Molecular evolution and characterization of novel Seneca Valley virus (SVV) strains in South China

Seneca Valley virus (SVV) is an emerging swine virus associated with porcine vesicular disease. From June to the end of 2017, five SVV strains were isolated from the swine herds in Guangdong, China. Complete genomic sequences of these newly discovered SVV strains were analyzed by genomic and phylogenetic analysis. The results revealed that these SVV strains could be grouped into five genetic branches together with most of other Chinese strains. Interestingly, it is for the first time that a stretch of 11-nucleotide insertion was found in the 5' UTR region of SVV GD04/2017 strain. Additionally, phylogenetic analysis based on the ORF and VP1 genes showed that the SVV GD06/2017 strain is significantly distinct from all previous Chinese SVV strains. Furthermore, the five SVV strains displayed similar growth kinetics in the ST-R cell line, while the SVV GD04/2017 and GD06/2017 strains presented relatively slower rates than the GD01/2017 and GD03/2017 strains. The findings of this study indicate the emergence of novel SVV strains in China, which would increase the knowledge about SVV genetic diversity and reinforce the importance of SVV surveillance.

Lethal Respiratory Disease Associated with Human Rhinovirus C in Wild Chimpanzees, Uganda, 2013

We describe a lethal respiratory outbreak among wild chimpanzees in Uganda in 2013 for which molecular and epidemiologic analyses implicate human rhinovirus C as the cause. Postmortem samples from an infant chimpanzee yielded near-complete genome sequences throughout the respiratory tract; other pathogens were absent. Epidemiologic modeling estimated the basic reproductive number (R₀) for the epidemic as 1.83, consistent with the common cold in humans. Genotyping of 41 chimpanzees and examination of 24 published chimpanzee genomes from subspecies across Africa showed universal homozygosity for the cadherin-related family member 3 CDHR3-Y₅₂₉ allele, which increases risk for rhinovirus C infection and asthma in human children. These results indicate that chimpanzees exhibit a species-wide genetic susceptibility to rhinovirus C and that this virus, heretofore considered a uniquely human pathogen, can cross primate species barriers and threatens wild apes. We advocate engineering interventions and prevention strategies for rhinovirus infections for both humans and wild apes.

The development of two field-ready reverse transcription loop-mediated isothermal amplification assays for the rapid detection of Seneca Valley virus 1

Seneca Valley virus 1 (SVV-1) has been associated with vesicular disease in swine, with clinical signs indistinguishable from those of other notifiable vesicular diseases such as foot-and-mouth disease. Rapid and accurate detection of SVV-1 is central to confirm the disease causing agent, and to initiate the implementation of control processes. The development of rapid, cost-effective diagnostic assays that can be used at the point of sample collection has been identified as a gap in preparedness for the control of SVV-1. This study describes the development and bench validation of two reverse transcription loop-mediated amplification (RT-LAMP) assays targeting the 5'-untranslated region (5'-UTR) and the VP3-1 region for the detection of SVV-1 that may be performed at the point of sample collection. Both assays were able to demonstrate amplification of all neat samples diluted 1/100 in negative pig epithelium tissue suspension within 8 min, when RNA was extracted prior to the RT-LAMP assay, and no amplification was observed for the other viruses tested. Simple sample preparation methods using lyophilized reagents were investigated, to negate the requirement for RNA extraction. Only a small delay in the time to amplification was observed for these lyophilized reagents, with a time from sample receipt to amplification achieved within 12 min. Although diagnostic validation is recommended, these RT-LAMP assays are highly sensitive and specific, with the potential to be a useful tool in the rapid diagnosis of SVV-1 in the field.

Asian black bear (Ursus thibetanus) picornavirus related to seal aquamavirus A

The complete genome of a bear picornavirus 1 (BePV-1) in the viscera of an Asian black bear (Ursus thibetanus) from China was characterized using viral metagenomics and RT-PCR/Sanger sequencing. The genome of BePV1 is 6703 nt long, contains a type-IV IRES 5'UTR with the '8-like' motif, encodes a 2053-aa-long polyprotein showing a 3-4-4 organization pattern and two 2A genes. BePV-1 showed the highest overall genome nucleotide sequence identity of 71.7% to a picornavirus genome from an Arctic ringed seal (Phoca hispida) from Canada, classified as a member of the species Aquamavirus A, currently the only one in the genus Aquamavirus. Phylogenetic and genetic distance analyses of P1 and 3D indicated that Asian bear picornavirus (aquamavirus B) represents the second sequenced member of the genus Aquamavirus.

