Prevalence of Feline Coronavirus Shedding in German Catteries and Associated Risk Factors

Antiviral activity of Vigna radiata extract against feline coronavirus in vitro

Feline infectious peritonitis (FIP) is a fatal illness caused by a mutated feline coronavirus (FCoV). This disease is characterized by its complexity, resulting from systemic infection, antibody-dependent enhancement (ADE), and challenges in accessing effective therapeutics. Extract derived from Vigna radiata (L.) R. Wilczek (VRE) exhibits various pharmacological effects, including antiviral activity. This study aimed to investigate the antiviral potential of VRE against FCoV, addressing the urgent need to advance the treatment of FIP. We explored the anti-FCoV activity, antiviral mechanism, and combinational application of VRE by means of in vitro antiviral assays. Our findings reveal that VRE effectively inhibited the cytopathic effect induced by FCoV, reduced viral proliferation, and downregulated spike protein expression. Moreover, VRE blocked FCoV in the early and late infection stages and was effective under in vitro ADE infection. Notably, when combined with VRE, the polymerase inhibitor GS-441524 or protease inhibitor GC376 suppressed FCoV more effectively than monotherapy. In conclusion, this study characterizes the antiviral property of VRE against FCoV in vitro, and VRE possesses therapeutic potential for FCoV treatment.

Prevalence and Risk Factors Associated with Feline Infectious Peritonitis (FIP) in Mainland China between 2008 and 2023: A Systematic Review and Meta-Analysis

To evaluate the overall prevalence of FIP infection in cats in mainland China and associated risk factors, studies on the prevalence of FIP conducted from 1 January 2008 to 20 December 2023 were retrieved from five databases-CNKI, Wanfang, PubMed, Web of Science, and ScienceDirect-and comprehensively reviewed. The 21 studies selected, with a total of 181,014 samples, underwent a rigorous meta-analysis after quality assessment. The results revealed a 2% prevalence of FIP (95% CI: 1-2%) through the random-effects model, showing considerable heterogeneity (I2 = 95.2%). The subsequent subgroup analysis revealed that the age and gender of cats are significant risk factors for FIP infection in mainland China. In order to effectively reduce and control the prevalence of FIP on the Chinese mainland, we suggest improving the immunity of cats, with special attention given to health management in kittens and intact cats, and continuously monitoring FIPV.

Prevalence of natural feline coronavirus infection in domestic cats in Fujian, China

Only few studies have investigated the prevalence of feline coronavirus (FCoV) infection in domestic cats in Fujian, China. This is the first study to report the prevalence rate of FCoV infection in domestic cats in Fujian, China, and to analyse the epidemiological characteristics of FCoV infection in the region. A total of 112 cat faecal samples were collected from animal hospitals and catteries in the Fujian Province. RNA was extracted from faecal material for reverse transcription polymerase chain reaction (RT-PCR). The prevalence rate of FCoV infection was determined, and its epidemiological risk factors were analysed. The overall prevalence of FCoV infection in the cats, was 67.9%. We did not observe a significant association between the age, sex, or breed of the cats included in the study and the prevalence rate of the viral infection. Phylogenetic analysis showed that the four strains from Fujian were all type I FCoV. This is the first study to analyse the prevalence and epidemiological characteristics of FCoV infection in domestic cats in Fujian, China, using faecal samples. The results of this study provide preliminary data regarding the prevalence of FCoV infection in the Fujian Province for epidemiological studies on FCoV in China and worldwide. Future studies should perform systematic and comprehensive epidemiological investigations to determine the prevalence of FCoV infection in the region.

Immunoinformatics-aided rational design of a multi-epitope vaccine targeting feline infectious peritonitis virus

Feline infectious peritonitis (FIP) is a grave and frequently lethal ailment instigated by feline coronavirus (FCoV) in wild and domestic feline species. The spike (S) protein of FCoV assumes a critical function in viral ingress and infection, thereby presenting a promising avenue for the development of a vaccine. In this investigation, an immunoinformatics approach was employed to ascertain immunogenic epitopes within the S-protein of FIP and formulate an innovative vaccine candidate. By subjecting the amino acid sequence of the FIP S-protein to computational scrutiny, MHC-I binding T-cell epitopes were predicted, which were subsequently evaluated for their antigenicity, toxicity, and allergenicity through in silico tools. Our analyses yielded the identification of 11 potential epitopes capable of provoking a robust immune response against FIPV. Additionally, molecular docking analysis demonstrated the ability of these epitopes to bind with feline MHC class I molecules. Through the utilization of suitable linkers, these epitopes, along with adjuvants, were integrated to design a multi-epitope vaccine candidate. Furthermore, the stability of the interaction between the vaccine candidate and feline Toll-like receptor 4 (TLR4) was established via molecular docking and molecular dynamics simulation analyses. This suggests good prospects for future experimental validation to ascertain the efficacy of our vaccine candidate in inducing a protective immune response against FIP.

