Epidemiological, clinical and pathological features of canine parvovirus 2c infection in dogs from southern Brazil

Comparative genomics of canine parvovirus in South America: Diversification patterns in local populations

Canine parvovirus (CPV) is a significant pathogen in domestic dogs worldwide, causing a severe and often fatal disease. CPV comprises three antigenic variants (2a, 2b, and 2c) distributed unevenly among several phylogenetic groups. The present study compared genetic variability and evolutionary patterns in South American CPV populations. We collected samples from puppies suspected of CPV infection in the neighboring Argentina and Uruguay. Antigenic variants were preliminarily characterized using PCR-RFLP and partial vp2 sequencing. Samples collected in Argentina during 2008-2018 were mainly of the 2c variant. In the Uruguayan strains (2012-2019), the 2a variant wholly replaced the 2c from 2014. Full-length coding genome and vp2 sequences were compared with global strains. The 2c and 2a strains fell by phylogenetic analysis into two phylogroups (Europe I and Asia I). The 2c strains from Argentina and Uruguay clustered in the Europe I group, with strains from America, Europe, Asia, and Oceania. Europe I is widely distributed in South America in the dog population and is also being detected in the wildlife population. The 2a strains from Uruguay formed the distinct Asia I group with strains from Asia, Africa, America, and Oceania. This Asia I group is increasing its distribution in South America and worldwide. Our research reveals high genetic variability in adjacent synchronic samples and different evolutionary patterns in South American CPV. We also highlight the importance of ancestral migrations and local diversification in the evolution of global CPV strains.

Canine parvovirus type 2 (CPV-2) serological and molecular patterns in dogs with viral gastroenteritis from southern Brazil

Canine Parvovirus type 2 (CPV-2) is a highly contagious virus that can cause severe systemic disease with gastroenteric symptoms in dogs, particularly in young puppies. Originating from the feline parvovirus in the late 1970s, it swiftly propagated globally, instigating a pandemic in dogs. Despite vaccination advancements, CPV-2 remains a substantial challenge for veterinary professionals and pet owners. This study aimed to contribute knowledge about the current situation of CPV-2 among dogs in southern Brazil. In this study, the sera of 125 dogs (mostly with gastroenteritis symptoms) were screened for antibodies against CPV-2 and their faeces for the virus itself. The results showed that 40% (50/125) of dogs were infected with CPV-2. Most animals (65.5%) had previously been exposed to CPV-2 (with serotitres equal or above 1:40), and only 37.6% had protective antibody titres equal or above 1:80. The findings have also demonstrated that vaccination against CPV-2 significantly reduced the risk of infection, with positive cases decreasing from 56.9% (unvaccinated) to 2.0% (fully vaccinated). Furthermore, the prevalence of CPV-2 decreased as dogs aged, with younger dogs and those with an incomplete or non-existent vaccination history at the highest risk of infection. In conclusion, this study provides valuable insight into the prevalence and risk factors associated with CPV-2 infection in dogs in southern Brazil, thereby providing valuable knowledge for the improvement of veterinary care and pet health.

Antioxidant supplementation during treatment of outpatient dogs with parvovirus enteritis ameliorates oxidative stress and attenuates intestinal injury: A randomized controlled trial

A prospective randomized controlled clinical study was conducted to determine whether antioxidant supplementation as an adjunct therapy alters hemogram, oxidative stress, serum intestinal fatty acid binding protein-2 (IFABP-2) level, fecal viral load, clinical score (CS) and survivability in outpatient canine parvovirus enteritis (CPVE) dogs. The dogs with CPVE were randomized to one of the five treatment groups: supportive treatment (ST) alone, ST with N-acetylcysteine (ST+NAC), resveratrol (ST+RES), coenzyme Q10 (ST+CoQ10) or ascorbic acid (ST+AA). The primary outcome measures were reduction of CS and fecal HA titre, and enhancement of survivability. Secondary outcome measures were reduction of oxidative stress indices and IFABP-2 level from day 0 to day 7. The mean CS and HA titre were significantly (P < 0.05) decreased from day 0 to 7 in ST and all antioxidant groups. The supplementations of NAC, RES and AA along with ST markedly (P < 0.05) reduced the concentrations of malondialdehyde, nitric oxide and IFABP-2 on day 7 as compared to ST alone. Additionally, NAC and RES supplementations markedly (P < 0.05) improved the total leukocyte count and neutrophil count in CPVE-affected dogs. NAC and RES could serve as better antioxidants for the amelioration of oxidative stress in CPVE but, the antioxidants did not confer any additional benefits in reduction of CS, fecal HA tire, or survivability when compared with ST alone.

