A retrospective cohort study of canid herpesvirus-1 seroprevalence and epidemiology in kennel dogs in Croatia.

Canid alphaherpesvirus-1 (CaHV-1) is an endemic pathogen of dogs worldwide. CaHV-1 is often related to abortions, neonatal mortality, and the death of puppies. Since the first description of the virus in 1965, there has been no generally accepted method for diagnosing CaHV-1. Many authors used the virus neutralisation test (VNT) as a 'reference standard' due to its high specificity. Nasal, vaginal, preputial swabs and serum samples for this study were collected in the population of kennel dogs in Croatia. To determine the optimal VNT protocol, three modifications of the VNT were compared. These modifications were: VNT using native serum samples, VNT using thermally inactivated serum samples, and VNT using thermally inactivated serum samples with the addition of the complement. The correlation between the results of the VNT methods was significant (P < 0.001). Of all three modifications of VNT, the one using native serum samples was the one that increased VNT sensitivity. The overall seroprevalence of CaHV-1 was 32.02%. The PCR did not confirm the CaHV-1 presence in collected swabs. According to analysed anamnestic data, significant risk factors for CaHV-1 infection were: kennel size, attendance at the dog shows, hunt trials, kennel disinfection protocols, and mating. The oestrus cycle had no significant effect on seropositivity. The study results indicate that CaHV-1 spreads horizontally between dams living in kennels and in males during mating. Although there was no correlation between seropositivity and a history of reproductive disorders, significantly more stillborn puppies were recorded in seronegative dames (P < 0.01).

Transcriptomic analysis of differential gene expression reveals an increase in COX2 levels during in vitro canine herpesvirus infection / Análise transcriptômica da expressão gênica diferencial revela um aumento nos níveis de COX2 durante a infecção in vitro por herpesvirus canino

ABSTRACT: Canine herpesvirus (CaHV-1) affects canids worldwide, causing death in neonates and immunosuppressed hosts. Acute infection by CaHV-1 can cause reproductive, respiratory, and neurological problems in adult animals. Viral pathogenesis and host genes expressions during of CaHV-1infection are not clearly understood. In the present study, the transcriptome of canine kidney cell Mardin-Darby (MDCK) infected in vitro with canine herpesvirus was explored. For this, RNA sequencing (RNA-seq) of the samples in different moments during infection was carried out. Subsequently, the transcriptomic analysis genes related to cell activities and process involved to viral cycle infection were evaluated until 32h post-inoculation (pi). Among evaluated genes, was verified a significant and gradative increase of the prostaglandin-endoperoxide synthase 2 (PTGS2) or cyclooxygenase 2 (COX2) gene expression, throughout of infection, though differential gene expression analysis and validated by quantitative reverse transcription PCR (RT-qPCR). High COX2 expression is usually induced in response to inflammation, pathogens or activation of the immune system but can be a viral mechanism to favor viral replication. Thus, COX2 level increase can be a favorable factor for viral infection with Cahv-1 virus and the use of selective COX2 inhibitors may be beneficial for limiting the infection or clinical signs by causing interruption of the viral replication cycle during active infection. Additionally, the regulation genes expression differential verified in this study can contribute to determining important targets for inhibiting canine herpesvirus infection either by cellular or viral mechanisms.