Feline Infectious Peritonitis: European Advisory Board on Cat Diseases Guidelines

Feline coronavirus (FCoV) is a ubiquitous RNA virus of cats, which is transmitted faeco-orally. In these guidelines, the European Advisory Board on Cat Diseases (ABCD) presents a comprehensive review of feline infectious peritonitis (FIP). FCoV is primarily an enteric virus and most infections do not cause clinical signs, or result in only enteritis, but a small proportion of FCoV-infected cats develop FIP. The pathology in FIP comprises a perivascular phlebitis that can affect any organ. Cats under two years old are most frequently affected by FIP. Most cats present with fever, anorexia, and weight loss; many have effusions, and some have ocular and/or neurological signs. Making a diagnosis is complex and ABCD FIP Diagnostic Approach Tools are available to aid veterinarians. Sampling an effusion, when present, for cytology, biochemistry, and FCoV RNA or FCoV antigen detection is very useful diagnostically. In the absence of an effusion, fine-needle aspirates from affected organs for cytology and FCoV RNA or FCoV antigen detection are helpful. Definitive diagnosis usually requires histopathology with FCoV antigen detection. Antiviral treatments now enable recovery in many cases from this previously fatal disease; nucleoside analogues (e.g., oral GS-441524) are very effective, although they are not available in all countries.

Serological Survey of Retrovirus and Coronavirus Infections, including SARS-CoV-2, in Rural Stray Cats in The Netherlands, 2020-2022

Stray cats can host (zoonotic) viral pathogens and act as a source of infection for domestic cats or humans. In this cross-sectional (sero)prevalence study, sera from 580 stray cats living in 56 different cat groups in rural areas in The Netherlands were collected from October 2020 to July 2022. These were used to investigate the prevalence of the cat-specific feline leukemia virus (FeLV, n = 580), the seroprevalence of the cat-specific feline viruses feline immunodeficiency virus (FIV, n = 580) and feline coronavirus (FCoV, n = 407), and the zoonotic virus severe acute respiratory coronavirus-2 (SARS-CoV-2, n = 407) using enzyme-linked immunosorbent assays (ELISAs). ELISA-positive results were confirmed using Western blot (FIV) or pseudovirus neutralization test (SARS-CoV-2). The FIV seroprevalence was 5.0% (95% CI (Confidence Interval) 3.4-7.1) and ranged from 0-19.0% among groups. FIV-specific antibodies were more often detected in male cats, cats ≥ 3 years and cats with reported health problems. No FeLV-positive cats were found (95% CI 0.0-0.6). The FCoV seroprevalence was 33.7% (95% CI 29.1-38.5) and ranged from 4.7-85.7% among groups. FCoV-specific antibodies were more often detected in cats ≥ 3 years, cats with reported health problems and cats living in industrial areas or countryside residences compared to cats living at holiday parks or campsites. SARS-CoV-2 antibodies against the subunit 1 (S1) and receptor binding domain (RBD) protein were detected in 2.7% (95% CI 1.4-4.8) of stray cats, but sera were negative in the pseudovirus neutralization test and therefore were considered SARS-CoV-2 suspected. Our findings suggest that rural stray cats in The Netherlands can be a source of FIV and FCoV, indicating a potential risk for transmission to other cats, while the risk for FeLV is low. However, suspected SARS-CoV-2 infections in these cats were uncommon. We found no evidence of SARS-CoV-2 cat-to-cat spread in the studied stray cat groups and consider the likelihood of spillover to humans as low.

