Chronic Infection of Domestic Cats with Feline Morbillivirus, United States

Detection of Antibodies against Feline Morbillivirus by Recombinant Matrix Enzyme-Linked Immunosorbent Assay

Feline morbillivirus (FeMV) has been associated with feline health, although its exact role in pathogenesis is still debated. In this study, an indirect enzyme-linked immunosorbent assay (i-ELISA) targeting a recombinant matrix protein of FeMV (rFeMV-M) was developed and assessed in comparison to a Western blotting (WB) assay. The i-ELISA was evaluated using blood samples from 136 cats that were additionally tested with real-time reverse-transcription PCR (RT-qPCR). The i-ELISA exhibited a sensitivity of 90.1%, specificity of 75.6%, positive predictive value of 88.2%, and negative predictive value of 79.1%. The agreement between i-ELISA and WB analyses was substantial (a κ coefficient of 0.664 with a 95% confidence interval of 0.529 to 0.799). Within the study group, 68.4% (93/136) of the cats were serologically positive in the i-ELISA and 66.9% (91/136) in the WB assay, with 11.8% (11/93) of false positivity with the i-ELISA. However, only 8.1% (11/136) of the cats tested positive for FeMV using RT-qPCR (p < 0.001). The developed i-ELISA proved effective in identifying FeMV-infected cats and indicated the prevalence of FeMV exposure. Combining FeMV antibody detection through i-ELISA with FeMV RT-qPCR could offer a comprehensive method to determine and monitor FeMV infection status. Nevertheless, this assay still requires refinement due to a significant number of false positive results, which can lead to the misdiagnosis of cats without antibodies as having antibodies. This study also provided the first evidence of seroprevalence against FeMV among cat populations in Thailand, contributing valuable insights into the geographic distribution and prevalence of this virus.

Detection of feline morbillivirus in cats with symptoms of acute febrile infection

Feline morbillivirus (FeMV) was identified for the first time in cats in 2012 in Hong Kong. Although its association with chronic kidney disease in cats has attracted the attention of researchers, its clinical significance as an acute infection has not been reported. Previously, we reported FeMV detection using next-generation sequence-based comprehensive genomic analysis of plasma samples from cats with suspected acute febrile infections. Here, we conducted an epidemiological survey to detect FeMV by quantitative reverse transcription polymerase chain reaction (qRT-PCR) using blood samples from cats in Japan. FeMV was detected in 32/102 blood samples (31.4%) from cats with suspected acute viral infections. Most of the FeMV-positive cats had clinical findings consistent with acute viral infections, including fever, leukopenia, thrombocytopenia and jaundice. No FeMV was detected in healthy cats or clinically ill cats that visited veterinary hospitals. Phylogenetic analysis classified FeMV L genes into various FeMV subtypes. We also necropsied a FeMV-positive cat that died of a suspected acute infection. On necropsy, FeMV was detected in systemic organs, including the kidneys, lymph nodes and spleen by qRT-PCR and immunohistochemical staining. These results suggest that FeMV infections may cause acute symptomatic febrile infections in cats. A limitation of this study was that the involvement of other pathogens that cause febrile illnesses could not be ruled out and this prevented a definitive conclusion that FeMV causes febrile disease in infected cats. Further studies that include experimental infections are warranted to determine the pathogenicity of FeMV in cats.

Persistent paramyxovirus infections: in co-infections the parainfluenza virus type 5 persistent phenotype is dominant over the lytic phenotype

Parainfluenza virus type 5 (PIV5) can either have a persistent or a lytic phenotype in cultured cells. We have previously shown that the phenotype is determined by the phosphorylation status of the phosphoprotein (P). Single amino acid substitutions at critical residues, including a serine-to-phenylalanine substitution at position 157 on P, result in a switch between persistent and lytic phenotypes. Here, using PIV5 vectors expressing either mCherry or GFP with persistent or lytic phenotypes, we show that in co-infections the persistent phenotype is dominant. Thus, in contrast to the cell death observed with cells infected solely with the lytic variant, in co-infected cells persistence is immediately established and both lytic and persistent genotypes persist. Furthermore, 10-20 % of virus released from dually infected cells contains both genotypes, indicating that PIV5 particles can package more than one genome. Co-infected cells continue to maintain both genotypes/phenotypes during cell passage, as do individual colonies of cells derived from a culture of persistently infected cells. A refinement of our model on how the dynamics of virus selection may occur in vivo is presented.

Paramyxoviruses: Pathogenesis, Vaccines, Antivirals, and Prototypes for Pandemic Preparedness

The Paramyxoviridae family includes established human pathogens such as measles virus, mumps virus, and the human parainfluenza viruses; highly lethal zoonotic pathogens such as Nipah virus; and a number of recently identified agents, such as Sosuga virus, which remain poorly understood. The high human-to-human transmission rate of paramyxoviruses such as measles virus, high case fatality rate associated with other family members such as Nipah virus, and the existence of poorly characterized zoonotic pathogens raise concern that known and unknown paramyxoviruses have significant pandemic potential. In this review, the general life cycle, taxonomic relationships, and viral pathogenesis are described for paramyxoviruses that cause both systemic and respiratory system-restricted infections. Next, key gaps in critical areas are presented, following detailed conversations with subject matter experts and based on the current literature. Finally, we present an assessment of potential prototype pathogen candidates that could be used as models to study this important virus family, including assessment of the strengths and weaknesses of each potential prototype.

