Prevalence of astrovirus and parvovirus in Japanese domestic cats

China-origin G1 group isolate FPV072 exhibits higher infectivity and pathogenicity than G2 group isolate FPV027

Introduction

Feline parvovirus (FPV), a single-stranded DNA virus, is accountable for causing feline panleukopenia, a highly contagious and often lethal disease that primarily affects cats. The epidemiology prevalence and pathogenicity of FPV in certain regions of China, however, remains unclear. The aim of this research was to investigate the epidemiology of FPV in different regions of China in 2021 and compare its infectivity and pathogenicity.

Methods

In this research, a total of 36 FPV strains were obtained from diverse regions across China. Phylogenetic analysis was performed based on the VP2 and NS1 sequences, and two representative strains, FPV027 and FPV072, which belonged to different branches, were selected for comparative assessment of infectivity and pathogenicity.

Results and discussion

The results revealed that all strains were phylogenetically classified into two groups, G1 and G2, with a higher prevalence of G1 strains in China. Both in vitro and in vivo experiments demonstrated that FPV072 (G1 group) exhibited enhanced infectivity and pathogenicity compared to FPV027 (G2 Group). The structural alignment of the VP2 protein between the two viruses revealed mutations in residues 91, 232, and 300 that may contribute to differences in infectivity and pathogenicity. The findings from these observations will contribute significantly to the overall understanding of the molecular epidemiology of FPV in China and facilitate the development of an effective FPV vaccine.

Worldwide prevalence and genotype distribution of human astrovirus in gastroenteritis patients: A systematic review and meta-analysis

AIM

Human astrovirus (HAstV) is an important causative agent of gastroenteritis in humans, which mainly infects young children and the elderly. The goal of this study was to conduct a meta-analytic review of the prevalence of HAstV amongst patients with gastroenteritis, and to shed light on the connection between HAstV infection and gastroenteritis.

METHODS

Systematic literature searches were conducted to identify all potentially relevant studies recorded up to April 8th, 2022. For study weighting, the inverse variance method was employed and the random-effects model was applied to evaluate data. For case-control studies, the pooled odds ratio (OR) and 95% confidence interval (CI) were calculated to establish the relationship between HAstV infection and gastroenteritis.

RESULTS

Among 302423 gastroenteritis patients from 69 different countries, the overall pooled prevalence of HAstV infection was 3.48% (95% CI: 3.11%-3.89%). Case-control approach was used in 39 investigations, and the overall prevalence of HAstV infection among the 11342 healthy controls was 2.01% (95% CI: 1.40%-2.89%). Gastroenteritis and HAstV infection were associated with a pooled OR of 2.16 (95% CI: 1.72-2.71; P < 0.0001; I² = 33.7%). The most commonly found HAstV genotypes in gastroenteritis patients were HAstV1 (62.18%), HAstV7 (33.33%), and HAstV-MLB1 (17.43%).

CONCLUSION

The frequency of HAstV infection was the highest in children under the age of five, and in developing countries. The prevalence rate of HAstV was not influenced by gender. Semi-nested and nested RT-PCR were highly sensitive assays for detecting HAstV infections.

Molecular characterization of carnivore protoparvovirus strains circulating in cats in Turkey

ABSTRACT: Cats are susceptible to feline panleukopenia virus (FPV) and canine parvovirus type 2 (CPV-2). Therefore, coinfection and superinfection with multiple parvovirus strains may occur, resulting in high heterogeneity and recombination. Considering the importance of cats as a potential source of genetic diversity for parvoviruses, we investigated the frequency of parvovirus infection in cats using their blood and fecal samples and performed molecular characterization of parvovirus strains circulating in cat populations. Accordingly, the fecal and blood samples of 60 cats with gastroenteritis symptoms were collected from Turkey’s Burdur, Isparta, and Izmit provinces. Of these 15 fecal samples tested as parvovirus-positive by PCR, 14 were confirmed to have been infected with true FPV strains by sequencing analysis. Through the phylogeny analysis, those were located in the FPV cluster, closely related to CPV-2, and one was discriminated in the CPV-2b cluster. Additionally, sequence analysis of the VP2 gene of CPV and FPV revealed that the FPV strains detected in Turkey and the vaccine strains were highly related to each other, with a nucleotide identity of 97.7- 100%. Furthermore, 13 variable positions were detected in VP2 of the field and reference FPV strains. Three synonymous mutations were determined in the VP2 gene. Some amino acid mutations in the VP2 protein-affected sites were considered responsible for the virus’s biological and antigenic properties. The partial sequence analysis of the VP2 gene revealed that four FPV strains detected in Turkey have a single nucleotide change from T to G at the amino acid position 384 between the nucleotides 3939-3941, which was reported for the first time. Therefore, these four isolates formed a different branch in the phylogenetic tree. The results suggest that both FPV and CPV-2b strains are circulating in domestic cats in Turkey and cats should be considered as potential sources of new parvovirus variants for cats, dogs and other animals.