Patterns of Feline Coronavirus Shedding and Associated Factors in Cats from Breeding Catteries

(1) Background: In households in which feline coronavirus (FCoV) is present, three patterns of FCoV shedding are described: non-shedders, intermittent (low-intensity) shedders, or persistent (high-intensity) shedders. It was the aim of this study to describe FCoV shedding patterns in cats from catteries in which FCoV infection is endemic. Additionally, risk factors for high-intensity FCoV shedding or non-shedding were analyzed. (2) Methods: Four fecal samples of 222 purebred cats from 37 breeding catteries were examined for FCoV RNA by quantitative reverse transcription polymerase chain reaction (RT-qPCR). High-intensity shedders were defined as cats positive for FCoV RNA in at least 3/4 fecal samples; non-shedding cats were defined as cats negative in all four fecal samples. Risk factor analysis was performed using information obtained by questionnaire. (3) Results: Of the 222 cats, 125 (56.3%) were considered high-intensity shedders, while 54/222 cats (24.3%) were FCoV non-shedders. The Persian breed was associated with a higher risk of high-intensity shedding in multivariable analysis, while Birman and Norwegian Forest Cats were more likely to be FCoV non-shedders. Cats living together with other cats were more likely to be FCoV shedders. (4) Conclusions: The proportion of both high-intensity shedders and non-shedding cats was higher than previously reported, which possibly can be explained by housing conditions, different genetic susceptibility, or differences in the study period. The risk of high-intensity shedding is higher in certain breeds. However, it cannot be excluded that the individual hygiene procedure of each breeder influenced FCoV-shedding frequency. A smaller group size is a protective factor against FCoV shedding.

Exploring the Enteric Virome of Cats with Acute Gastroenteritis

Viruses are a major cause of acute gastroenteritis (AGE) in cats, chiefly in younger animals. Enteric specimens collected from 29 cats with acute enteritis and 33 non-diarrhoeic cats were screened in PCRs and reverse transcription (RT) PCR for a large panel of enteric viruses, including also orphan viruses of recent identification. At least one viral species, including feline panleukopenia virus (FPV), feline enteric coronavirus (FCoV), feline chaphamaparvovirus, calicivirus (vesivirus and novovirus), feline kobuvirus, feline sakobuvirus A and Lyon IARC polyomaviruses, was detected in 66.1% of the samples.. Co-infections were mainly accounted for by FPV and FCoV and were detected in 24.2% of the samples. The virome composition was further assessed in eight diarrhoeic samples, through the construction of sequencing libraries using a sequence-independent single-primer amplification (SISPA) protocol. The libraries were sequenced on Oxford Nanopore Technologies sequencing platform. A total of 41 contigs (>100 nt) were detected from seven viral families infecting mammals, included Parvoviridae, Caliciviridae, Picornaviridae, Polyomaviridae, Anelloviridae, Papillomaviridae and Paramyxoviridae, revealing a broad variety in the composition of the feline enteric virome.

Coronaviruses: Troubling Crown of the Animal Kingdom

The existence of coronaviruses has been known for many years. These viruses cause significant disease that primarily seems to affect agricultural species. Human coronavirus disease due to the 2002 outbreak of Severe Acute Respiratory Syndrome and the 2012 outbreak of Middle East Respiratory Syndrome made headlines; however, these outbreaks were controlled, and public concern quickly faded. This complacency ended in late 2019 when alarms were raised about a mysterious virus responsible for numerous illnesses and deaths in China. As we now know, this novel disease called Coronavirus Disease 2019 (COVID-19) was caused by Severe acute respiratory syndrome-related-coronavirus-2 (SARS-CoV-2) and rapidly became a worldwide pandemic. Luckily, decades of research into animal coronaviruses hastened our understanding of the genetics, structure, transmission, and pathogenesis of these viruses. Coronaviruses infect a wide range of wild and domestic animals, with significant economic impact in several agricultural species. Their large genome, low dependency on host cellular proteins, and frequent recombination allow coronaviruses to successfully cross species barriers and adapt to different hosts including humans. The study of the animal diseases provides an understanding of the virus biology and pathogenesis and has assisted in the rapid development of the SARS-CoV-2 vaccines. Here, we briefly review the classification, origin, etiology, transmission mechanisms, pathogenesis, clinical signs, diagnosis, treatment, and prevention strategies, including available vaccines, for coronaviruses that affect domestic, farm, laboratory, and wild animal species. We also briefly describe the coronaviruses that affect humans. Expanding our knowledge of this complex group of viruses will better prepare us to design strategies to prevent and/or minimize the impact of future coronavirus outbreaks.