Experimental study of tropism of cultivated canine parvovirus in the immunogenesis organs of puppies

The immune system unites the organs and the tissues that protect the organism against genetically alien cells or substances entering the organism from the environment. Canine parvovirus is an etiologic agent of hemorrhagic gastroenteritis and causes a significant problem for veterinary medicine due to high level of morbidity and mortality, mostly among dogs, because of fast progression without immune-complement response. In this study, based on the results of our clinical, virological, histological, histochemical and morphological assays, we determined the pathogenetic role of parvovirus in sick dogs experimentally infected per os, specifically with isolated canine parvovirus (Antaeus) with titer of infectious activity equaling 3.80 ± 0.008 lg TCID50/cm, cultivated on heterological cell cultures. This allowed us to clarify, add to and generalize the data on the pathogenesis of the disease and determine pathohistological and histochemical changes in the immunogenesis, since the studied virus expresses immune-suppressive properties, leading to ruination of the locomotor ability of the organism and fast lethal outcome. The study of pathomorphological changes was carried out using pathoanatomical and histologic methods. Pathoanatomical material from the autopsy of puppies aged 45 days was fixed in 10% aqueous solution of neutral formaline and embedded in paraffin. Having parvoviral infection, dogs experience pathomorphologic changes in immune-complement organs, indicating inhibition of the immunogenesis function during an infectious disease of viral etiology. In the immunogenesis organs of puppies with the experimental reconstruction of parvoviral enteritis, we microscopically determined the following: edema of the cortex and medulla, disorganization of thymic corpuscules, and impairment of processes of differentiation of lymphocytes in the cortex and medulla of the thymic lobules; edema and large areas of accumulation of hemosiderin in the spleen as a result of breakdown of large amount of erythrocytes; acute inflammatory hyperemia of the parenchyma, swelling of sinuses, serous and serous-hemorrhagic lymphadenitis in lymph nodes. The complex of histologic changes in the immune protection organs, which we found in the conditions of experimental reconstruction of parvoviral infection, can be considered a distinct criterion for pathomorphologic differentiation diagnostics of parvoviral enteritis in dogs.

Canine parvovirus-2: An Emerging Threat to Young Pets

Canine parvovirus-2 (CPV-2) is a highly contagious and key enteropathogen affecting the canine population around the globe by causing canine parvoviral enteritis (CPVE) and vomition. CPVE is one of the the leading causes of morbidity and mortality in puppies and young dogs. Over the years, five distinct antigenic variants of CPV-2, namely CPV-2a, CPV-2b, new CPV-2a, new CPV-2b, and CPV-2c, have emerged throughout the world. CPV-2 infects a diverse range of wild animals, and the newer variants of CPV-2 have expanded their host range to include felines. Despite the availability of highly specific diagnostics and efficacious vaccines, CPV-2 outbreaks have been reported globally due to the emergence of newer antigenic variants, expansion of the viral host range, and vaccination failures. The present chapter describes the latest information pertaining to virus properties and replication, disease manifestations in animals, and an additional recent updates on diagnostic, prevention and control strategies of CPV-2.

Assessment of certain biomarkers for predicting survival in response to treatment in dogs naturally infected with canine parvovirus

Canine parvovirus (CPV) enteritis is an important cause of morbidity and mortality in puppies despite aggressive treatment. Identification of reliable biomarkers for CPV enteritis is essential to determine the severity, duration of hospitalization, and predict the clinical outcome. Meanwhile, the biomarkers will assist in decision-making with clients about the further course of treatment or euthanasia. The present study was conducted to evaluate the changes of total leukocyte count (TLC), neutrophil count, and serum concentrations of creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH), intestinal fatty acid binding protein-2 (IFABP-2), albumin, ceruloplasmin (Cp), cortisol, free triiodothyronine (FT₃) and free thyroxine (FT₄) in survivors and non-survivors as a predictor of the clinical outcome. Marked leukopenia, neutropenia, hypoalbuminemia, elevated levels of CK-MB, IFABP-2, Cp, and cortisol were noticed in CPV-infected dogs than healthy dogs but, LDH, FT₃ and FT₄ concentrations did not differ significantly. The CPV-infected non-survivors had persistent leukopenia, neutropenia and elevated CK-MB, IFABP-2, Cp and cortisol concentrations at 72 h of commencement of treatment. In CPV-infected survivors, TLC and neutrophil count were significantly increased, and CK-MB, IFABP-2, Cp and cortisol concentrations were significantly decreased at 72 h of commencement of treatment. The positive predictive values (PPVs) for survival using cut-off value of TLC (>3.2 × 10³/μL), neutrophil count (>1.65 × 10³/μL), CK-MB (≤234.50 U/L), IFABP-2 (≤7.61 ng/mL), Cp (≤0.605 g/L) and cortisol (≤16.90 ng/mL) were determined as 89.47%, 88.88%, 94.73%, 93.33%, 94.44% and 89.47%, respectively with better area under receiver operating characteristic (ROC) curve as well as sensitivity. The magnitude of decrease in TLC, neutrophil count, and increase in CK-MB, IFABP-2, Cp and cortisol concentrations at 72 h of initiation of treatment in dogs with parvoviral enteritis could be useful indicators for the prognosis of the disease. Based on sensitivity (%) and specificity (%) from ROC curve analysis and PPV (%), it is concluded that serum CK-MB concentration will serve as the most useful biomarker followed by Cp and absolute neutrophil count.