Feline Morbillivirus: Clinical Relevance of a Widespread Endemic Viral Infection of Cats

Feline morbillivirus (FeMV) was first isolated in 2012 from stray cats in Hong Kong. It has been found in association with tubulointerstitial nephritis (TIN), the most common cause of feline chronic kidney disease (CKD). However, viral host spectrum and virus tropism go beyond the domestic cat and kidney tissues. The viral genetic diversity of FeMV is extensive, but it is not known if this is clinically relevant. Urine and kidney tissues have been widely tested in attempts to confirm associations between FeMV infection and renal disease, but samples from both healthy and sick cats can test positive and some cross-sectional studies have not found associations between FeMV infection and CKD. There is also evidence for acute kidney injury following infection with FeMV. The results of prevalence studies differ greatly depending on the population tested and methodologies used for detection, but worldwide distribution of FeMV has been shown. Experimental studies have confirmed previous field observations that higher viral loads are present in the urine compared to other tissues, and renal TIN lesions associated with FeMV antigen have been demonstrated, alongside virus lymphotropism and viraemia-associated lymphopenia. Longitudinal field studies have revealed persistent viral shedding in urine, although infection can be cleared spontaneously.

Genetic Diversity and Evolution of Viruses Infecting Felis catus: A Global Perspective

Cats harbor many important viral pathogens, and the knowledge of their diversity has been greatly expanded thanks to increasingly popular molecular sequencing techniques. While the diversity is mostly described in numerous regionally defined studies, there lacks a global overview of the diversity for the majority of cat viruses, and therefore our understanding of the evolution and epidemiology of these viruses was generally inadequate. In this study, we analyzed 12,377 genetic sequences from 25 cat virus species and conducted comprehensive phylodynamic analyses. It revealed, for the first time, the global diversity for all cat viruses known to date, taking into account highly virulent strains and vaccine strains. From there, we further characterized and compared the geographic expansion patterns, temporal dynamics and recombination frequencies of these viruses. While respiratory pathogens such as feline calicivirus showed some degree of geographical panmixes, the other viral species are more geographically defined. Furthermore, recombination rates were much higher in feline parvovirus, feline coronavirus, feline calicivirus and feline foamy virus than the other feline virus species. Collectively, our findings deepen the understanding of the evolutionary and epidemiological features of cat viruses, which in turn provide important insight into the prevention and control of cat pathogens.

Novel and classical morbilliviruses: Current knowledge of three divergent morbillivirus groups

Currently, seven species of morbillivirus have been classified. Six of these species (Measles morbillivirus, Rinderpest morbillivirus, Small ruminant morbillivirus, Canine morbillivirus, Phocine morbillivirus, and Cetacean morbillivirus) are highly infectious and cause serious systemic diseases in humans, livestock, domestic dogs, and wild animals. These species commonly use the host proteins signaling lymphocytic activation molecule (SLAM) and nectin-4 as receptors, and this usage contributes to their virulence. The seventh species (Feline morbillivirus: FeMV) is phylogenetically divergent from the six SLAM-using species. FeMV differs from the SLAM-using morbillivirus group in pathogenicity and infectivity, and is speculated to use non-SLAM receptors. Recently, novel species of morbilliviruses have been discovered in bats, rodents, and domestic pigs. Because the ability to use SLAM and nectin-4 is closely related to the infectivity and pathogenicity of morbilliviruses, investigation of the potential usage of these receptors is useful for estimating infectivity and pathogenicity. The SLAM-binding sites in the receptor-binding protein show high similarity among the SLAM-using morbilliviruses. This feature may help to estimate whether novel morbillivirus species can use SLAM as a receptor. A novel morbillivirus species isolated from wild mice diverged from the classified morbilliviruses in the phylogenetic tree, forming a third group separate from the SLAM-using morbillivirus group and FeMV. This suggests that the novel rodent morbillivirus may exhibit a different risk from the SLAM-using morbillivirus group, and analyses of its viral pathogenicity and infectivity toward humans are warranted.

FeMV is a cathepsin-dependent unique morbillivirus infecting the kidneys of domestic cats

Feline morbillivirus (FeMV) is a recently discovered pathogen of domestic cats and has been classified as a morbillivirus in the Paramyxovirus family. We determined the complete sequence of FeMV^US5 directly from an FeMV-positive urine sample without virus isolation or cell passage. Sequence analysis of the viral genome revealed potential divergence from characteristics of archetypal morbilliviruses. First, the virus lacks the canonical polybasic furin cleavage signal in the fusion (F) glycoprotein. Second, conserved amino acids in the hemagglutinin (H) glycoprotein used by all other morbilliviruses for binding and/or fusion activation with the cellular receptor CD150 (signaling lymphocyte activation molecule [SLAM]/F1) are absent. We show that, despite this sequence divergence, FeMV H glycoprotein uses feline CD150 as a receptor and cannot use human CD150. We demonstrate that the protease responsible for cleaving the FeMV F glycoprotein is a cathepsin, making FeMV a unique morbillivirus and more similar to the closely related zoonotic Nipah and Hendra viruses. We developed a reverse genetics system for FeMV^US5 and generated recombinant viruses expressing Venus fluorescent protein from an additional transcription unit located either between the phospho-protein (P) and matrix (M) genes or the H and large (L) genes of the genome. We used these recombinant FeMVs to establish a natural infection and demonstrate that FeMV causes an acute morbillivirus-like disease in the cat. Virus was shed in the urine and detectable in the kidneys at later time points. This opens the door for long-term studies to address the postulated role of this morbillivirus in the development of chronic kidney disease.