A Retrospective Study of Viral Molecular Prevalences in Cats in Southern Italy (Campania Region)

From 2019 to 2021, a retrospective molecular study was conducted in the Campania region (southern Italy) to determine the prevalence of viral diseases in domestic cats. A total of 328 dead animals were analyzed by Real-Time PCR for the presence of feline panleukopenia virus (FPV), feline leukemia virus (FeLV), feline enteric coronavirus (FCoV), rotavirus (RVA), feline herpesvirus type 1 (FHV-1), and feline calicivirus (FCV). The possible presence of SARS-CoV-2 was also investigated by Real-Time PCR. The cats included in this study were specifically sourced and referred by local veterinarians and local authorities to the Zooprofilactic Experimental Institute of Southern Italy (IZSM) for pathological evaluation. The samples consisted of owners, catteries, and stray cats. Results revealed: 73.5% positive cats for FPV (189/257), 23.6% for FeLV (21/89), 21.5% for FCoV (56/266), 11.4% for RVA (16/140), 9.05% for FeHV-1 (21/232), and 7.04 for FCV (15/213). In contrast, SARS-CoV-2 was never detected. FPV was more prevalent in winter (p = 0.0027). FCoV FHV-1, FCV, and RVA predominated in autumn, whereas FeLV predominated in summer. As expected, viral infections were found more frequently in outdoor and shelter cats than in indoor ones, although no statistical association was found between animal lifestyle and viral presence. The study showed a high prevalence of FPV, FeLV, and FCoV and a moderate prevalence of RVA, FHV-1, and FCV. Moreover, the prevalence of these pathogens varied among the cat populations investigated.

2022 AAFP/EveryCat Feline Infectious Peritonitis Diagnosis Guidelines

CLINICAL IMPORTANCE

Feline infectious peritonitis (FIP) is one of the most important infectious diseases and causes of death in cats; young cats less than 2 years of age are especially vulnerable. FIP is caused by a feline coronavirus (FCoV). It has been estimated that around 0.3% to 1.4% of feline deaths at veterinary institutions are caused by FIP.

SCOPE

This document has been developed by a Task Force of experts in feline clinical medicine as the 2022 AAFP/EveryCat Feline Infectious Peritonitis Diagnosis Guidelines to provide veterinarians with essential information to aid their ability to recognize cats presenting with FIP.

TESTING AND INTERPRETATION

Nearly every small animal veterinary practitioner will see cases. FIP can be challenging to diagnose owing to the lack of pathognomonic clinical signs or laboratory changes, especially when no effusion is present. A good understanding of each diagnostic test's sensitivity, specificity, predictive value, likelihood ratio and diagnostic accuracy is important when building a case for FIP. Before proceeding with any diagnostic test or commercial laboratory profile, the clinician should be able to answer the questions of 'why this test?' and 'what do the results mean?' Ultimately, the approach to diagnosing FIP must be tailored to the specific presentation of the individual cat.

RELEVANCE

Given that the disease is fatal when untreated, the ability to obtain a correct diagnosis is critical. The clinician must consider the individual patient's history, signalment and comprehensive physical examination findings when selecting diagnostic tests and sample types in order to build the index of suspicion 'brick by brick'. Research has demonstrated efficacy of new antivirals in FIP treatment, but these products are not legally available in many countries at this time. The Task Force encourages veterinarians to review the literature and stay informed on clinical trials and new drug approvals.

Reproductive Management in Catteries: Optimising health and wellbeing through veterinarian-breeder collaboration

PRACTICAL RELEVANCE

Many veterinarians - even those engaged in small animal reproduction - are uncomfortable with taking care of cat breeders or being in charge of catteries. Likely reasons for this are that feline reproduction is largely under-represented in undergraduate and graduate reproduction teaching, as well as in postgraduate education and science, whereas cat breeders themselves are often well informed and actively share knowledge with other cat breeders via the internet and social media.

CLINICAL CHALLENGES

A variety of problems can exist within a cattery, and collaboration between veterinarian and breeder to solve these is ultimately beneficial for the breeder, for the veterinarian, and for the health and wellbeing of the individual cats and of the cattery as a whole.

AIM

This review presents a comprehensive overview of aspects of cattery management that might negatively impact reproduction, including sanitation, hygiene and infectious disease control. It also discusses monitoring of reproductive performance, breeding recommendations, and the diagnostic and therapeutic approach to some common and specific problems.

EQUIPMENT AND TECHNICAL SKILLS

Reproductive management in the cattery requires no specialised equipment, as such. What it does need is an open mind, in terms of seeing how things are done, an open ear, for listening to the breeder, and the veterinarian's clinical skills in palpation, auscultation and, where required, further examination of the animals. Keeping abreast of the latest information on infectious diseases, disinfection and genetics ensures proper advice is provided.

EVIDENCE BASE

Current knowledge of reproductive management in catteries is summarised in order to apply an evidence-based approach, whenever possible. Notwithstanding, much of the information remains empirical.