RESUMO: O herpesvírus canino (CaHV-1) afeta os canídeos em todo o mundo, causando morte em neonatos e hospedeiros imunossuprimidos. A infecção aguda por CaHV-1 pode causar problemas reprodutivos, respiratórios e neurológicos em animais adultos. A patogênese viral e expressão de genes hospedeiros durante a infecção por CaHV-1 ainda não são bem compreendidos. No presente estudo, o transcriptoma de células de rim canino Madin-Darby (MDCK) infectadas in vitro com herpesvirus canino foi explorado. Para isso, foi realizado o sequenciamento de RNA (RNA-seq) de amostras coletadas em diferentes momentos durante a infecção. Subsequentemente, a análise transcriptômica dos genes relacionados à atividade celular e aos processos envolvidos no ciclo de infecção do vírus foram avaliadas até 32 horas após a inoculação (pi). Dentre os genes avaliados, constatamos uma elevação significativa e gradativa da expressão da Prostaglandina-endoperoxide sintase 2 (PTGS2) ou ciclooxigenase 2 (COX2), ao longo da infecção viral, foi verificada por análise de expressão gênica diferencial e validada por resultados de transcrição reversa por PCR quantitativo (RT-qPCR). O aumento da expressão de COX2 geralmente é induzida em resposta a inflamação, patógenos ou ativação do sistema imune, mas também pode ser um mecanismo para favorecer a replicação viral. Assim, o aumento do nível de COX2 pode ser um fator favorável à infecção viral pelo vírus CaHV-1 e o uso de inibidores seletivos da COX2 pode ser benéfico para limitar a infecção ou os sinais clínicos, causando a interrupção do ciclo de replicação viral durante a infecção ativa. Além disso, a regulação diferencial da expressão dos genes verificados neste estudo podem contribuir para determinar alvos importantes para inibir a infecção por herpesvírus canino, seja por mecanismos celulares ou virais.

Detection of respiratory viruses in shelter dogs maintained under varying environmental conditions

Abstract Three dog shelters in Rio Grande do Sul were investigated for associations between the occurrence of respiratory viruses and shelter environmental conditions. Nasal secretions randomly collected during the cold season were tested via PCR, and this data collection was followed by nucleotide sequencing of the amplicons. In shelter #1 (poor sanitary and nutritional conditions, high animal density and constant contact between dogs), 78% (58/74) of the nasal samples were positive, 35% (26/74) of which were in single infections and 44% (32/74) of which were in coinfections. Shelters #2 and #3 had satisfactory sanitary and nutritional conditions, outdoors exercise areas (#2) and animal clustering by groups (#3). In shelter #2, 9% (3/35) of the samples were positive for Canine parainfluenza virus (CPIV), and 6% (2/35) were positive for Canid herpesvirus 1 (CaHV-1). In shelter #3, 9% (7/77) of the samples were positive for Canine adenovirus type 2 (CAdV-2), and 1% (1/77) were positive for Canine distemper virus (CDV). The amplicon sequences (CPIV and CDV nucleoprotein gene; CAdV-2 E3 gene; CaHV-1 glycoprotein B gene) showed 94-100% nucleotide identity with GenBank sequences. Our results demonstrate that CPIV, CAdV-2 and CDV are common in dog shelters and that their frequencies appear to be related with environmental and nutritional conditions. These results indicate the need for control/prevention measures, including vaccination and environmental management, to minimize these infections and improve dog health.

Detection of respiratory viruses in shelter dogs maintained under varying environmental conditions.

Three dog shelters in Rio Grande do Sul were investigated for associations between the occurrence of respiratory viruses and shelter environmental conditions. Nasal secretions randomly collected during the cold season were tested via PCR, and this data collection was followed by nucleotide sequencing of the amplicons. In shelter #1 (poor sanitary and nutritional conditions, high animal density and constant contact between dogs), 78% (58/74) of the nasal samples were positive, 35% (26/74) of which were in single infections and 44% (32/74) of which were in coinfections. Shelters #2 and #3 had satisfactory sanitary and nutritional conditions, outdoors exercise areas (#2) and animal clustering by groups (#3). In shelter #2, 9% (3/35) of the samples were positive for Canine parainfluenza virus (CPIV), and 6% (2/35) were positive for Canid herpesvirus 1 (CaHV-1). In shelter #3, 9% (7/77) of the samples were positive for Canine adenovirus type 2 (CAdV-2), and 1% (1/77) were positive for Canine distemper virus (CDV). The amplicon sequences (CPIV and CDV nucleoprotein gene; CAdV-2 E3 gene; CaHV-1 glycoprotein B gene) showed 94-100% nucleotide identity with GenBank sequences. Our results demonstrate that CPIV, CAdV-2 and CDV are common in dog shelters and that their frequencies appear to be related with environmental and nutritional conditions. These results indicate the need for control/prevention measures, including vaccination and environmental management, to minimize these infections and improve dog health.