Prophylactic Efficacy of Equine Immunoglobulin F(ab')2 Fragments Against Feline Parvovirus.

Feline parvovirus (FPV), a type of parvovirus prevalent worldwide, can cause foetal death and acute enteritis in adult cats with severe leukopenia, and yet there are no effective drugs to prevent or treat FPV. Here, the immune effects of two FPV vaccines on horses were compared. IgG was extracted from FPV-immunized horse sera. Equine F(ab')2 fragments were obtained from pepsin-digested IgG and then purified by protein-G column chromatography. The results showed that the inactivated FPV oil vaccine was more effective than the inactivated FPV propolis vaccine in helping healthy horses to produce hyper-immune serum. Four methods were tested, among which the optimized octanoic acid-ammonium sulphate precipitation method was proved to be the best process for extracting IgG. The optimal condition for preparing F(ab')2 by pepsin digestion was 30 °C for 3.5 h, and the content, purity and recovery of F(ab')2 were 8.64 mg/mL, 90.36% and 93.24%, respectively. Our equine immunoglobulin F(ab')2 fragments effectively neutralized activity in vitro against FPV, alleviated the clinical symptoms of FPV-infected cats, reduced the viral loads in the intestine and had prophylactic effects in FPV-infected cats. These results indicate that the F(ab')2 fragment prepared from inactivated FPV-immunized horses may be used as a prophylactic agent for diseases caused by FPV.

Seroprevalence and Potential Risk Factors of Bluetongue Virus Infection in Domestic Cattle and Goats in Guangxi Province, Southern China.

Bluetongue is one of the most important vector-borne viral diseases that can lead to significant economic losses as a result of reduction of productivity and even death in some susceptible ruminants. However, epidemiological information on bluetongue virus (BTV) infection in cattle and goats is scarce in China. To determine the seropositive rate and risk factors of BTV infection in cattle and goats in Guangxi province, a subtropical region in Southern China, a total of 548 cattle serum samples and 6567 goat serum samples collected from 13 cities across Guangxi province during 2003-2015 were analyzed and found that the seroprevalence is 44.5% (244/548) in cattle and 28.0% (1837/6567) in goats and the main BTV serotypes are BTV-1, -2, -4, and -8. Climatic zone, age, and species are found to be the likely risk factors for BTV infection. To our knowledge, this is the first large-scale serological survey for BTV infection in domestic cattle and goats in Guangxi province, Southern China.

Isolation, genetic analysis of the first Akabane virus from goat in China.

Akabane virus (AKAV) is an important insect-borne virus belonging to the genus Orthobunyavirus, the Peribunyaviridae family. An AKAV defined as GXDH 01 here, was isolated for the first time from blood from a sentinel goat in China in 2016, and its full-length open reading frames (ORFs) were sequenced in this study. Sequence analysis suggested that the isolate GXDH 01 probably had undergone a reassortment incident and acquired L segments from other strain originating from an attenuated vaccine, such as OBE-1. This study aims to provide more understanding as to the origin and epidemiology of AKAV in China.

Evaluation of a duplex reverse-transcription real-time PCR assay for the detection of encephalomyocarditis virus.

We evaluated a fluorogenic probe-based assay for the detection of encephalomyocarditis virus (EMCV) by comparing a set of published primers and probe to a new set of primers and probe. The published reagents failed to amplify a range of Australian isolates and an Italian reference strain of EMCV. In contrast, an assay based on 2 new sets of primers and probes that were run in a duplex reverse-transcription real-time PCR (RT-rtPCR) worked well, with high amplification efficiency. The analytical sensitivity was ~100-fold higher than virus isolation in cell culture. The intra-assay variation was 0.21-4.90%. No cross-reactivity was observed with a range of other porcine viruses. One hundred and twenty-two clinical specimens were tested simultaneously by RT-rtPCR and virus isolation in cell culture; 72 specimens gave positive results by RT-rtPCR, and 63 of these were also positive by virus isolation. Of 245 archived cell culture isolates of EMCV that were tested in the RT-rtPCR, 242 samples were positive. The new duplex RT-rtPCR assay is a reliable tool for the detection of EMCV in clinical specimens and for use in epidemiologic investigations.

Genetic diversity of bat orthohepadnaviruses in China and a proposed new nomenclature.

The orthohepadnaviruses, which include the major human pathogen hepatitis B virus, exist in a wide range of hosts. Since 2013, a large group of orthohepadnaviruses has been identified in bats worldwide and classified as 4 species within the genus Orthohepadnavirus. To further investigate orthohepadnaviruses in the Chinese bat population, 554 archived bat samples from 20 colonies covering 3 southern provinces were screened with results showing that 9 (1.6%) were positive. A systematic phylogenetic analysis has indicated the need for a new nomenclature for bat hepatitis B virus-like viruses: BtHBV, with the addition of 3 new species, one being divided into 6 genotypes. Viruses identified here shared 9.0-19.2% full genome divergence and classified into 3 different genotypes. This study illustrates the genetic diversity of orthohepadnaviruses in the Chinese bat population, and emphasizes need for further investigation of their public health significance.