In Vitro Growth, Receptor Usage and Pathogenesis of Feline Morbillivirus in the Natural Host

Feline morbillivirus (FeMV) is a recently discovered virus belonging to the genus Morbillivirus of the virus family Paramyxoviridae. Often, the virus has been detected in urine of cats with a history of urinary disease and has a worldwide distribution. Currently, it is unclear which receptor the virus uses to enter the target cells. Furthermore, many aspects of FeMV biology in vivo, including tissue tropism, pathogenesis, and virus excretion in the natural host remain unclear. In this study we analyzed the replication of FeMV in various cell lines. Secondly, we tested if the presence of feline SLAMF1 (Signaling Lymphocytic Activation Molecule family 1/CD150, principal entry receptor for other members of the Morbillivirus genus) improved FeMV replication efficiency in vitro. Finally, to elucidate in vivo biology in cats, as a natural host for FeMV, we experimentally infected a group of cats and monitored clinical symptoms, viremia, and excretion of the virus during the course of 56 days. Our study showed that FeMV shares some features with other morbilliviruses like the use of the SLAMF1 receptor. For the first time, experimental infection of SPF cats showed that FeMV does not induce an acute clinical disease like other morbilliviruses but can induce lesions in the kidneys, including tubulointerstitial nephritis. Further investigations are needed to confirm the site and dynamics of replication of FeMV in the urinary tract and the longer-term impact of FeMV-induced lesions on the renal function. Whether FeMV infection can result in chronic kidney disease will require the monitoring of cats over a longer period.

Renal epitheliotropism of feline morbillivirus in two cats

The association of feline morbillivirus (FeMV) with kidney disease in cats is controversial. Two cats with a history of severe hematuria had eosinophilic inclusion-like bodies in the renal tubular epithelial cells, without any inflammatory cellular reaction. Ultrastructurally, aggregations of electron-dense viral-like particles were found where the inclusion-like bodies were located. Immunohistochemistry (IHC) using antibodies against FeMV matrix protein labeled these inclusion-like bodies, and also labeled the cytoplasm of tracheal and bronchiolar epithelial cells, and lymphocytes and macrophages in spleen and mesenteric lymph node. Using double IHC, FeMV antigen was detected in astroglia and oligodendroglia but not in microglia. Phylogenetic characterization of the fusion and hemagglutinin gene sequences revealed FeMV-1A genotypes in both cats. These findings indicated an active viral infection with FeMV. We propose that FeMV is a renal epitheliotropic virus and also localizes in various other tissues.

Feline morbillivirus-1 in dogs with respiratory diseases

Feline morbillivirus-1 (FeMV-1) is a viral pathogen associated with kidney disease in domestic cats and wild felids. We initially identified the FeMV-1 from the lung of a necropsied dog with severe pulmonary disease by the reverse transcription polymerase chain reaction (RT-PCR). Thereafter, we investigated FeMV-1 in nasal and oral swab samples from 73 healthy and 113 dogs with respiratory illnesses. We found polymerase chain reaction (PCR)-positive FeMV-1 from only 14/113 (12.39%) dogs with respiratory disease (p = .001). Of these 14 dogs, six were co-infected with other canine respiratory viruses (6/14; 42.86%). Two independent immunohistochemistry procedures, using antibodies against matrix and phosphoprotein of FeMV-1, confirmed the presence of FeMV-1 in lung tissues of two necropsied dogs (out of a total of 22 dogs, 9.09%) that died from respiratory disease. This finding corresponded to transmission electron microscopy findings that paramyxoviral particles exist in lung epithelia. FeMV-1 antigen localization was also evident in the kidney, lymphoid and brain tissues of two deceased dogs. FeMV-1 was successfully isolated from a necropsied dog and from two living dogs, all with respiratory illnesses, which supports FeMV infection in dogs. The detection of FeMV-1 in dog tissues expands the known tropism of this virus to a non-felid host. Our findings indicate that FeMV-1, alone or in co-infection with other viral pathogens, might contribute to respiratory illness and death in dogs.

Feline Morbillivirus in Southern Italy: Epidemiology, Clinico-Pathological Features and Phylogenetic Analysis in Cats

Feline morbillivirus (FeMV) was isolated for the first time in 2012 with an association with chronic kidney disease (CKD) suggested. This study aimed at investigating in cats from southern Italy FeMV prevalence and risk factors for exposure to FeMV, including the relationship with CKD; sequencing amplicons and analyzing phylogeny of PCR positive samples. Blood serum, K₃EDTA blood and urine samples from 223 cats were investigated. Ten carcasses were also evaluated. FeMV RNA was detected in 2.4% (5/211) blood and 16.1% (36/223) urine samples. One carcass tested positive by qPCR_FeMV from kidney, urinary bladder, and submandibular lymph nodes. Antibodies against FeMV were detected in 14.5% (28/193) cats. We followed up 27 cats (13 FeMV positive cats) and documented in some cases urine shedding after up to 360 days. Older and foundling cats and cats living in rescue catteries, were more frequently infected with FeMV. A significant correlation between FeMV and higher serum creatinine values or low urine specific gravity was found. FeMV positivity was significantly associated with retroviral infection, and the presence of some clinical signs apart from CKD clinicopathological markers. Our study highlights the possibility of a link between FeMV exposure and CKD and a general impairment of feline health.