Prevalence of anti-severe acute respiratory syndrome coronavirus 2 antibodies in cats in Germany and other European countries in the early phase of the coronavirus disease-19 pandemic

During the first months of the coronavirus disease (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), cases of human-to-cat transmission were reported. Seroconversion was shown in cats infected under experimental and natural conditions. This large-scale survey of 1,005 serum samples was conducted to investigate anti-SARS-CoV-2 antibody prevalence in domestic cats during the first 7 months of the pandemic in Germany and other European countries. In addition, we compared the sensitivity and specificity of two multispecies SARS-CoV-2 antibody enzyme-linked immunosorbent assays (ELISA). Results were confirmed by using an indirect immunofluorescence test (iIFT) and a surrogate virus neutralization test (sVNT). Sera that were highly positive for feline coronavirus (FCoV) antibodies (n = 103) were included to correct for cross-reactivity of the tests used. Our results showed an overall SARS-CoV-2 seropositivity of 1.9% (n = 19) in a receptor-binding domain (RBD)-based ELISA, additional 0.8% (n = 8) were giving inconclusive results. In contrast, a nucleocapsid-based ELISA revealed 0.5% (n = 5) positive and 0.2% (n = 2) inconclusive results. While the iIFT and sVNT confirmed 100% of positive and 50%-57.1% of the doubtful results as determined in the RBD ELISA, the nucleocapsid-based assay showed a high discrepancy and only one of the five positive results could be confirmed. The results indicate significant deficits of the nucleocapsid-based ELISA with respect to sensitivity and specificity. Due to a significantly higher rate (5.8%) of positive results in the group of highly FCoV antibody-positive samples, cross-reactivity of the FCoV-ELISA with SARS-CoV-2 antibodies cannot be excluded. Furthermore, we investigated the impact of direct contact of domestic cats (n = 23) to SARS-CoV-2 positive owners. Considering one inconclusive result, which got confirmed by iIFT, this exposure did not lead to a significantly higher prevalence (4.4%; p = .358) among tested subjects. Overall, we conclude that cats are a negligible entity with respect to virus transmission in Europe.

Fecal Feline Coronavirus RNA Shedding and Spike Gene Mutations in Cats with Feline Infectious Peritonitis Treated with GS-441524

As previously demonstrated by our research group, the oral multicomponent drug Xraphconn® containing GS-441524 was effective at curing otherwise fatal feline infectious peritonitis (FIP) in 18 feline coronavirus (FCoV)-infected cats. The aims of the current study were to investigate, using samples from the same animals as in the previous study, (1) the effect of treatment on fecal viral RNA shedding; (2) the presence of spike gene mutations in different body compartments of these cats; and (3) viral RNA shedding, presence of spike gene mutations, and anti-FCoV antibody titers in samples of 12 companion cats cohabitating with the treated cats. Eleven of the eighteen treated FIP cats (61%) were shedding FCoV RNA in feces within the first three days after treatment initiation, but all of them tested negative by day 6. In one of these cats, fecal shedding reoccurred on day 83. Two cats initially negative in feces were transiently positive 1-4 weeks into the study. The remaining five cats never shed FCoV. Viral RNA loads in feces decreased with time comparable with those in blood and effusion. Specific spike gene mutations linked to systemic FCoV spread were consistently found in blood and effusion from treated FIP cats, but not in feces from treated or companion cats. A new mutation that led to a not yet described amino acid change was identified, indicating that further mutations may be involved in the development of FIP. Eight of the twelve companion cats shed FCoV in feces. All but one of the twelve companion cats had anti-FCoV antibodies. Oral treatment with GS-441524 effectively decreased viral RNA loads in feces, blood, and effusion in cats with FIP. Nonetheless, re-shedding can most likely occur if cats are re-exposed to FCoV by their companion cats.

Role of Feline Coronavirus as Contributor to Diarrhea in Cats from Breeding Catteries

(1) Background: Feline coronavirus infection (FCoV) is common in multi-cat environments. A role of FCoV in causing diarrhea is often assumed, but has not been proven. The aim of this study was to evaluate an association of FCoV infection with diarrhea in multi-cat environments. (2) Methods: The study included 234 cats from 37 catteries. Fecal samples were analyzed for FCoV RNA by reverse transcriptase quantitative polymerase chain reaction (RT-qPCR). Potential co-infections were determined by applying a qPCR panel on different potential enteropathogens and fecal flotation. A fecal scoring system was used to categorize feces as diarrheic or non-diarrheic. (3) Results: Of the 234 cats included, 23 had diarrhea. The prevalence of FCoV infection was 87.0% in cats with and 58.8% in cats without diarrhea. FCoV infection was significantly associated with diarrhea (Odds Ratio (OR) 5.01; p = 0.008). In addition, presence of Clostridium perfringens α toxin (OR 6.93; p = 0.032) and feline panleukopenia virus (OR 13.74; p = 0.004) were associated with an increased risk of diarrhea. There was no correlation between FCoV load and fecal score. FCoV-positive cats with co-infections were not more likely to have diarrhea than FCoV-positive cats without co-infections (p = 0.455). (4) Conclusions: FCoV infection is common in cats from catteries and can be associated with diarrhea.

