibitory concentration of FF or TAP alone. The degree of minimum inhibitory concentration (MIC) reduction in FF could reach 75% (1/4 MIC) or more (up to 1/8 MIC for P. multocida, 1/16 for A. pleuropneumoniae) when combined with 1/4 MIC of TAP (or 1/8 for A. pleuropneumoniae). The synergism or FICI ≤ 0.625 of FF with oxytetracycline (47%), doxycycline (69%), and erythromycin (56%) was also evident, and worth further investigation for FF as a central modulator facilitating synergistic effects with these antimicrobials. Taken together, synergistic FF + TAP combination was effective against swine pulmonary isolates of A. pleuropneumoniae and P. multocida both in vitro and in vivo. Thus, this study may offer a potential alternative for the treatment of A. pleuropneumoniae and P. multocida infections and has the potential to greatly reduce drug residues and withdrawal time.

Since the first discovery of severe fever with thrombocytopenia syndrome virus (SFTSV) in China in 2009, SFTSV has rapidly spread through other Asian countries, including Japan, Korea, Vietnam and Pakistan, in chronological order. Taiwan reported its first discovery of SFTSV in sheep and humans in 2020. However, the prevalence of SFTSV in domestic and wildlife animals and the geographic distribution of the virus within the island remain unknown. A total of 1324 animal samples, including 803 domestic ruminants, 521 wildlife animals and 47 tick pools, were collected from March 2021 to December 2022 from 12 counties and one terrestrial island. The viral RNA was detected by a one-step real-time reverse transcription polymerase chain reaction (RT-PCR). Overall, 29.9% (240/803) of ruminants showed positive SFTSV RNA. Sheep had the highest viral RNA prevalence of 60% (30/50), followed by beef cattle at 28.4% (44/155), goats at 28.3% (47/166), and dairy cows at 27.5% (119/432). The bovine as a total of dairy cow and beef cattle was 27.8% (163/587). The viral RNA prevalence in ticks (predominantly Rhipicephalus microplus) was similar to those of ruminants at 27.7% (13/47), but wild animals exhibited a much lower prevalence at 1.3% (7/521). Geographically the distribution of positivity was quite even, being 33%, 29.1%, 27.5% and 37.5% for northern, central, southern and eastern Taiwan, respectively. Statistically, the positive rate of beef cattle in the central region (55.6%) and dairy cattle in the eastern region (40.6%) were significantly higher than the other regions; and the prevalence in Autumn (September–November) was significantly higher than in the other seasons (p < 0.001). The nationwide study herein revealed for the first time the wide distribution and high prevalence of SFTSV in both domestic animals and ticks in Taiwan. Considering the high mortality rate in humans, surveillance of other animal species, particularly those in close contact with humans, and instigation of protective measures for farmers, veterinarians, and especially older populations visiting or living near farms or rural areas should be prioritized.

A double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) for detection of the soft-shelled turtle iridovirus (STIV) was developed using a specific monoclonal antibody (mAb) against STIV and anti-STIV rabbit serum. Using DAS-ELISA, the detection limit of STIV was found to be 10(3)PFU/ml. The positive rate of 15 STIV samples was 100%, while the positive rate of 100 other aquatic virus samples was 0%. These data show that DAS-ELISA is highly specific and sensitive for the detection of STIV. In clinical tests, 128 samples isolated from pond-reared turtles were subjected to DAS-ELISA and PCR. The overall agreement between the results obtained by DAS-ELISA and PCR was 98.4%. The results indicate that the DAS-ELISA method could be used for diagnosing diseases caused by STIV.