Feline morbillivirus in northwestern Italy: first detection of genotype 1-B

OBJECTIVES

A novel morbillivirus was recently described in stray and domestic cats in Asia, the USA and Europe. Most cats infected with feline morbillivirus (FeMV) showed lower urinary tract or kidney disease. Although the association of FeMV infection and kidney diseases has been suggested, the virus pathogenicity remains unclear. The present study aimed to investigate the distribution of FeMV infection, as well as the relationship between FeMV infection and kidney diseases in cats from northwestern Italy.

METHODS

A total of 153 urine samples (150 individuals and three pools) and 50 kidney samples were collected and included in the study; total RNA was extracted and a reverse transcription quantitative PCR (RT-qPCR) was performed in order to identify FeMV. Kidneys were also submitted to anatomopathological examination. Phylogenetic analysis and isolation attempts were carried out on positive samples. In FeMV-positive cats, urinalysis and blood analysis were performed.

RESULTS

FeMV RNA was detected in 7.3% of urine samples and in 8% of kidney samples, both in healthy cats and in cats with clinical signs/post-mortem lesions compatible with kidney disease. At histopathological examination, tubulointerstitial nephritis (TIN) was shown in 3/4 positive kidney samples, but a clear relationship between FeMV and TIN was not observed. Isolation attempts were unsuccessful, although the urine sample of one castrated male cat hosted in a cattery showed a positive signal in RT-qPCR until the fourth cell passage. Phylogenetic analysis revealed that this FeMV strain belonged to genotype 1-B. In the same cattery, a second genotype 1-B variant was detected from a urine pool. Urinalysis showed proteinuria in three cats, while at blood analysis three cats presented altered creatinine levels.

CONCLUSIONS AND RELEVANCE

Data reported suggest the presence of a FeMV sub-cluster distinct from the strain previously isolated in Italy, whose role in renal disorders remains uncertain.

First detection of Feline morbillivirus infection in white-eared opossums (Didelphis albiventris, Lund, 1840), a non-feline host

Feline Morbillivirus (FeMV) was first detected in 2012 in domestic cats from Hong Kong and was found to be associated with tubulointerstitial nephritis and chronic kidney disease. In subsequent studies in other countries, FeMV was detected in asymptomatic cats. However, it is not clear whether FeMV plays a role as a pathogen in the kidney diseases of cats, and other epidemiological data are still unknown. To date, studies have reported the presence of FeMV exclusively in domestic cats. This study is the first molecular detection of the FeMV RNA associated with pathological and immunohistochemical findings in a synanthropic marsupial, the white-eared opossum (Didelphis albiventris), inhabiting peri-urban areas of north-central Parana, Southern Brazil. Molecular techniques identified the viral RNA in the lungs and kidneys. Histopathologic evaluation of these tissues revealed interstitial pneumonia in the lungs with lymphocytic nephritis and tubular necrosis in the kidneys. Immunohistochemistry assays detected positive intralesional immunoreactivity to N protein of FeMV within the lungs and kidneys. A FeMV opossum strain was isolated in Crandell Rees feline kidney lineage cells, resulting in syncytia formation and cell death. Therefore, these results support the ability of FeMV to infect other mammal species and reinforce the possibility of the opossum to be a disseminator of this virus among domestic and wild animals.

Feline Morbillivirus Infection in Domestic Cats: What Have We Learned So Far?

Feline morbillivirus (FeMV) was identified for the first time in stray cats in 2012 in Hong Kong and, since its discovery, it was reported in domestic cats worldwide. Although a potential association between FeMV infection and tubulointerstitial nephritis (TIN) has been suggested, this has not been proven, and the subject remains controversial. TIN is the most frequent histopathological finding in the context of feline chronic kidney disease (CKD), which is one of the major clinical pathologies in feline medicine. FeMV research has mainly focused on defining the epidemiology, the role of FeMV in the development of CKD, and its in vitro tropism, but the pathogenicity of FeMV is still not clear, partly due to its distinctive biological characteristics, as well as to a lack of a cell culture system for its rapid isolation. In this review, we summarize the current knowledge of FeMV infection, including genetic diversity of FeMV strains, epidemiology, pathogenicity, and clinicopathological findings observed in naturally infected cats.

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.

Development of TaqMan-based real-time RT-PCR assay based on N gene for the quantitative detection of feline morbillivirus

Background

Morbilliviruses are categorized under the family of Paramyxoviridae and have been associated with severe diseases, such as Peste des petits ruminants, canine distemper and measles with evidence of high morbidity and/or could cause major economic loss in production of livestock animals, such as goats and sheep. Feline morbillivirus (FeMV) is one of the members of Morbilliviruses that has been speculated to cause chronic kidney disease in cats even though a definite relationship is still unclear. To date, FeMV has been detected in several continents, such as Asia (Japan, China, Thailand, Malaysia), Europe (Italy, German, Turkey), Africa (South Africa), and South and North America (Brazil, Unites States). This study aims to develop a TaqMan real-time RT-PCR (qRT-PCR) assay targeting the N gene of FeMV in clinical samples to detect early phase of FeMV infection.

Results

A specific assay was developed, since no amplification was observed in viral strains from the same family of Paramyxoviridae, such as canine distemper virus (CDV), Newcastle disease virus (NDV), and measles virus (MeV), and other feline viruses, such as feline coronavirus (FCoV) and feline leukemia virus (FeLV). The lower detection limit of the assay was 1.74 × 10⁴ copies/μL with Cq value of 34.32 ± 0.5 based on the cRNA copy number. The coefficient of variations (CV) values calculated for both intra- and inter-assay were low, ranging from 0.34–0.53% and 1.38–2.03%, respectively. In addition, the clinical sample evaluation using this assay showed a higher detection rate, with 25 (35.2%) clinical samples being FeMV-positive compared to 11 (15.5%) using conventional RT-PCR, proving a more sensitive assay compared to the conventional RT-PCR.