Epidemiology and Comparative Analyses of the S Gene on Feline Coronavirus in Central China

Feline coronavirus (FCoV) infections present as one of two forms: a mild or symptom-less enteric infection (FEC) and a fatal systemic disease termed feline infectious peritonitis (FIP). The lack of epidemiology of FCoV in central China and the reason why different symptoms are caused by viruses of the same serotype have motivated this investigation. Clinical data of 81 suspected FIP cases, 116 diarrhea cases and 174 healthy cases were collected from veterinary hospitals using body cavity effusion or fecal samples. Risk factors, sequence comparison and phylogenetic studies were performed. The results indicated that FIPV was distinguished from FECV in the average hydrophobicity of amino acids among the cleavage sites of furin, as well as the mutation sites 23,531 and 23,537. FIPV included a higher minimal R-X-X-R recognition motif of furin (41.94%) than did FECV (9.1%). The serotype of FCoV was insignificantly correlated with FIP, and the clade 1 and clade 2 strains that appeared were unique to central China. Thus, it is hypothesized that this, along with the latent variables of an antigenic epitope at positions 1058 and 1060, as well as mutations at the S1/S2 sites, are important factors affecting FCoV transmission and pathogenicity.

Direct Detection of Feline Coronavirus by Three Rapid Antigen Immunochromatographic Tests and by Real-Time PCR in Cat Shelters

The aim of this study was the direct detection of feline coronavirus by real-time PCR and by three different rapid immunochromatographic (RIM) tests detecting antigens in faecal samples of shelter cats. Based on sensitivity and specificity calculated for each of the RIM tests, the utility of RIM tests was compared. Seventy faecal samples originating from shelter cats housed in quarantine were examined. Out of 70 samples analyzed by real-time PCR, 44 (62.9%) were positive. Significantly more cats (p < 0.05) tested positive than negative. Neither age nor sex of the cats played a significant role (p > 0.05) in the shedding status of the virus. The sensitivity of the RIM tests was found to be at low (<35%; RIM tests A and C) to satisfactory level (>50%, RIM test B). The number of virus particles determined by real-time RT-PCR analysis did not significantly correlate with the results detected by any of the RIM tests (p > 0.05). The results of this study indicate that the use of rapid antigen RIM tests in routine screening of FCoV shedding status in shelter cats is limited due to the occurrence of a high number of false negative results.

One Health: EAACI Position Paper on coronaviruses at the human-animal interface, with a specific focus on comparative and zoonotic aspects of SARS-CoV-2

The latest outbreak of a coronavirus disease in 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), evolved into a worldwide pandemic with massive effects on health, quality of life, and economy. Given the short period of time since the outbreak, there are several knowledge gaps on the comparative and zoonotic aspects of this new virus. Within the One Health concept, the current EAACI position paper dwells into the current knowledge on SARS-CoV-2's receptors, symptoms, transmission routes for human and animals living in close vicinity to each other, usefulness of animal models to study this disease and management options to avoid intra- and interspecies transmission. Similar pandemics might appear unexpectedly and more frequently in the near future due to climate change, consumption of exotic foods and drinks, globe-trotter travel possibilities, the growing world population, the decreasing production space, declining room for wildlife and free-ranging animals, and the changed lifestyle including living very close to animals. Therefore, both the society and the health authorities need to be aware and well prepared for similar future situations, and research needs to focus on prevention and fast development of treatment options (medications, vaccines).