Nanopore sequencing as a revolutionary diagnostic tool for porcine viral enteric disease complexes identifies porcine kobuvirus as an important enteric virus

Enteric diseases in swine are often caused by different pathogens and thus metagenomics are a useful tool for diagnostics. The capacities of nanopore sequencing for viral diagnostics were investigated here. First, cell culture-grown porcine epidemic diarrhea virus and rotavirus A were pooled and sequenced on a MinION. Reads were already detected at 7 seconds after start of sequencing, resulting in high sequencing depths (19.2 to 103.5X) after 3 h. Next, diarrheic feces of a one-week-old piglet was analyzed. Almost all reads (99%) belonged to bacteriophages, which may have reshaped the piglet's microbiome. Contigs matched Bacteroides, Escherichia and Enterococcus phages. Moreover, porcine kobuvirus was discovered in the feces for the first time in Belgium. Suckling piglets shed kobuvirus from one week of age, but an association between peak of viral shedding (106.42-107.01 copies/swab) and diarrheic signs was not observed during a follow-up study. Retrospective analysis showed the widespread (n = 25, 56.8% positive) of genetically moderately related kobuviruses among Belgian diarrheic piglets. MinION enables rapid detection of enteric viruses. Such new methodologies will change diagnostics, but more extensive validations should be conducted. The true enteric pathogenicity of porcine kobuvirus should be questioned, while its subclinical importance cannot be excluded.

Avian keratin disorder of Alaska black-capped chickadees is associated with Poecivirus infection

BACKGROUND

Avian keratin disorder (AKD) is an epizootic of debilitating beak deformities, first documented in black-capped chickadees (Poecile atricapillus) in Alaska during the late 1990s. Similar deformities have now been recorded in dozens of species of birds across multiple continents. Despite this, the etiology of AKD has remained elusive, making it difficult to assess the impacts of this disease on wild populations. We previously identified an association between infection with a novel picornavirus, Poecivirus, and AKD in a small cohort of black-capped chickadees.

METHODS

To test if the association between Poecivirus and AKD holds in a larger study population, we used targeted PCR followed by Sanger sequencing to screen 124 symptomatic and asymptomatic black-capped chickadees for Poecivirus infection. We further compared the efficacy of multiple non-terminal field sampling methods (buccal swabs, cloacal swabs, fecal samples, and blood samples) for Poecivirus screening. Finally, we used both in situ hybridization and a strand-specific expression assay to localize Poecivirus to beak tissue of AKD-positive individuals and to determine if virus is actively replicating in beak tissue.

RESULTS

Poecivirus was detected in 28/28 (100%) individuals with AKD, but only 9/96 (9.4%) asymptomatic individuals with apparently normal beaks (p < 0.0001). We found that cloacal swabs are the most sensitive of these sample types for detecting Poecivirus in birds with AKD, but that buccal swabs should be combined with cloacal swabs in evaluating the infection status of asymptomatic birds. Finally, we used both in situ hybridization and a strand-specific expression assay to localize Poecivirus to beak tissue of AKD-positive individuals and to provide evidence of active viral replication.

CONCLUSION

The data presented here show a strong, statistically significant relationship between Poecivirus infection and AKD, and provide evidence that Poecivirus is indeed an avian virus, infecting and actively replicating in beak tissue of AKD-affected BCCH. Taken together, these data corroborate and extend the evidence for a potential causal association between Poecivirus and AKD in the black-capped chickadee. Poecivirus continues to warrant further investigation as a candidate agent of AKD.

Microbiological identification and analysis of waterfowl livers collected from backyard farms in southern China

In total, 985 livers were collected from 275 backyard waterfowl farms distributed in seven provinces of southern China. The virus that was most commonly isolated was avian influenza virus, with a 12.1% positivity rate. Of the other positive samples, 10.6% tested positive for avian Tembusu virus, 6.8% for duck hepatitis A virus, 3.8% for duck plague virus, 3.4% for Muscovy duck parvovirus, 3.1% for goose parvovirus, 1.0% for mycoplasma and 0.9% for respiratory enteric orphan virus. The bacterium that was most commonly isolated was Escherichia coli, with a 47.1% positivity rate. This survey suggests that backyard waterfowl in southern China could be an important vector for the storage, variation, and transmission of various pathogens.