Full genome sequence of the first bluetongue virus serotype 21 (BTV-21) isolated from China: evidence for genetic reassortment between BTV-21 and bluetongue virus serotype 16 (BTV-16).

Bluetongue (BT) is one of the most important insect-borne, non-contagious viral diseases of ruminants and can cause severe disease and death in sheep. Its pathogen, bluetongue virus (BTV) has a double-stranded RNA genome consisting of 10 segments that provides an opportunity for field and vaccine strains of different serotypes to reassort whilst simultaneously infecting the same animal. For the first time, we report the full-length genome sequence of a BTV strain of serotype 21 (5149E) isolated from sentinel cattle in Guangxi Province in China in 2015. Sequence analysis suggested that the isolate 5149E had undergone a reassortment incident and acquired seg-6 from an isolate of BTV-16 which originated from Japan. This study aims to provide more understanding as to the origin and epidemiology of BTV.

Molecular detection and sequence characterization of diverse rhabdoviruses in bats, China.

The Rhabdoviridae is among the most diverse families of RNA viruses and currently classified into 18 genera with some rhabdoviruses lethal to humans and other animals. Herein, we describe genetic characterization of three novel rhabdoviruses from bats in China. Of these, two viruses (Jinghong bat virus and Benxi bat virus) found in Rhinolophus bats showed a phylogenetic relationship with vesiculoviruses, and sequence analyses indicate that they represent two new species within the genus Vesiculovirus. The remaining Yangjiang bat virus found in Hipposideros larvatus bats were only distantly related to currently known rhabdoviruses.

Characterization of Akabane virus from domestic bamboo rat, Southern China.

To identify the causative agents in 3 large-scale outbreaks of encephalitis and death among farmed bamboo rats (Rhizomys pruinosus). The routine bacterial culture and identification were performed. There were no significant pathogenic bacteria isolated from the brain, heart, liver, spleen, lung, or kidney of diseased bamboo rats. Using PCR-based methods, we excluded the following as causative agent: pox virus, herpesvirus, adenovirus, lymphocytic choriomeningitis virus, rabies virus, and sendai virus. Furthermore, the homogenate from the diseased bamboo rats was subjected to viral metagenomic analysis which revealed 48506 filtered viral reads annotated to Akabane virus (AKAV) with >75% nucleotide identity, suggesting the presence of AKAVs in bamboo rats. Five novel AKAV isolates were successfully isolated and characterized. Furthermore the newly isolated AKAV isolate was used to demonstrate that it can reproduce the severe encephalitic and pneumonic disease in bamboo rats and mice. The findings add to the better understanding of AKAV epidemiology and to the prevention and control of Akabane diseases in China.

Group A Rotaviruses in Chinese Bats: Genetic Composition, Serology, and Evidence for Bat-to-Human Transmission and Reassortment.

Bats are natural reservoirs for many pathogenic viruses, and increasing evidence supports the notion that bats can also harbor group A rotaviruses (RVAs), important causative agents of diarrhea in children and young animals. Currently, 8 RVA strains possessing completely novel genotype constellations or genotypes possibly originating from other mammals have been identified from African and Chinese bats. However, all the data were mainly based on detection of RVA RNA, present only during acute infections, which does not permit assessment of the true exposure of a bat population to RVA. To systematically investigate the genetic diversity of RVAs, 547 bat anal swabs or gut samples along with 448 bat sera were collected from five South Chinese provinces. Specific reverse transcription-PCR (RT-PCR) screening found four RVA strains. Strain GLRL1 possessed a completely novel genotype constellation, whereas the other three possessed a constellation consistent with the MSLH14-like genotype, a newly characterized group of viruses widely prevalent in Chinese insectivorous bats. Among the latter, strain LZHP2 provided strong evidence of cross-species transmission of RVAs from bats to humans, whereas strains YSSK5 and BSTM70 were likely reassortants between typical MSLH14-like RVAs and human RVAs. RVA-specific antibodies were detected in 10.7% (48/448) of bat sera by an indirect immunofluorescence assay (IIFA). Bats in Guangxi and Yunnan had a higher RVA-specific antibody prevalence than those from Fujian and Zhejiang provinces. These observations provide evidence for cross-species transmission of MSLH14-like bat RVAs to humans, highlighting the impact of bats as reservoirs of RVAs on public health.IMPORTANCE Bat viruses, such as severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), Ebola, Hendra, and Nipah viruses, are important pathogens causing outbreaks of severe emerging infectious diseases. However, little is known about bat viruses capable of causing gastroenteritis in humans, even though 8 group A viruses (RVAs) have been identified from bats so far. In this study, another 4 RVA strains were identified, with one providing strong evidence for zoonotic transmission from bats to humans. Serological investigation has also indicated that RVA infection in bats is far more prevalent than expected based on the detection of viral RNA.

