Carnivore Protoparvovirus-1 Associated With an Outbreak of Hemorrhagic Gastroenteritis in Small Indian Civets

Carnivore chaphamaparvovirus-1 (CaChPV-1) infection in diarrheic dogs reveals viral endotheliotropism in intestine and lung

BACKGROUND

Carnivore chaphamaparvovirus-1 (CaChPV-1) is a parvovirus identified in dogs and association of infection with diarrhea is controversial. Information on whether tissue tropism persists is lacking.

OBJECTIVES

To determine the disease association of CaChPV-1 in dogs with diarrhea and to investigate viral tropism and genetic diversity.

ANIMALS AND METHODS

CaChPV-1 infection was investigated in five recently deceased puppies and designed a retrospective study to determine whether the presence of CaChPV-1 is associated with diarrhea. The retrospective study was conducted in 137 intestinal tissue samples and 168 fecal samples obtained from 305 dogs. CaChPV-1 tissue localization was determined using in situ hybridization, and CaChPV-1 complete genomes obtained from dead puppies and retrospective study were sequenced and analyzed.

RESULTS

CaChPV-1 was detected in 6.56% (20/305) of tested dogs, including 14 diarrheic- and 6 non-diarrheic dogs, and was significant in puppies with diarrhea (p = 0.048). Among the CaChPV-1-positive diarrheic dogs, one sample was obtained from intestinal tissue and 13 samples were fecal samples. However, six CaChPV-1 positive non-diarrheic dogs were based on fecal samples but not on intestinal tissue. Within the age range, the presence of CaChPV-1 was significant in puppies (p < 0.00001) and was mainly localized in the stromal and endothelial cells of intestinal villi and pulmonary alveoli. Phylogenetic analysis indicated genetic diversity of CaChPV-1 Thai strains that were mostly clustered within the sequences found in China.

CONCLUSIONS

Although definitive pathogenesis of CaChPV-1 remains undetermined, this study provides evidence supporting that CaChPV-1 localizes in canine cells and could play a potential role as an enteric pathogen.

Small but mighty: old and new parvoviruses of veterinary significance

In line with the Latin expression "sed parva forti" meaning "small but mighty," the family Parvoviridae contains many of the smallest known viruses, some of which result in fatal or debilitating infections. In recent years, advances in metagenomic viral discovery techniques have dramatically increased the identification of novel parvoviruses in both diseased and healthy individuals. While some of these discoveries have solved etiologic mysteries of well-described diseases in animals, many of the newly discovered parvoviruses appear to cause mild or no disease, or disease associations remain to be established. With the increased use of animal parvoviruses as vectors for gene therapy and oncolytic treatments in humans, it becomes all the more important to understand the diversity, pathogenic potential, and evolution of this diverse family of viruses. In this review, we discuss parvoviruses infecting vertebrate animals, with a special focus on pathogens of veterinary significance and viruses discovered within the last four years.

Molecular and Pathological Investigations of Selected Viral Neuropathogens in Rabies-Negative Brains of Cats and Dogs Revealed Neurotropism of Carnivore Protoparvovirus-1

Throughout the year, the Thai Red Cross Society (TRCS), Bangkok, Thailand, received more than 100 animals that died of suspected rabies due to neurological clinical signs. Concerning the role of viral infection in the brain in the outcome of neurological diseases in cats and dogs, a comprehensive study was conducted of 107 brain samples of cats and dogs submitted to the TRCS from August 2019 to August 2020. Selective molecular screening using conventional polymerase chain reaction (PCR) and reverse transcription PCR targeting nine viral pathogens was employed in addition to histopathological investigations. The results showed that carnivore protoparvovirus-1 (CPPV-1) was detected in 18.69% of the cats and dogs sampled (20/107). These results were found in young and old animals; the brain tissue did not show any pathological changes suggesting encephalitis or cerebellar hypoplasia. In addition, feline calicivirus, feline alphaherpesvirus-1, feline coronavirus, and canine distemper virus were also detected, providing a broader range of potential viral infections to consider in the clinical manifestation of neurological disorders in companion animals. The detection of all pathogens was confirmed by the localization of each viral antigen in various resident brain cells using immunohistochemistry. A unique L582S amino acid substitution of the non-structural protein 1 gene coding sequence, speculated to be associated with the neurotropism of CPPV-1 in cats and dogs, was not evident. In conclusion, this study revealed a noteworthy neurotropism of CPPV-1 in both cats and dogs without neurological lesions.