Conclusions

The TaqMan-based real-time RT-PCR assay targeting the N gene described in this study is more sensitive, specific, rapid, and reproducible compared to the conventional RT-PCR assay targeting the N gene, which could be used to detect early infection in cats.

Molecular characterization of Feline paramyxovirus and Feline morbillivirus in cats from Brazil

This study is aimed at detecting Feline paramyxovirus (FPaV) and Feline morbillivirus (FeMV) in 35 urine samples from domestic cats, collected in 2019, with or without clinical signs of uropathies using a reverse transcription-polymerase chain reaction (RT-PCR) followed by semi-nested polymerase chain reaction (SN-PCR) assays to amplify a partial paramyxovirus L gene. Eight (22.9%) out of the 35 urine samples were positive for paramyxoviruses. Sequencing and phylogenetic analyses revealed that three samples were positive for FPaV, four samples were positive for FeMV, and it was not possible to determine which virus was present in one RT-SN-PCR positive urine sample. FPaV strains showed 100% nucleotide (nt) identity with each other and 97% nt identity with a Japanese 163 FPaV strain. The FeMV strains showed 85.9% nt identity with each other; three strains were similar to previously described Brazilian FeMV strains, and one strain clustered in a different branch of the phylogenetic tree together with the first described Chinese FeMV strain. This study provides the first description of FPaV strains in cats from Brazil and provides new information about the molecular characteristics of FPaV and FeMV strains circulating in domestic cats in Brazil.

High genetic diversity of paramyxoviruses infecting domestic cats in Western Brazil

Feline morbillivirus was discovered in 2012 in cats from Hong Kong, and it was initially found to be associated with chronic kidney disease. Although subsequent molecular surveys showed a common occurrence in cat populations from distinct countries, there were controversial results regarding the relationship between viral shedding through urine and reduced kidney function. In this study, 276 domestic cats of diverse origins from Western Brazil had their urine evaluated for the presence of paramyxoviral RNA by reverse transcription seminested PCR and direct sequencing. Additionally, a selected Brazilian feline morbillivirus strain was isolated in Crandell Rees feline kidney cells, and a nearly complete genome sequence was obtained. To assess the kidney function of all cats, serum biochemistry screening and standard urinalysis were performed. Our results revealed a relatively high paramyxovirus-positive rate (34.7%) in the evaluated cats although there was not a statistical association between the shedding of viral RNA through urine and kidney disease. Direct sequencing of partial fragments of the L gene demonstrated high genetic diversity among strains detected in cats in this study, since both feline morbillivirus RNA and feline paramyxovirus RNA were frequently shed in urine. Phylogenetic reconstruction based on partial amino acid sequences of the L gene showed that Brazilian feline paramyxovirus strains were genetically diverse since they grouped into two distinct subclusters; one subcluster contained three strains identified in Germany, while the second contained Japanese strain 163, which was recently classified in the Jeilongvirus genus of the Paramyxoviridae family. In contrast, the Brazilian feline morbillivirus strain FeMV/BR_Boni, herein characterized by nearly complete genome sequencing, was classified in the Morbillivirus genus with other strains previously identified as genotype 1. In conclusion, urinary excretion of diverse paramyxoviral RNA is frequent in cats of different origins from Western Brazil, but viral infection is not related to altered kidney function.

Identification of Novel Feline Paramyxoviruses in Guignas (Leopardus guigna) from Chile

The family of paramyxoviruses has received growing attention as several new species have been identified recently, notably two different clusters in domestic cats, designated as feline morbillivirus (FeMV) and feline paramyxovirus (FPaV). Their phylogenetic origin and whether wild felids also harbor these viruses are currently unknown. Kidney samples from 35 guignas (Leopardus guigna), a wild felid from Chile, were investigated for paramyxoviruses using consensus-RT-PCR. In addition, thirteen serum samples of guignas were screened for the presence of FeMV-specific antibodies by an immunofluorescence assay (IFA). Viral RNA was detected in 31% of the kidney samples. Phylogenetic analyses revealed two well-supported clusters, related to isolates from domestic cats, rodents and bats. No significant histopathology changes were recorded in infected guignas. Serology identified two samples which were positive for FeMV-specific antibodies. Our study highlights the diversity of paramyxovirus infections in felids with special emphasis on guignas from Chile.

High seroprevalence of feline morbilliviruses in free-roaming domestic cats in Chile

Feline morbillivirus infections have gained increased attention due to repeated reports of their association with urinary tract disease in cats. In the present study, 112 serum samples from free-roaming domestic cats in Chile were tested for antibodies against feline morbillivirus genotypes 1 and 2 (FeMV-1 and FeMV-2) using an indirect immunofluorescence assay. In total, 63% of the animals showed antibodies against one or both FeMV genotypes. Antibodies directed exclusively against FeMV-2 were significantly more prevalent in male cats. The correlation of sex and FeMV-2 infection might give insight into potential routes of transmission. We provide, for the first time, serological data on FeMV in Chile.