Development of a TaqMan-based multiplex real-time PCR for simultaneous detection of four feline diarrhea-associated viruses

Since their recent discovery, the prevalence of novel feline enteric viruses, including feline bocavirus 1 (FBoV-1), feline astrovirus (FeAstV), and feline kobuvirus (FeKoV), has been reported in China. Co-infections of these viruses with feline parvovirus (FPV) are common causes of diarrhea in cats. Viral co-infections are difficult to identify because of their non-specific clinical signs. To detect and identify these viruses, a quick and specific pathogen-testing approach is required. Here, we establish a real-time PCR (qPCR) based on multiple TaqMan probes for the simultaneous detection of FBoV-1, FeAstV, FeKoV, and FPV. Specific primers and TaqMan fluorescent probes were designed to ensure specificity. The results showed that the detection limit of single qPCR was up to 10 copies, and the detection limit of multiplex qPCR was up to 100 copies, with correlation coefficients >0.995 in all cases. Clinical sample detection revealed a 25.19% (34/135) total rate of co-infection among the viruses and a 1.48% (2/135) quadruple infection rate. Thus, this multiplex qPCR approach can serve as a quick, sensitive, and specific diagnostic tool for FBoV-1, FeAstV, FeKoV, and FPV identification, and it may be utilized for routine surveillance of these emerging and reemerging feline enteric viruses.

First detection of feline bocaparvovirus 2 and feline chaphamaparvovirus in healthy cats in Turkey

The pet cat’s population and the number of viruses that infect them are increasing worldwide. Recently, feline chaphamaparvovirus (FeChPV, also called fechavirus) and feline bocaparvovirus (FBoV) infections, which are novel parvovirus species, have been reported in cats from different geographic regions. Here, we investigated FBoV 1–3 and FeChPVs in healthy cats in Turkey using PCR, where nuclear phosphoprotein 1 (NP1) is targeted for FBoV and NP for FeChPV. For this purpose, oropharygeal swabs were obtained from 70 healthy cats with different housing status from June 15 to December 1, 2020. After PCR screening tests, six out of 70 cats (5/47 shelter cats; 1/23 domestic cats) were found to be positive for FBOV, while two were positive for FeChPV (1/47 shelter cats; 1/23 domestic cats). No cat was found in which both viruses were detected. The nucleotide (nt) sequence comparison in the 310 base pair (bp) NP gene of the two FeChPVs identified in this study shared a high identity with each other (95.0% nt and 99% aa identities) and with previously reported FeChPVs (92.4–97.1% nt and 98.1–99.0% aa identities), including 313R/2019/ITA, 49E/2019/ITA, VRI_849, 284R/2019/ITA, and IDEXX-1. Here, the near-full length (1489 nt, 495 amino acids-aa) of the VP2 gene of the FechaV/Tur-2020/68 isolate obtained from the study was also sequenced. The nt and aa identity ratio of this isolate with other FeChPVs was 98.0–98.5%-96–96.5%, respectively. Sequences of the 465 bp NP1 gene of the six Turkish FBoV strains shared high identities with each other (99.6–100% nt and 99.3–100% aa identities) and with those of FBoV-2 strains (97.8–99.1% nt and 98.0–100% aa identities), including 16SY0701, 17CC0505-BoV2, HFXA-6, and POR1. All FBoVs detected in this study were classified as genotype 2, similar to the study conducted in Japan and Portugal. Here, the NS1 (partial), NP1, VP1 and VP2 gene of the FBoV-2/TUR/2020–14 strain obtained from the study were also sequenced and the nt and aa sequences showed high identities to the above-mentioned FBoV-2 strain/isolates (> 96%, except for the aa ratio of strain 16SY0701). In conclusion, this study shows that FBoV and FeChPV are present in healthy cats in Turkey, and these viruses can be detected from oropharyngeal swabs. Our findings contribute to further investigation of the prevalence, genotype distribution, and genetic diversity of Turkish FBoVs and FeChPVs, adding to the molecular epidemiology of FBoV and FeChPVs worldwide.

Beyond the Gastrointestinal Tract: The Emerging and Diverse Tissue Tropisms of Astroviruses

Astroviruses are single stranded, positive-sense RNA viruses that have been historically associated with diseases of the gastrointestinal tract of vertebrates, including humans. However, there is now a multitude of evidence demonstrating the capacity of these viruses to cause extraintestinal diseases. The most striking causal relationship is neurological diseases in humans, cattle, pigs, and other mammals, caused by astrovirus infection. Astroviruses have also been associated with disseminated infections, localized disease of the liver or kidneys, and there is increasing evidence suggesting a potential tropism to the respiratory tract. This review will discuss the current understanding of the tissue tropisms for astroviruses and their emerging capacity to cause disease in multiple organ systems.