Molecular Detection of Feline Coronavirus Based on Recombinase Polymerase Amplification Assay

Feline coronavirus (FCoV) is endemic in cat populations worldwide. Persistently, subclinically infected cats play a significant role in spreading the infection. Testing fecal samples of cats may facilitate efforts to decrease the viral burden within a population. Real-time RT-PCR is highly sensitive and specific for the detection of FCoV but must be performed in a fully equipped laboratory. A simple and accurate assay is needed to identify FCoV at the point-of-need. The aim of this study was to develop a rapid FCoV detection assay based on isothermal amplification technology, i.e., reverse transcription-recombinase polymerase amplification (RT-RPA). Primers were designed to target the highly conserved 3′ untranslated region of the 7b gene. Running on a constant temperature of 42 °C, reverse transcription as well as DNA amplification and detection was achieved in a maximum of 15 min. A probit analysis revealed a detection limit of 58.5 RNA copies/reaction. For cross-detection, nucleic acids from 19 viruses were tested. Both RT-RPA and real-time RT-PCR showed cross-detection with canine coronavirus and transmissible gastroenteritis virus, but not with other pathogens. To evaluate clinical performance, RNA was extracted from 39 fecal samples from cats. All samples were tested simultaneously with real-time RT-PCR resulting in a RT-RPA sensitivity and specificity of 90.9% and 100%, respectively. RT-RPA can be considered a promising simple method for rapid detection of FCoV.

Prevalence and molecular characteristics of feline coronavirus in southwest China from 2017 to 2020

Feline coronavirus (FCoV) is the causative agent of feline infectious peritonitis and diarrhoea in kittens worldwide. In this study, a total of 173 feline diarrhoeal faecal and ascetic samples were collected from 15 catteries and six veterinary hospitals in southwest China from 2017 to 2020. FCoV was detected in 80.35 % (139/173) of the samples using the RT-nPCR method; these included infections with 122 type I FCoV and 57 type II FCoV. Interestingly, 51 cases had co-infection with types I and II, the first such report in mainland China. To further analyse the genetic diversity of FCoV, we amplified 23 full-length spike (S) genes, including 18 type I and five type II FCoV. The type I FCoV and type II FCoV strains shared 85.5-98.7% and 97.4-98.9% nucleotide (nt) sequence identities between one another, respectively. The N-terminal domain (NTD) of 23 FCoV strains showed a high degree of variation (73.6-80.3 %). There was six type I FCoV strains with two amino acid insertions (159HL160) in the NTD. In addition, 18 strains of type I FCoV belonged to the Ie cluster, and five strains of type II FCoV were in the IIb cluster based on phylogenetic analysis. Notably, it was first time that two type I FCoV strains had recombination in the NTD, and the recombination regions was located 140-857 nt of the S gene. This study constitutes a systematic investigation of the current infection status and molecular characteristics of FCoV in southwest China.

Seroprevalence of Infection with Feline Morbilliviruses Is Associated with FLUTD and Increased Blood Creatinine Concentrations in Domestic Cats

Feline morbilliviruses (FeMV) are fairly newly discovered paramyxoviruses found in cats. The first description indicated an association with widely distributed chronic kidney disease (CKD) in the host species. In various studies, a global prevalence and a further genotype, designated FeMV-2, and the involvement of other organ systems in infected individuals were shown. Using an immunofluorescence assay, we detected an overall seroprevalence of FeMV in almost half of the cats investigated (n = 380), with a significantly increased proportion in younger animals. In comparison to European Shorthair cats, the rate of seropositivity is higher in pedigree cats. Regardless of the breed, FeMV infection was associated with increased blood creatinine concentrations, suggesting an association with CKD. Further analysis indicated that this association was the strongest in animals having high IFA titers against FeMV-2. In addition, a significant association between FeMV-positive status and the prevalence of feline lower urinary tract disease (FLUTD, or idiopathic cystitis) was detected. This association was dominated by cats having antibodies against FeMV-1 only. To further evaluate the positive correlation between FeMV seroprevalence and CKD as well as FLUTD, consideration of additional clinical characteristics and laboratory parameters is warranted, and controlled infection studies with both FeMV genotypes are necessary. Clinicians should, however, be aware of a possible link between renal and lower urinary tract disease and FeMV infections.

Understanding the outcomes of COVID-19 - does the current model of an acute respiratory infection really fit?

Although coronavirus disease 2019 (COVID-19) is regarded as an acute, resolving infection followed by the development of protective immunity, recent systematic literature review documents evidence for often highly prolonged shedding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in respiratory and faecal samples, periodic recurrence of PCR positivity in a substantial proportion of individuals and increasingly documented instances of reinfection associated with a lack of protective immunity. This pattern of infection is quite distinct from the acute/resolving nature of other human pathogenic respiratory viruses, such as influenza A virus and respiratory syncytial virus. Prolonged shedding of SARS-CoV-2 furthermore occurs irrespective of disease severity or development of virus-neutralizing antibodies. SARS-CoV-2 possesses an intensely structured RNA genome, an attribute shared with other human and veterinary coronaviruses and with other mammalian RNA viruses such as hepatitis C virus. These are capable of long-term persistence, possibly through poorly understood RNA structure-mediated effects on innate and adaptive host immune responses. The assumption that resolution of COVID-19 and the appearance of anti-SARS-CoV-2 IgG antibodies represents virus clearance and protection from reinfection, implicit for example in the susceptible-infected-recovered (SIR) model used for epidemic prediction, should be rigorously re-evaluated.