Increased proportion of apoptotic cells in cat kidney tissues infected with feline morbillivirus

In order to study potential pathogenic mechanisms of feline morbillivirus (FeMV) in infected kidney cells, we performed a terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and an immunofluorescence assay (IFA) with an anti-FeMV P protein antibody on a total of 38 cat kidney tissues, 12 of which were positive for FeMV. Among these samples, we detected significantly larger numbers of apoptotic cells in FeMV-positive tissues than in FeMV-negative tissues, and in these tissues, a substantial percentage of TUNEL-positive (TUNEL⁺) cells contained the FeMV P protein (mean, 37.4; range, 17.4-82.9), suggesting that induction of apoptosis may be an important mechanism for pathological changes associated with FeMV infection in cat kidney tissues.

Feline Morbillivirus Infection Associated With Tubulointerstitial Nephritis in Black Leopards (Panthera pardus)

Feline morbillivirus (FeMV) is an emerging RNA virus in the Paramyxoviridae family that was recently discovered in domestic cats ( Felis catus). To date, 2 genotypes (FeMV-1 and FeMV-2) have been detected in cats from various countries, and FeMV-1 is recognized as a pathogen associated with nephritis. However, information regarding the pathological roles and potential transmission to other felids is limited. In this article, we describe the identification of FeMV in 2 black leopards ( Panthera pardus) in Thailand that showed severe azotemia and tubulointerstitial nephritis. Molecular analysis of the partial coding sequence of the L gene revealed that these leopard FeMV strains were genetically close to the FeMV-1 isolate from domestic Thai cats. Immunohistochemistry and immunofluorescence analyses using polyclonal IgG antibodies against the FeMV matrix (M) protein showed FeMV-M antigen in renal tubular epithelial cells. These analyses also showed infiltrating lymphocytes in the renal parenchymal lesions and in the cytoplasm of lymphoid cells residing in the spleen, suggesting viral tropism and a possible pathological role. These findings are the first evidence that indicates that the black leopard could be a possible host for FeMV infection. As for other cats, the role of FeMV as a potential cause of renal disease remains to be established. The pathogenesis of FeMV infection in black leopards, or in other wild felids, through a viral transmission mechanism warrants further investigation.

Molecular epidemiology and genome analysis of feline morbillivirus in household and shelter cats in Thailand

Background

Feline morbillivirus (FeMV) has been discovered in domestic cats associated with tubulointerstitial nephritis, but FeMV is also detected in healthy cats. This research aimed to identify and characterize the FeMV strains detected in a Thai cat population.

Results

Two-hundred and ninety-two samples (131 urine and 161 blood) derived from 261 cats (61 sheltered and 200 household cats) were included for investigating the FeMV prevalence using real-time reverse transcription PCR. The overall prevalence of FeMV detection was 11.9% (31/261) among both samples, which accounted for 14.5% (19/131) and 7.5% (12/161) of the urine and blood samples, respectively. Among the FeMV-PCR positive cats, the FeMV-detected prevalence was insignificantly associated with healthy cats (58.1%; 18/31) or urologic cats (41.9%; 13/31). Full-length genome analysis of these FeMV-Thai strains revealed that their genomes clustered together in the FeMV-1A clade with up to 98.5% nucleotide identity. Selective pressure analysis showed that overall FeMV-1 has undergone negative selection, while positive selection sites were more frequently observed in the phosphoprotein gene.

Conclusions

The detected FeMV infections in the Thai cat population were not correlated with urologic disorders, although the virus was more detectable in urine samples. The genetic patterns among the FeMV-1 Thai strains were more consistent. A large-scale study of FeMV in Thai cat samples is needed for further elucidation.

First report of feline morbillivirus in mainland China

Feline morbillivirus (FeMV) is an emerging member of the family Paramyxoviridae that is suspected to be involved in chronic kidney disease (CKD). FeMV was first discovered in Hong Kong in 2012 and has subsequently been detected in many countries. However, the prevalence of FeMV in mainland China is still unclear. To clarify the present status and examine the genetic diversity of FeMV in mainland China, in this study, we collected cat urine samples in veterinary hospitals in Guangdong Province in 2017 and 2018. Using reverse transcription (RT)-PCR, we found that the urine of six out of 64 cats tested positive for FeMV RNA. Sequencing and genetic analysis of the FeMV L gene showed that FeMV in mainland China is genetically diverse, and phylogenetic analysis showed that the viruses segregated into two clusters. Two isolates, GD5 and GD6, grouped in a branch that was separate from the one containing other previously reported FeMV isolates. These results will contribute to a better understanding of the evolution of FeMV in China.

Early Renal Involvement in Cats with Natural Feline Morbillivirus Infection

Simple Summary

Feline morbillivirus is a newly discovered paramyxovirus infecting domestic cats. Its pathogenetic role in domestic cats is still debated, however some evidences suggest a potential involvement of this novel feline virus in the pathogenesis of feline chronic kidney disease. In this study, clinical data of cats infected by morbillivirus were retrospectively reviewed and compared with data obtained from healthy cats and cats affected by chronic kidney disease. The results of the present study suggest that this infection can be associated with the presence of a sub-clinical kidney damage and with different grades of renal dysfunction in cats younger than those typically affected by chronic kidney disease.

