RESUMO
The atypical porcine pestivirus (APPV) belongs to the species Pestivirus K of the genus Pestivirus and the family Flaviviridae, and it has been associated with congenital tremor (CT) type A-II in newborn piglets. Although APPV was discovered in 2015, evidence shows that APPV has circulated in pig herds for many years, at least since 1986. Due to the frequently reported outbreaks of CT on different continents, the importance of this virus for global pig production is notable. Since 2015, several studies have been conducted to clarify the association between APPV and CT. However, some findings regarding APPV infection and the measures taken to control and prevent the spread of this virus need to be contextualized to understand the infection better. This review attempts to highlight advances in the understanding of APPV associated with type A-II CT, such as etiology, epidemiology, diagnosis, and control and prevention measures, and also describes the pathophysiology of the infection and its consequences for pig production. Further research still needs to be conducted to elucidate the host's immune response to APPV infection, the control and prevention of this infection, and the possible development of vaccines.
Assuntos
Infecções por Pestivirus/fisiopatologia , Infecções por Pestivirus/veterinária , Pestivirus/classificação , Pestivirus/patogenicidade , Tremor/congênito , Tremor/veterinária , Animais , Animais Recém-Nascidos/virologia , Genoma Viral , Infecções por Pestivirus/epidemiologia , Filogenia , Suínos/virologia , Doenças dos Suínos/epidemiologia , Doenças dos Suínos/virologia , Tremor/virologiaRESUMO
The Pestivirus genus comprises species that affect animal health and productivity worldwide. Members of the Suidae family are hosts for classical swine fever virus (CSFV), an important pathogen tracked by the World Organization for Animal Health (OIE). However, swine are also susceptible to other pestivirus species that can result in disease or compromise CSFV detection. We searched for pestivirus infection in swine sera collected from 320 backyard pig herds in southern Brazil. We used reverse-transcription PCR primers for Bungowannah virus; atypical porcine pestivirus (APPV); and a panpestivirus pair that detects bovine viral diarrhea virus (BVDV)-1, -2, and HoBi-like pestivirus (HoBiPeV), border disease virus (BDV), and CSFV. Two samples were positive using the panpestivirus primer pair and were classified as BVDV-1d and -2a, respectively. Serum samples were tested for virus neutralization against BVDV-1a, -1b, and -2 strains, resulting in 28 (4.4%) positive samples. Of those, 16 samples had the highest titers against BVDV-1a (2), BVDV-1b (5), and BVDV-2 (9). Our results indicate that Bungowannah virus, APPV, CSFV, BDV, and HoBiPeV have not been circulating in these specific backyard swine populations. However, ruminant pestiviruses were detected and must be considered in future pestivirus control programs conducted in Brazil.
Assuntos
Infecções por Pestivirus/veterinária , Pestivirus/isolamento & purificação , Doenças dos Suínos/virologia , Animais , Brasil/epidemiologia , Vírus da Febre Suína Clássica , Pestivirus/classificação , Infecções por Pestivirus/epidemiologia , Infecções por Pestivirus/virologia , Reação em Cadeia da Polimerase , Inquéritos e Questionários , Suínos , Doenças dos Suínos/epidemiologiaRESUMO
Bovine viral diarrhea virus 1, reclassified as Pestivirus A, causes an economically important cattle disease that is distributed worldwide. Pestivirus A may cause persistent infection in that calves excrete the virus throughout their lives, spreading the infection in the herd. Many persistently infected (PI) calves die in the first 2 years of life from mucosal disease (MD) or secondary infections, probably as a consequence of virus-induced immune depression. Here, high-throughput sequencing (HTS) was applied for evaluation of the total virome in sera of (i) PI calves displaying clinically apparent MD (n = 8); (ii) PI calves with no signs of MD (n = 8); and (iii) control, Pestivirus A-free calves (n = 8). All the groups were collected at the same time and from the same herd. Serum samples from calves in each of the groups were pooled, submitted to viral RNA/DNA enrichment, and sequenced by HTS. Viral genomes of Pestivirus A, Ungulate erythroparvovirus 1, bosavirus (BosV), and hypothetical circular Rep-encoding single-stranded DNA (CRESS-DNA) viruses were identified. Specific real-time PCR assays were developed to determine the frequency of occurrence of such viruses in each of the groups. The absolute number of distinct viral genomes detected in both PI calf groups was higher than in the control group, as revealed by higher number of reads, contigs, and genomes, representing a wider range of taxons. Genomes representing members of the family Parvoviridae, such as U. erythroparvovirus 1 and BosV, were most frequently detected in all the three groups of calves. Only in MD-affected PI calves, we found two previously unreported Hypothetical single-stranded DNA genomes clustered along with CRESS-DNA viruses. These findings reveal that parvoviruses were the most frequently detected viral genomes in cattle serum; its frequency of detection bears no statistical correlation with the status of calves in relation to Pestivirus A infection, since clinically normal or MD-affected/non-affected PI calves were infected with similar U. erythroparvovirus 1 genome loads. Moreover, MD-affected PI calves were shown to support viremia of CRESS-DNA viral genomes; however, the meaning of such correlation remains to be established.