Complete coding sequence of a novel picorna-like virus in a blackbird infected with Usutu virus

Using random high-throughput RNA sequencing, the complete coding sequence of a novel picorna-like virus (a 9,228-nt contig containing 212,202 reads) was determined from a blackbird (Turdus merula) infected with Usutu virus. This sequence shares only 36% amino acid sequence identity with its closest homolog, arivirus 1, (an unclassified member of the order Picornavirales), and shares its dicistronic genome arrangement. The new virus was therefore tentatively named "blackbird arilivirus" (ari-like virus). The nearly complete genome sequence consists of at least 9,228 nt and contains two open reading frames (ORFs) encoding the nonstructural polyprotein (2235 amino acids) and structural polyprotein (769 amino acids). Two TaqMan RT-qPCR assays specific for ORF1 confirmed the presence of high levels of this novel virus in the original sample. Nucleotide composition analysis suggests that blackbird arilivirus is of dietary (plant) origin.

Clinical Manifestations of Senecavirus A Infection in Neonatal Pigs, Brazil, 2015

We identified new clinical manifestations associated with Senecavirus A infection in neonatal piglets in Brazil in 2015. Immunohistochemical and molecular findings confirmed the association of Senecavirus A with these unusual clinical signs and more deaths. Other possible disease agents investigated were not associated with these illnesses.

Vesicular Disease in 9-Week-Old Pigs Experimentally Infected with Senecavirus A

Senecavirus A has been infrequently associated with vesicular disease in swine since 1988. However, clinical disease has not been reproduced after experimental infection with this virus. We report vesicular disease in 9-week-old pigs after Sencavirus A infection by the intranasal route under experimental conditions.

Detection and complete genome characteristics of Posavirus 1 from pigs in China

Porcine stool-associated RNA virus 1 (Posavirus 1) is a novel member of picornaviruses and first identified from fecal samples of 30-day-old pigs with diarrhea in USA in 2011. To evaluate the existence of Posavirus 1 in swine herds, 118 clinical samples from diarrheal pigs and 31 fecal swabs from healthy pigs were collected and detected by reverse transcription-polymerase chain reaction (RT-PCR) using Posavirus 1-specific primers. Only five fecal samples from diarrheal pigs on two swine farms were positive for Posavirus 1. The complete genome sequences [excluding poly (A) tail] of two representative isolates SDQD-25 and HBTS-11 are determined and consist of 9840 and 9819 nucleotides in length, and encode one putative polyprotein of 3070 and 2952 amino acids, respectively. They share 90.3% homology with each other and 81.3-95.4% homologies with American Posavirus 1 isolates or strains at the nucleotide sequence level. The phylogenetic analysis based on the entire genomes of reference picornavirus strains or isolates showed SDQD-25, HBTS-11 cluster together with American Posavirus 1 isolates or strains, yet are clearly distant from the other picornaviruses. The complete genome sequences of Chinese Posavirus 1 isolates will enrich the information of Posavirus 1 sequence database and further expedite posavirus research on the genetic diversity, epidemiology, and evolution in China.

Picornaviridae-the ever-growing virus family

Picornaviruses are small, nonenveloped, icosahedral RNA viruses with positive-strand polarity. Although the vast majority of picornavirus infections remain asymptomatic, many picornaviruses are important human and animal pathogens and cause diseases that affect the central nervous system, the respiratory and gastrointestinal tracts, heart, liver, pancreas, skin and eye. A stunning increase in the number of newly identified picornaviruses in the past decade has shown that picornaviruses are globally distributed and infect vertebrates of all classes. Moreover, picornaviruses exhibit a surprising diversity of both genome sequences and genome layouts, sometimes challenging the definition of taxonomic relevant criteria. At present, 35 genera comprising 80 species and more than 500 types are acknowledged. Fifteen species within five new and three existing genera have been proposed in 2017, but more than 50 picornaviruses still remain unassigned.