Abstract

Feline morbillivirus (FeMV) is a newly discovered paramyxovirus infecting domestic cats and its role in the pathogenesis of feline chronic kidney disease (CKD) has been suggested, however not confirmed. The primary aim of the study was to evaluate the renal damage associated with FeMV infection in cats. In this retrospective study, clinical and clinicopathological data were compared among 14 FeMV naturally infected, 21 CKD and 22 healthy cats. FeMV positive cats had serum chemistry analytes and main urine chemistry results similar to the healthy subjects. FeMV positive cats had significantly decreased urine specific gravity (median 1054, range 1022–1065) and urine creatinine (median 227.23 mg/dL, range 83.02–489.75) when compared with healthy cats (median 1067, range 1040–1080, p < 0.001; median 406.50 mg/dL, range 195.32–575.58; p < 0.001, respectively). Urine protein:creatinine ratio (UPC) results of FeMV and CKD were not different (median 0.20, range 0.08–1.03; median 0.23, range 0.10–0.80, respectively), however UPC results were significantly increased in both groups, if compared with healthy cats (median 0.1, range 0.04–0.250, p < 0.01). Based on clinical data, serum creatinine concentration, urine specific gravity and UPC results, CKD was suspected by clinicians in 3/14 FeMV cats. Urine protein sodium-dodecyl-sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in 10/13 (77%) FeMV cats indicated a tubular pattern, with a decrease of uromodulin and an increase in the number and intensity of low molecular weight proteins. FeMV infection can be associated with different grades of renal dysfunction ranging from mild tubular proteinuria with less concentrated urine to azotemia in cats younger than those typically affected by CKD.

Feline Morbillivirus, a New Paramyxovirus Possibly Associated with Feline Kidney Disease

Feline morbillivirus (FeMV) was first isolated in stray cats in Hong Kong in 2012. Since its discovery, the virus has been reported in domestic cats worldwide, including in Hong Kong, Japan, Italy, US, Brazil, Turkey, UK, Germany, and Malaysia. FeMV is classified in the Morbillivirus genus within the Paramyxoviridae family. FeMV research has focused primarily on determining the host range, symptoms, and characteristics of persistent infections in vitro. Importantly, there is a potential association between FeMV infection and feline kidney diseases, such as tubulointerstitial nephritis (TIN) and chronic kidney diseases (CKD), which are known to significantly affect feline health and survival. However, the tropism and viral entry mechanism(s) of FeMV remain unknown. In this review, we summarize the FeMV studies up to date, including the discoveries of various FeMV strains, basic virology, pathogenicity, and disease signs.

Metagenomics revealing new virus species in farm and pet animals and aquaculture

Viral metagenomics is slowly taking over the traditional and widely used molecular techniques for the investigation of pathogenic viruses responsible for illness and inflicting great economic burden on the farm animal industry. Owing to the continued improvements in sequencing technologies and the dramatic reduction of per base costs of sequencing the use of next generation sequencing have been key factors in this progress. Discoveries linked to viral metagenomics are expected to be beneficial to the field of veterinary medicine starting from the development of better diagnostic assays to the design of new subunit vaccines with minimal investments. With these achievements the research has taken a giant leap even toward the better healthcare of animals and, as a result, the animal sector could be growing at an unprecedented pace.

Epidemiology, pathological aspects and genome heterogeneity of feline morbillivirus in Italy

Feline morbillivirus (FeMV) is an emerging morbillivirus first described in cats less than a decade ago. FeMV has been associated with chronic kidney disease of cats characterized by tubulointerstitial nephritis (TIN), although this aspect is still controversial and not demonstrated with certainty. To investigate FeMV prevalence and genomic characteristics, an epidemiological survey was conducted in a total number of 127 household cats originating from two Italian regions, Abruzzi and Emilia-Romagna. A total number of 69 cats originating from three feline colonies were also enrolled for the study. Correlation with TIN was investigated by employing a total number of 35 carcasses. Prevalence of FeMV RNA was higher in urine samples collected from cats of colonies (P = 31.8%, CI 95% 22.1-43.6) compared to household cats (P = 8.66%, CI 95% 4.9-14.9) and in young and middle-aged cats while prevalence of FeMV Abs was higher in old cats. Sequences obtained straight from infected biological samples, either partial or complete, cluster into two clades within FeMV genotype 1, distantly related to FeMV genotype 2. Immunohistochemistry analysis of kidney sections of FeMV RNA positive cats revealed immunoreactivity within epithelial cells of renal tubuli and inflammatory cells. However, statistically significant association between FeMV and renal damages, including TIN, was not demonstrated (p= 0.0695, Fisher exact test). By virus histochemistry performed with FeMV-negative feline tissues and a FeMV isolate, tropism for different cellular types such as inflammatory cells residing in blood vessels of kidney and brain, airway epithelial cells, alveolar macrophages and to a lesser extent, the central nervous system, was demonstrated. Additional studies are warranted in order to establish viral tropism and immune response during the early phases of infection and to disentangle the role of FeMV in co-infection processes.

Molecular detection and characterisation of feline morbillivirus in domestic cats in Malaysia