Genetic diversity of subgenotype 2.1 isolates of classical swine fever virus.

As the causative agent of classical swine fever, the economically devastating swine disease worldwide, classical swine fever virus (CSFV) is currently classified into the 11 subgenotypes, of which subgenotype 2.1 is distributed worldwide and showing more genetic diversity than other subgenotypes. Prior to this report, subgenotype 2.1 was divided into three sub-subgenotypes (2.1a-2.1c). To further analyze the genetic diversity of CSFV isolates in China, 39 CSFV isolates collected between 2004 and 2012 in two Chinese provinces Guangxi and Guangdong were sequenced and subjected to phylogenetic analysis together with reference sequences retrieved from GenBank. Phylogenetic analyses based on the 190-nt and/or 1119-nt full length E2 gene fragments showed that current CSFV subgenotype 2.1 virus isolates in the world could be divided into 10 sub-subgenotypes (2.1a-2.1j) and the 39 isolates collected in this study were grouped into 7 of them (2.1a-2.1c and 2.1g-2.1j). Among the 10 sub-subgenotypes, 2.1d-2.1j were newly identified. Sub-subgenotype 2.1d isolates were circulated only in India, however the rest 9 sub-subgenotypes were from China with some of them closely related to isolates from European and neighboring Asian countries. According to the temporal and spatial distribution of CSFV subgenotype 2.1 isolates, the newly classified 10 sub-subgenotypes were further categorized into three groups: dominant sub-subgenotype, minor sub-subgenotype and silent sub-subgenotype, and each sub-subgenotype can be found only in certain geographical areas. Taken together, this study reveals the complex genetic diversity of CSFV subgenotype 2.1 and improves our understanding about the epidemiological trends of CSFV subgenotype 2.1 in the world, particularly in China.

Isolation, complete genome sequencing, and phylogenetic analysis of the first Chuzan virus in China.

A Chuzan virus (CHUV), defined as GX871 here, was isolated from blood from a sentinel cattle firstly in China, and its full-length genome was sequenced in this study. The GX871 genome included 10 segments and 18914 bp, one base fewer than the CHUV prototype strain K-47 due to a one-base deletion in the 5' non-coding region of segment 8. A frameshift mutation was detected in a short coding region (1010-1026 nt) corresponding to the VP1 protein; this frameshift resulted in a five-amino acid mutation from 336CVLSY340 to 336YGAKL340. In addition, there were a one-base deletion at 1713 nt and a one-base insertion at 1682 nt in the 3' non-coding region of segment 5. Based on phylogenetic analysis of the deduced VP2 amino acid sequences, Palyam serogroup viruses were classified into three groups. The Chinese CHUV isolate GX871 was categorized into the same group as CHUV prototype strain K-47. The phylogenetic tree was divided into three clusters according to the geographical distribution of the partial nucleotide sequences of VP7, and this arrangement might define the geographical gene pool of CHUV.

Complete Genome Sequence of a Porcine Endogenous Retrovirus Isolated from a Bama Minipig in Guangxi, Southern China.

A porcine endogenous retrovirus (PERV) strain, PERV-A-BM, was isolated from a Bama minipig in Guangxi, China. This is the first entire genome sequence of PERV isolated from Guangxi Bama minipigs. The isolate is closely related to isolates from Wuzhishan miniature pigs and distantly related to isolates from large white pigs.

Novel hantavirus identified in black-bearded tomb bats, China.

Hantaviruses cause life-threatening diseases in human worldwide. Rodents, insectivores and bats are known hantaviral reservoirs, but lack of complete genomic sequences of bat-borne hantaviruses impedes phylogenetic and evolutionary comparison with those of rodents and insectivores. Here, a novel bat-borne hantavirus, Laibin virus (LBV), has been identified in a black-bearded tomb bat in China. The complete genomic sequence shows that LBV is only distantly related to all previously known bat-borne hantaviruses.

[Preparation and bioactivity of anti-human red blood cell ScFv and CSFV E2 bifunctional fusion protein].

The aim of this study is to construct a bifunctional fusion protein, which can conjugate both human red blood cells and antibodies against classical swine fever virus (CSFV). We respectively amplified 2E8ScFv and mE2 genes from different recombinant vectors, in which 2E8ScFv gene is the single chain Fv gene against H antigen of human red blood cells, whereas mE2 gene is the main antigen coding region gene of CSFV E2 protein. We used overlap extension PCR to obtain an artificial fusion gene segment 2E8mE2 containing genes of Both 2E8ScFv and mE2, then ligated into the expression vector pET-DsbA and expressed in Escherichia coli BL21(DE3) PlysS host cells, after induced with IPTG the target fusion protein was successfully expressed and identified in inclusion bodies by SDS-PAGE and Western blotting. We purified the fusion protein and renatured it from inclusion bodies to obtain a native state of well biological activity. The Erythrocyte agglutination test results indicated that the fusion protein can conjugate both human red blood cells and antibodies of CSFV.