Update on Senecavirus Infection in Pigs

Senecavirus A (SVA) is a positive-sense single-stranded RNA virus that belongs to the Senecavirus genus within the Picornaviridae family. The virus has been silently circulating in pig herds of the USA since 1988. However, cases of senecavirus-associated vesicular disease were reported in Canada in 2007 and in the USA in 2012. Since late 2014 and early 2015, an increasing number of senecavirus outbreaks have been reported in pigs in different producing categories, with this virus being detected in Brazil, China, and Thailand. Considering the novel available data on senecavirus infection and disease, 2015 may be a divisor in the epidemiology of the virus. Among the aspects that reinforce this hypothesis are the geographical distribution of the virus, the affected pig-producing categories, clinical signs associated with the infection, and disease severity. This review presents the current knowledge regarding the senecavirus infection and disease, especially in the last two years. Senecavirus epidemiology, pathogenic potential, host immunological response, diagnosis, and prophylaxis and control measures are addressed. Perspectives are focused on the need for complete evolutionary, epidemiological and pathogenic data and the capability for an immediate diagnosis of senecavirus infection. The health risks inherent in the swine industry cannot be neglected.

A novel RNA-based in situ hybridization to detect Seneca Valley virus in neonatal piglets and sows affected with vesicular disease

Seneca Valley virus (SVV) is the causative agent of an emerging vesicular disease in swine, which is clinically indistinguishable from other vesicular diseases such as foot-and-mouth disease. In addition, SVV has been associated with neonatal mortality in piglets. While a commercial SVV qRT-PCR is available, commercial antibodies are lacking to diagnose SVV infections by immunohistochemistry (IHC). Thus, a novel in situ hybridization technique-RNAscope (ISH) was developed to detect SVVRNA in infected tissues. From a total of 78 samples evaluated, 30 were positive by qRT-PCR and ISH-RNA, including vesicular lesions of affected sows, ulcerative lesions in the tongue of piglets and various other tissues with no evidence of histological lesions. Nineteen samples were negative for SVV by qRT-PCR and ISH-RNA. The Ct values of the qRT-PCR from ISH-RNA positive tissues varied from 12.0 to 32.6 (5.12 x 106 to 5.31 RNA copies/g, respectively). The ISH-RNA technique is an important tool in diagnosing and investigating the pathogenesis of SVV and other emerging pathogens.

Genetic characterization of a second novel picornavirus from an amphibian host, smooth newt (Lissotriton vulgaris)

In this study, a novel picornavirus was identified in faecal samples from smooth newts (Lissotriton vulgaris). The complete genome of picornavirus strain newt/II-5-Pilis/2014/HUN (KX463670) is 7755 nt long with type-IV IRES and has 39.6% aa sequence identity in the protein P1 to the corresponding protein of bat picornavirus (KJ641686, unassigned) and 42.7% and 53.5% aa sequence identity in the 2C and 3CD protein, respectively, to oscivirus (GU182410, genus Oscivirus). Interestingly, the L-protein of newt/II-5-Pilis/2014/HUN has conserved aa motifs that are similar to those found in phosphatase-1 catalytic (PP1C) subunit binding region (pfam10488) proteins. This second amphibian-origin picornavirus could represent a novel species and could be a founding member of a potential novel picornavirus genus.

Novel RNA viruses producing simultaneous covert infections in Ceratitis capitata. Correlations between viral titers and host fitness, and implications for SIT programs

The Mediterranean fruit fly (medfly), Ceratitis capitata is a highly polyphagous pest, which infests multiple species of fruits and vegetables worldwide. In addition to the traditional control with chemical insecticides, sterile insect technique (SIT) has been implemented in integrated programs worldwide, and has become an essential measure for the control of this pest. A key issue for SIT is to release sterile males that are sufficiently competitive with males from the wild population. Using sequence information available in public databases, three novel picornaviruses infecting medflies were discovered and named as C. capitata iflavirus 1 and 2 (CcaIV1 and CcaIV2), and C. capitata noravirus (CcaNV). Additional analyses have revealed the presence of CcaIV2 and CcaNV covertly infecting most of the medfly strains used in the different SIT programs around the world, as well as in field captures in the east of Spain. High viral titers of CcaNV were associated with a reduction in the lifespan of males released to the field for the control of this pest, suggesting the possibility that CcaNV may impair the fitness of sterile flies produced by SIT programs.