Canine bocavirus-2 infection and its possible association with encephalopathy in domestic dogs

Canine bocaviruses (CBoVs) have been recognized as pathogens associated with intestinal diseases. Hematogenous spreading caused by CBoV has been documented and may potentiate the virus entry across the blood-brain barrier to initiate a brain infection. This study focused attention on CBoV detection in cases of encepahlopathy and attempted to determine its viral localization. A total of 107 dog brains that histologically exhibited encephalopathy (ED) were investigated for the presence of CBoVs using polymerase chain reaction (PCR). Thirty-three histologically normal brain samples from dogs were used as a control group (CD). CBoV-2 was detected in 15 ED dogs (14.02%) but not in CD dogs (p = 0.02), while no CBoV-1 and -3 were detected. Among the CBoV-2 positive dogs, brain histological changes were characterized by nonsuppurative encephalitis, with inclusion body-like materials in some brains. In situ hybridization (ISH) and transmission electron microscopy (TEM) confirmed the presence of CBoV-2 viral particles in glial cells, supporting neurotropism of this virus. ISH signals were also detected in the intestines, lymphoid organs, and the heart, suggesting both enteral and parenteral infections of this virus. Whole genome characterization and evolutionary analysis revealed genetic diversity of CBoV-2 sequences and it was varying among the different countries where the virus was detected. This study points to a possible association of CBoV-2 with encephalopathy in dogs. It also highlights the genetic diversity and cellular tropism of this virus.

Molecular Characteristics of Carnivore protoparvovirus 1 with High Sequence Similarity between Wild and Domestic Carnivores in Taiwan

Carnivore protoparvovirus 1 (CPPV-1) is a DNA virus causing gastrointestinal disease and immunosuppression in various terrestrial carnivores. Domestic dogs and cats are considered the primary CPPV-1 reservoirs. The habitat overlap of wild carnivores and free-roaming dogs increases the threat of CPPV-1 transmission between them. This study explored the CPPV-1 distribution among wild carnivores in Taiwan through PCR screening and compared the partial capsid protein (VP2) gene sequences from wild and domestic carnivores. In total, 181 samples were collected from 32 masked palm civets (Paguma larvata), 63 Chinese ferret badgers (Melogale moschata), and 86 crab-eating mongooses (Herpestes urva), from 2015 to 2019 were screened for CPPV-1. The average prevalence of CPPV-1 was 17.7% (32/181), with the highest prevalence in masked palm civets (37.5%). In addition, a masked palm civet was coinfected with two CPPV-1 strains. Among the 33 partial VP2 gene sequences, 23 were identical to the sequences amplified from domestic dogs and cats in Asia, and the remaining 10 were identified for the first time. This study supported the circulation of CPPV-1 strains with the same genomic features as domestic carnivores that are also in wild carnivores from the same environment in Taiwan by molecular data. Therefore, further population control and health management of free-roaming domestic carnivores are recommended.

Natural infection of parvovirus in wild fishing cats (Prionailurus viverrinus) reveals extant viral localization in kidneys

Carnivore protoparvovirus-1 (CPPV-1), a viral species containing feline panleukopenia virus (FPV) and canine parvovirus (CPV) variants, are widely spread among domestic and wild carnivores causing systemic fatal diseases. Wild fishing cats (Prionailurus viverrinus), a globally vulnerable species, have been found dead. Postmortem examination of the carcasses revealed lesions in intestine, spleen and kidney. CPPV-1 antigen identification in these tissues, using polymerase chain reaction (PCR) and immunohistochemistry (IHC), supported the infection by the virus. PCR- and IHC-positivity in kidney tissues revealed atypical localization of the virus while in situ hybridization (ISH) and transmission electron microscopy (TEM) with the pop-off technique confirmed the first description of viral localization in kidneys. Complete genome characterization and deduced amino acid analysis of the obtained CPPV-1 from the fishing cats revealed FPV as a causative agent. The detected FPV sequences showed amino acid mutations at I566M and M569R in the capsid protein. Phylogenetic and evolutionary analyses of complete coding genome sequences revealed that the fishing cat CPPV-1 genomes are genetically clustered to the FPV genomes isolated from domestic cats in Thailand. Since the 1970s, these genomes have also been shown to share a genetic evolution with Chinese FPV strains. This study is the first evidence of CPPV-1 infection in fishing cats and it is the first to show its localization in the kidneys. These findings support the multi-host range of this parvovirus and suggest fatal CPPV-1 infections may result in other vulnerable wild carnivores.

Genetic and phylogenetic analysis of canine bufavirus from Anhui Province, Eastern China

Bufavirus is a novel virus associated with canine gastroenteritis. Three strains of bufavirus were first detected in dog feces collected from Anhui province in Eastern China. The near-complete genome sequences were amplified. Sequence alignment showed 98.3-99.5% homology between the three bufavirus strains and reference strains. Phylogenetic analysis showed the distributed viruses forming a cluster of close relationships. Selective pressure analysis of the VP2 region indicated that the canine bufavirus (CBuV) was mainly subject to negative selection during evolution. The negative selection site was located on the residue of B-cell epitopes, indicating minimal change to the virus's immunogenicity. Since this is the first report of CBuV circulating in Anhui Province, this study will provide further understanding of the phylogenetic and molecular characteristics of CBuV and serve as a reference for prevention and vaccine development.