Diagnostic Value of Detecting Feline Coronavirus RNA and Spike Gene Mutations in Cerebrospinal Fluid to Confirm Feline Infectious Peritonitis

BACKGROUND

Cats with neurologic feline infectious peritonitis (FIP) are difficult to diagnose. Aim of this study was to evaluate the diagnostic value of detecting feline coronavirus (FCoV) RNA and spike (S) gene mutations in cerebrospinal fluid (CSF).

METHODS

The study included 30 cats with confirmed FIP (six with neurological signs) and 29 control cats (eleven with neurological signs) with other diseases resulting in similar clinical signs. CSF was tested for FCoV RNA by 7b-RT-qPCR in all cats. In RT-qPCR-positive cases, S-RT-qPCR was additionally performed to identify spike gene mutations.

RESULTS

Nine cats with FIP (9/30, 30%), but none of the control cats were positive for FCoV RNA in CSF. Sensitivity of 7b-RT-qPCR in CSF was higher for cats with neurological FIP (83.3%; 95% confidence interval (95% CI) 41.8-98.9) than for cats with non-neurological FIP (16.7%; 95% CI 6.1-36.5). Spike gene mutations were rarely detected.

CONCLUSIONS

FCoV RNA was frequently present in CSF of cats with neurological FIP, but only rarely in cats with non-neurological FIP. Screening for spike gene mutations did not enhance specificity in this patient group. Larger populations of cats with neurological FIP should be explored in future studies.

Occurrence of Antibodies against SARS-CoV-2 in the Domestic Cat Population of Germany

Domestic cats (Felis catus) are popular companion animals that live in close contact with their human owners. Therefore, the risk of a trans-species spreading event between domestic cats and humans is ever-present. Shortly after the emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its rapid spread around the world, the role of domestic cats in the transmission cycle was questioned. In the present study, the first large-scale survey of antibody occurrence in the domestic cat population in Germany was conducted, in order to assess the incidence of naturally occurring human to cat transmission of SARS-CoV-2. A total of 920 serum samples, which were collected from April to September of 2020, were screened by an indirect multispecies ELISA. Positive samples were verified using an indirect immunofluorescence test (iIFT) and additionally tested for neutralizing antibodies. Furthermore, serum samples were screened for antibodies against feline coronavirus (FCoV), in order to rule out cross-reactivity in the described test systems. Overall, 0.69% (6/920) of serum samples were found to be positive for antibodies against SARS-CoV-2 by ELISA and iIFT. Two of these reactive sera also displayed neutralizing antibodies. No cross-reactivity with FCoV-specific antibodies was observed. The finding of SARS-CoV-2 antibody-positive serum samples in the domestic cat population of Germany, during a period when the incidence of human infection in the country was still rather low, indicates that human-to-cat transmission of SARS-CoV-2 happens, but there is no indication of SARS-CoV-2 circulation in cats.

Identification of Novel Astroviruses in the Gastrointestinal Tract of Domestic Cats

Astroviruses, isolated from numerous avian and mammalian species including humans, are commonly associated with enteritis and encephalitis. Two astroviruses have previously been identified in cats, and while definitive evidence is lacking, an association with enteritis is suggested. Using metagenomic next-generation sequencing of viral nucleic acids from faecal samples, we identified two novel feline astroviruses termed Feline astrovirus 3 and 4. These viruses were isolated from healthy shelter-housed kittens (Feline astrovirus 3; 6448 bp) and from a kitten with diarrhoea that was co-infected with Feline parvovirus (Feline astrovirus 4, 6549 bp). Both novel astroviruses shared a genome arrangement of three open reading frames (ORFs) comparable to that of other astroviruses. Phylogenetic analysis of the concatenated ORFs, ORF1a, ORF1b and capsid protein revealed that both viruses were phylogenetically distinct from other feline astroviruses, although their precise evolutionary history could not be accurately determined due to a lack of resolution at key nodes. Large-scale molecular surveillance studies of healthy and diseased cats are needed to determine the pathogenicity of feline astroviruses as single virus infections or in co-infections with other enteric viruses.