Assuntos
Doença das Mucosas por Vírus da Diarreia Viral Bovina/genética , Vírus da Diarreia Viral Bovina Tipo 1/genética , Sequenciamento de Nucleotídeos em Larga Escala , Pestivirus/genética , Animais , Anticorpos Antivirais/sangue , Doença das Mucosas por Vírus da Diarreia Viral Bovina/sangue , Doença das Mucosas por Vírus da Diarreia Viral Bovina/fisiopatologia , Doença das Mucosas por Vírus da Diarreia Viral Bovina/virologia , Bovinos , DNA Viral/genética , Vírus da Diarreia Viral Bovina Tipo 1/isolamento & purificação , Vírus da Diarreia Viral Bovina Tipo 1/patogenicidade , Genoma Viral/genética , Pestivirus/classificação , Pestivirus/isolamento & purificação , Pestivirus/patogenicidade , RNA Viral/genéticaRESUMO
Pestiviruses including Bovine viral diarrhea virus type 1 (BVDV-1), BVDV-2 and Border disease virus (BDV) have been reported in both sheep and cattle populations, together with the HoBi-like, an emerging group of pestiviruses. Pestivirus control programs in the United States have focused on the control of BVDV-1 and 2. The incidence of pestivirus infection in sheep in the United States and the risk of transmission between cattle and sheep populations are unknown. The aim of this study was to perform serological surveillance for pestivirus exposure in sheep from an important sheep producing state in the Unites States, Wyoming. For this, sera from 500 sheep, collected across the state of Wyoming (US) in 2015-2016, were examined by comparative virus neutralization assay against four species/proposed species of pestiviruses: BVDV-1, BVDV-2, BDV and HoBi-like virus. Rates of exposure varied between geographic regions within the state. The overall pestivirus prevalence of antibodies was 5.6%. Antibodies were most frequently detected against BVDV-1 (4%), and the highest antibody titers were also against BVDV-1. Data from this study highlights understanding of the dynamics of sheep pestivirus exposure, consideration of reference strains used for VN assays, transmission patterns, and potential vaccination history should be taken into account in implementation of control measures against pestiviruses in sheep and for successful BVDV control programs in cattle.
Assuntos
Anticorpos Antivirais/sangue , Infecções por Pestivirus/veterinária , Pestivirus/imunologia , Ovinos/imunologia , Animais , Animais Domésticos/imunologia , Animais Domésticos/virologia , Bovinos/virologia , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/transmissão , Doenças dos Bovinos/virologia , Vírus da Diarreia Viral Bovina Tipo 1/imunologia , Vírus da Diarreia Viral Bovina Tipo 2/imunologia , Vírus da Diarreia Viral Bovina/imunologia , Testes de Neutralização , Pestivirus/classificação , Pestivirus/genética , Infecções por Pestivirus/epidemiologia , Infecções por Pestivirus/imunologia , Infecções por Pestivirus/transmissão , Filogenia , Estudos Soroepidemiológicos , Ovinos/virologia , Inquéritos e Questionários , Wyoming/epidemiologiaRESUMO
Recently, a putative new pestivirus species, provisionally named as Atypical Porcine Pestivirus (APPV), was associated with the congenital tremor in piglets in North America and consequently in Europe and Asia. The present research aimed to describe the detection and characterization of APPV employing NS5B gene partial sequencing, gross pathology and histologic examination of piglets displaying congenital tremor from two different farms of Southern Brazil. No gross lesions were observed, and the histological findings revealed moderate vacuolization of the white matter of the cerebellum. RT-PCR followed by DNA sequencing and a phylogenetic analysis confirmed the presence of APPV in samples from the two farms, which the samples were distinct in nature. Phylogenetic reconstruction reinforced the high genetic variability within the APPVs previously reported. This is the first report of APPV in South America suggesting that this new group of viruses may be widespread in swine herds in other countries as it is in Brazil.
Assuntos
Pestivirus/classificação , Doenças dos Suínos/virologia , Tremor/veterinária , Animais , Brasil/epidemiologia , Feminino , Pestivirus/genética , Pestivirus/isolamento & purificação , Filogenia , Análise de Sequência de DNA/veterinária , Suínos , Doenças dos Suínos/congênito , Doenças dos Suínos/epidemiologia , Tremor/congênito , Tremor/epidemiologia , Tremor/virologiaRESUMO
'HoBi'-like virus is an atypical group within the Pestivirus genus that is implicated in economic losses for cattle producers due to both acute and persistent infections. Pestivirus strains exist as quasispecies (swarms of individual viruses) in infected animals and the viral populations making up the quasispecies differ widely in size and diversity in each animal. In the present study the viral quasispecies circulating in persistently infected (PI) calves, generated and maintained under experimental conditions using two different 'HoBi'-like strains, was observed over time. An increase in genetic variability and the development of certain mutations was observed over time. Mutations observed included the loss of a putative N-linked glycosylation site in the E2 region and the change of specific residues in E1/E2. It is hypothesized that these changes may be the results on continued adaption of the pestivirus to individual hosts. This is the first study characterizing variation in the viral swarms of animals persistently infected with HoBi-like viruses over time. Studies of the shifts in PI viral swarms will contribute to our understanding of the host and viral mechanisms that function in the maintenance of pestivirus persistent infections.