Neorickettsia helminthoeca associated lymphoid, enteric, and pulmonary lesions in dogs from Southern Brazil: An immunohistochemical study

Neorickettsia helminthoeca (NH), the agent of salmon poisoning disease or canine neorickettiosis (CN), is a bacterial endosymbiont of the nematode Nanophyetus salmincola, and infections are spreading among specific fish-eating mammalians. This article describes the pathologic and immunohistochemical findings associated with spontaneous NH-induced infections in dogs from Southern Brazil. The principal pathologic findings were hypertrophy of Peyer patches and lymphadenopathy with lymphocytic proliferation, chronic interstitial pneumonia, and chronic enteritis associated with positive intralesional immunoreactivity to antigens of NH within macrophages and histiocytes. Positive immunoreactivity against canine parvovirus-2 (CPV-2) or/and canine distemper virus was not detected in the evaluated intestinal segments or in the samples from the cerebellum and lungs, respectively, from the dogs evaluated. These findings demonstrated that NH was involved in the enteric, pulmonary, and lymphoid lesions herein described, and provide additional information to confirm the occurrence of this bacterial endosymbiont within this geographical location. It is proposed that chronic pneumonia should be considered as a pathologic manifestation of NH-induced infections. Additionally, our results show that the occurrences of CN seem to be underdiagnosed in Southern Brazil due to the confusion with the incidence of CPV-2.

New variants of canine parvovirus in dogs in southern Brazil

Carnivore protoparvovirus 1 (canine parvovirus 2, CPV-2) has undergone a rapid evolution through mutations in the capsid protein VP2, giving rise to variants associated with unique clinicopathological and immunological features. VP2 is a major capsid protein involved in key steps of virus biology, including interactions with cellular receptors and with the immune system. This study analyzed the complete VP2 coding sequence of 38 CPV-2 isolates obtained from dogs with clinical parvovirosis in southern Brazil. Amplicons encompassing the whole VP2 coding region were subjected to nucleotide sequencing, and predicted amino acid sequences were analyzed to identify molecular markers of viral variants. Viral variants were classified as CPV-2a, -2b or -2c based on the presence of the amino acid Asn, Asp or Glu, respectively, at VP2 residue 426. Amino acid sequence analysis identified 20 CPV-2c and four CPV-2b isolates. Eleven viruses were identified as New CPV-2a, two as New CPV-2b, and one resembled the original CPV-2 and was designated CPV-2-like. In addition to the mutation at amino acid 426 of VP2, new 2a/2b variants containing a Ser297Ala mutation at residue 297 were identified. CPV-2-like samples contained some mutations that were also present in the original CPV-2 isolate, including as Leu, Thr, Ala and Asp at residues 87, 101, 300 and 305, respectively. The New CPV-2a isolates had three additional mutations (Phe267Tyr, Tyr324Ile and Thr440Ala) associated with selective pressure and development of disease in vaccinated dogs. The resemblance of the CPV-2-like isolate to CPV-2 suggests reemergence of CPV-2 and/or evolution from vaccine strains. Phylogenetic analysis grouped the variants with their respective reference strains, in general, according to amino acid changes. These results demonstrate the high VP2 diversity of CPV circulating in dogs in southern Brazil and indicate the emergence of new viral variants that differ markedly from the current vaccine strains.

Isolation and genome characterization of canine parvovirus type 2c in Brazil

This study focused on the isolation and characterization of parvovirus in an infected dog in midwestern Brazil. Non-enveloped icosahedral parvovirus-like particles were isolated in CRFK cells and were allocated to a clade comprised of strains of CPV-2c, based on genome analysis. This is the first isolate of CPV-2c genomically characterized in Brazil.