Identification of Novel Rosavirus Species That Infects Diverse Rodent Species and Causes Multisystemic Dissemination in Mouse Model

While novel picornaviruses are being discovered in rodents, their host range and pathogenicity are largely unknown. We identified two novel picornaviruses, rosavirus B from the street rat, Norway rat, and rosavirus C from five different wild rat species (chestnut spiny rat, greater bandicoot rat, Indochinese forest rat, roof rat and Coxing's white-bellied rat) in China. Analysis of 13 complete genome sequences showed that “Rosavirus B” and “Rosavirus C” represent two potentially novel picornavirus species infecting different rodents. Though being most closely related to rosavirus A, rosavirus B and C possessed distinct protease cleavage sites and variations in Yn-Xm-AUG sequence in 5’UTR and myristylation site in VP4. Anti-rosavirus B VP1 antibodies were detected in Norway rats, whereas anti-rosavirus C VP1 and neutralizing antibodies were detected in Indochinese forest rats and Coxing's white-bellied rats. While the highest prevalence was observed in Coxing's white-bellied rats by RT-PCR, the detection of rosavirus C from different rat species suggests potential interspecies transmission. Rosavirus C isolated from 3T3 cells causes multisystemic diseases in a mouse model, with high viral loads and positive viral antigen expression in organs of infected mice after oral or intracerebral inoculation. Histological examination revealed alveolar fluid exudation, interstitial infiltration, alveolar fluid exudate and wall thickening in lungs, and hepatocyte degeneration and lymphocytic/monocytic inflammatory infiltrates with giant cell formation in liver sections of sacrificed mice. Since rosavirus A2 has been detected in fecal samples of children, further studies should elucidate the pathogenicity and emergence potential of different rosaviruses.

We identified two novel picornaviruses, rosavirus B and C, infecting street and wild rats respectively in China. While rosavirus B was detected from Norway rats, rosavirus C was detected from five different wild rat species (chestnut spiny rat, greater bandicoot rat, Indochinese forest rat, roof rat and Coxing's white-bellied rat) by RT-PCR. Anti-rosavirus B antibodies were detected in Norway rats, whereas anti-rosavirus C antibodies were detected in Indochinese forest rats and Coxing's white-bellied rats, supporting potential interspecies transmission of rosavirus C. Genome analysis supported the classification of rosavirus B and C as two novel picornavirus species, with genome features distinct from rosavirus A. Rosavirus C isolated from 3T3 cells causes multisystemic diseases in a mouse model, with viruses and pathologies detected in various organs of infected mice after oral or intracerebral inoculation. Our results extend our knowledge on the host range and pathogenicity of rodent picornaviruses.

Molecular epidemiology of senecavirus A associated with vesicular disease in pigs in Brazil

Senecavirus A (SV-A) may cause vesicular disease and neonatal mortality in pigs, and was first detected in Brazil in 2015. Samples including tissues and serum from pigs with suspected vesicular diseases were collected from January to August in 2015 from farms in the states of Minas Gerais, Santa Catarina, Goiás and Rio Grande do Sul, Brazil, and tested for the presence of SV-A by reverse transcriptase PCR. All samples were negative for foot and mouth disease virus, as well as 13 other infectious agents associated with vesicular diseases in pigs. SV-A was detected by PCR in 65/265 (24.5%) specimens. A 530 base pair fragment sequenced from the VP1 protein coding region indicated a high genetic distance from SV-A in other countries, but a common origin among the Brazilian isolates.

Pathogenesis of Korean SapelovirusA in piglets and chicks

Sapelovirus A (SV-A), formerly known as porcine sapelovirus as a member of a new genus Sapelovirus, is known to cause enteritis, pneumonia, polioencephalomyelitis and reproductive disorders in pigs. We have recently identified α2,3-linked sialic acid on GD1a ganglioside as a functional SV-A receptor rich in the cells of pigs and chickens. However, the role of GD1a in viral pathogenesis remains elusive. Here, we demonstrated that a Korean SV-A strain could induce diarrhoea and intestinal pathology in piglets but not in chicks. Moreover, this Korean SV-A strain had mild extra-intestinal tropisms appearing as mild, non-suppurative myelitis, encephalitis and pneumonia in piglets, but not in chicks. By real-time reverse transcription (RT) PCR, higher viral RNA levels were detected in faecal samples than in sera or extra-intestinal organs from virus-inoculated piglets. Immunohistochemistry confirmed that high viral antigens were detected in the epithelial cells of intestines from virus-inoculated piglets but not from chicks. This Korean SV-A strain could bind the cultured cell lines originated from various species, but replication occurred only in cells of porcine origin. These data indicated that this Korean SV-A strain could replicate and induce pathology in piglets but not in chicks, suggesting that additional porcine-specific factors are required for virus entry and replication. In addition, this Korean SV-A strain is enteropathogenic, but could spread to the bloodstream from the gut and disseminate to extra-intestinal organs and tissues. These results will contribute to our understanding of SV-A pathogenesis so that efficient anti-sapelovirus drugs and vaccines could be developed in the future.