Assuntos
Doenças dos Bovinos/virologia , Infecções por Pestivirus/veterinária , Pestivirus/classificação , Pestivirus/genética , Quase-Espécies , Sequência de Aminoácidos , Animais , Bovinos , Variação Genética , Filogenia , RNA Viral , Análise de Sequência de DNA , Proteínas Virais/genética , Proteínas Virais/imunologiaRESUMO
Like other members from the Pestivirus genus, 'HoBi'-like pestiviruses cause economic losses for cattle producers due to both acute and persistent infections. The present study analyzed for the first time PI animals derived from a controlled infection with two different 'HoBi'-like strains where the animals were maintained under conditions where superinfection by other pestiviruses could be excluded. The sequence of the region coding for viral glycoproteins E1/E2 of variants within the swarms of viruses present in the PI calves and two viral inoculums used to generate them were compared. Differences in genetic composition of the viral swarms were observed suggesting that host factors can play a role in genetic variations among PIs. Moreover, PIs generated with the same inoculum showed amino acid substitutions in similar sites of the polyprotein, even in serum from PIs with different quasispecies composition, reinforcing that some specific sites in E2 are important for host adaptation.
Assuntos
Infecções por Pestivirus/virologia , Pestivirus/genética , Filogenia , Proteínas do Envelope Viral/genética , Adaptação Fisiológica , Animais , Bovinos , Clonagem Molecular , Células Epiteliais/patologia , Células Epiteliais/virologia , Expressão Gênica , Pestivirus/classificação , Pestivirus/isolamento & purificação , Cultura Primária de Células , Proteínas Recombinantes/genética , Análise de Sequência de DNA , Conchas Nasais/patologia , Conchas Nasais/virologiaRESUMO
The genus Pestivirus of the family Flaviviridae consists of four recognized species: Bovine viral diarrhoea virus 1 (BVDV-1), Bovine viral diarrhoea virus 2 (BVDV-2), Classical swine fever virus (CSFV) and Border disease virus (BDV). Recently, atypical pestiviruses ('HoBi'-like pestiviruses) were identified in batches of contaminated foetal calf serum and in naturally infected cattle with and without clinical symptoms. Here, we describe the first report of a mucosal disease-like clinical presentation (MD) associated with a 'HoBi'-like pestivirus occurring in a cattle herd. The outbreak was investigated using immunohistochemistry, antibody detection, viral isolation and RT-PCR. The sequence and phylogenetic analysis of 5'NCR, N(pro) and E2 regions of the RT-PCR positive samples showed that four different 'HoBi'-like strains were circulating in the herd. The main clinical signs and lesions were observed in the respiratory and digestive systems, but skin lesions and corneal opacity were also observed. MD characteristic lesions and a pestivirus with cytopathic biotype were detected in one calf. The present study is the first report of a MD like presentation associated with natural infection with 'HoBi'-like pestivirus. This report describes the clinical signs and provides a pathologic framework of an outbreak associated with at least two different 'HoBi'-like strains. Based on these observations, it appears that these atypical pestiviruses are most likely underdiagnosed in Brazilian cattle.
Assuntos
Doenças dos Bovinos/virologia , Surtos de Doenças/veterinária , Infecções por Pestivirus/veterinária , Pestivirus/isolamento & purificação , Animais , Anticorpos Antivirais/sangue , Brasil/epidemiologia , Bovinos , Ensaio de Imunoadsorção Enzimática/veterinária , Imuno-Histoquímica/veterinária , Pestivirus/classificação , Infecções por Pestivirus/diagnóstico , Infecções por Pestivirus/virologia , Filogenia , Análise de Sequência de DNA/veterináriaRESUMO
Viruses from the genus Pestivirus of the family Flaviviridae have a non-segmented, single-stranded RNA genome and can cause diseases in animals from the order Artiodactyla. Homologous recombination is rarely reported in this virus family. To detect possible recombination events, all complete pestivirus genomes that are available in GenBank were screened using distinct algorithms to detect genetic conversions and incongruent phylogenies. Three putative recombinant viruses derived from recombination from different pestivirus subtypes/genogroups were detected: Bovine viral diarrhea virus 1 (BVDV-1) strain 3156, BVDV-2 strain JZ05-1 and Classical swine fever virus (CSFV) strain IND/UK/LAL-290. The present study demonstrated that the pestivirus classification cannot be based only on the analysis of one fragment of the genome because genetic conversions can lead to errors. The designation of the recombinant forms (RF) provides a more informative structure for the nomenclature of the genetic variant. The present work reinforces that homologous recombination occurs in pestivirus populations under natural replication and describes the first evidence of recombination in BVDV-2.