Distribution and genetic characterization of Enterovirus G and Sapelovirus A in six Spanish swine herds

The prevalence of Enterovirus G (EV-G) and Sapelovirus A (PSV-1) was investigated in Spanish swine herds by means of cross-sectional studies. Faecal samples from clinically healthy pigs were collected from six farms, and analysed by RT-PCR. The results indicated a high prevalence of EV-G detected in nearly all the animals older than 3 weeks of age. Otherwise, PSV-1 was only detected in 3-week-old piglets from one of the farms. Genetic analyses performed in the VP1 region of the EV-G indicated circulation of diverse strains in the same farm, related to genotypes G1, G2, G3, G4, G6, G9, G12, G13 and G14. Moreover, co-infection of several PSV-1 variants in the same animal was evident, typical of viral quasispecies. Evolutionary pressure analysis indicated that microevolution of PSV-1 seems to be driven by negative selection. This study gives further insights in the epidemiology of EV-G and PSV-1.

Novel picornavirus in domestic rabbits (Oryctolagus cuniculus var. domestica)

Picornaviruses (family Picornaviridae) are small, non-enveloped viruses with positive sense, single-stranded RNA genomes. The numbers of the novel picornavirus species and genera are continuously increasing. Picornaviruses infect numerous vertebrate species from fish to mammals, but have not been identified in a member of the Lagomorpha order (pikas, hares and rabbits). In this study, a novel picornavirus was identified in 16 (28.6%) out of 56 faecal samples collected from clinically healthy rabbits (Oryctolagus cuniculus var. domestica) in two (one commercial and one family farms) of four rabbit farms in Hungary. The 8364 nucleotide (2486 amino acid) long complete genome sequence of strain Rabbit01/2013/HUN (KT325852) has typical picornavirus genome organization with type-V IRES at the 5'UTR, encodes a leader (L) and a single 2A(H-box/NC) proteins, contains a hepatitis-A-virus-like cis-acting replication element (CRE) in the 2A, but it does not contain the sequence forming a "barbell-like" secondary structure in the 3'UTR. Rabbit01/2013/HUN has 52.9%, 52% and 57.2% amino acid identity to corresponding proteins of species Aichivirus A (genus Kobuvirus): to murine Kobuvirus (JF755427) in P1, to canine Kobuvirus (JN387133) in P2 and to feline Kobuvirus (KF831027) in P3, respectively. The sequence and phylogenetic analysis indicated that Rabbit01/2013/HUN represents a novel picornavirus species possibly in genus Kobuvirus. This is the first report of detection of picornavirus in rabbit. Further study is needed to clarify whether this novel picornavirus plays a part in any diseases in domestic or wild rabbits.

[Development and evaluation of an inactivated bivalent vaccine against duck viral hepatitis]

The rapid mutation and widely spread of duck hepatitis A virus (DHAV) lead to the vast economic loss of the duck industry. To prepare and evaluate bivalent inactivated vaccine laboratory products of DHAV, 6 strains were screened from 201 DHAV-1 strains and 38 DHAV-3 strains by using serotype epidemiological analysis in most of the duck factory. Vaccine candidate strains were selected by ELD50 and LD50 tests in the 6 strains. Continuously passaged, the 5th passaged duck embryos bodies grinding fluid was selected as vaccine virus seeds. The virus seeds were treated with formaldehyde and water in oil in water (W/O/W) emulsions, making into three batches of two bivalent inactivated vaccine laboratory products. The safety test, antibody neutralization test, challenged protection and cross immune protection experiment suggested that the vaccines possessed good safety, and neutralizing antibodies were detected at 7th day and the challenged protection rate reached 90% to 100% at the 14th and 21st day. Moreover, immune duration of ducklings lasted more than five weeks. However, cross-immunity protection experiments with DHAV-SH and DHAV-FS only had 20%-30%. The two bivalent inactivated vaccine laboratory products of duck viral hepatitis were effective and reliable, providing a new method as well as a new product for DHAV prevention and control.