Feline morbillivirus (FeMV), a novel virus from the family of Paramyxoviridae, was first identified in stray cat populations. The objectives of the current study were to (i) determine the molecular prevalence of FeMV in Malaysia; (ii) identify risk factors associated with FeMV infection; and (iii) characterise any FeMV isolates by phylogenetic analyses. Molecular analysis utilising nested RT-PCR assay targeting the L gene of FeMV performed on either urine, blood and/or kidney samples collected from 208 cats in this study revealed 82 (39.4%) positive cats. FeMV-positive samples were obtained from 63/124 (50.8%) urine and 20/25 (80.0%) kidneys while all blood samples were negative for FeMV. In addition, from the 35 cats that had more than one type of samples collected (blood and urine; blood and kidney; blood, urine and kidney), only one cat had FeMV RNA in the urine and kidney samples. Risk factors such as gender, presence of kidney-associated symptoms and cat source were also investigated. Male cats had a higher risk (p = 0.031) of FeMV infection than females. In addition, no significant association (p = 0.083) was observed between the presence of kidney-associated symptoms with FeMV status. From the 82 positive samples, FeMV RNA was detected from 48/82 (58.5%) pet cats and 34/126 (27.0%) shelter cats (p < 0.0001). Partial L and N gene sequencing of the RT-PCR-positive samples showed 85-99% identity to the published FeMV sequences and it was significantly different from all other morbilliviruses. A phylogenetic analysis of the identified Malaysian FeMVs was performed with isolates from Japan, Thailand and China. Molecular characterisation revealed high relatedness of the Malaysian isolates with other Asian FeMVs, indicating that the virus had been circulating only within the region. Therefore, this study confirmed the existence of FeMV among domestic cats in Malaysia. The findings suggest further characterisation of the local isolates, including the whole genome sequencing and that studies at determining the direct consequences of FeMV infection in domestic cats are needed.

Modified Dose Efficacy Trial of a Canine Distemper-Measles Vaccine for Use in Rhesus Macaques (Macaca mulatta)

Measles virus causes a highly infectious disease in NHP. Clinical signs range from asymptomatic to fatal, although measles virus is most well-known for its characteristic generalized maculopapular rash. Along with appropriate quarantine practices, restricted human access, and appropriate personal protective equipment, vaccines are used to combat the risk of infection. The canine distemper-measles vaccine (CDMV), administered at the manufacturer's standard dose (1.0 mL IM), has been shown to be effective against clinical measles disease in rhesus macaques (Macaca mulatta). The goal of the current study was to test whether doses smaller than the manufacturer's recommended dose stimulated adequate antibody production to protect against infection. We hypothesized that either 0.25 or 0.5 mL IM of CDMV would stimulate antibody production comparable to the manufacturer's recommended dose. We found that the 0.25-mL dose was less effective at inducing antibodies than either the standard (1.0 mL) or 0.5-mL dose, which both yielded similar titers. The primary implication of this study informs balancing resource allocation and providing efficacious immunity. By using half the manufacturer-recommended dose, the 50% cost reduction may provide sufficient monetary incentive to implement, maintain, or modify measles vaccination programs at NHP facilities.

Feline morbillivirus in Northern Italy: prevalence in urine and kidneys with and without renal disease

Feline morbillivirus (FeMV) is an emerging virus that was first described in Hong Kong in 2012. Several reports suggested the epidemiological association of FeMV infection with chronic kidney disease (CKD) in cats. The aim of this study was to investigate the presence and the genetic diversity of FeMV as well as the relationship between FeMV infection and CKD in cats from Northern Italy. Urine (n = 81) and kidney samples (n = 27) from 92 cats admitted to the Veterinary Teaching Hospital of the University of Milan between 2014 and 2017 were investigated for FeMV infection. FeMV RNA was detected in one urine sample (1.23%; 95% CI: 0.03-6.68%) and in two kidneys (7.40%; 95% CI: 0.91-24.28%). FeMV RNA was revealed only in urine or kidneys of cats without evidence of CKD. Phylogenetic analysis showed that the three strains clustered with FeMV strains retrieved from public database, forming a distinct sub-cluster of FeMV. The presence of distinct genotypes of FeMV found in this study is in accordance with previous studies demonstrating that FeMV strains are genetically diverse. A clear relationship between the presence of FeMV infection and CKD in the cats from Northern Italy was not observed, confirming recent reports that do not support the hypothesis that FeMV infection is associated with the development of CKD.

The Dynamic Nature of Canine and Feline Infectious Disease Risks in the Twenty-first Century

Canine and feline infectious diseases are constantly changing in frequency and location. Numerous drivers or determinants of these changes are suspected, including emergence of new pathogens; change in virulence and resistance of existing pathogens; change in land use, climate, and weather; travel and trade; habitat destruction and urbanization; change in animal-animal contact networks; host susceptibility; availability and uptake of prevention measures; and change in ability to detect pathogens and track diseases. This article explores each of these proposed drivers and examines examples of feline and canine diseases likely to be influenced by them.

A New Genotype of Feline Morbillivirus Infects Primary Cells of the Lung, Kidney, Brain and Peripheral Blood

Paramyxoviruses comprise a large number of diverse viruses which in part give rise to severe diseases in affected hosts. A new genotype of feline morbillivirus, tentatively named feline morbillivirus genotype 2 (FeMV-GT2), was isolated from urine of cats with urinary tract diseases. Whole genome sequencing showed about 78% nucleotide homology to known feline morbilliviruses. The virus was isolated in permanent cell lines of feline and simian origin. To investigate the cell tropism of FeMV-GT2 feline primary epithelial cells from the kidney, the urinary bladder and the lung, peripheral blood mononuclear cells (PBMC), as well as organotypic brain slice cultures were used for infection experiments. We demonstrate that FeMV-GT2 is able to infect renal and pulmonary epithelial cells, primary cells from the cerebrum and cerebellum, as well as immune cells in the blood, especially CD4⁺ T cells, CD20⁺ B cells and monocytes. The cats used for virus isolation shed FeMV-GT2 continuously for several months despite the presence of neutralizing antibodies in the blood. Our results point towards the necessity of increased awareness for this virus when clinical signs of the aforementioned organs are encountered in cats which cannot be explained by other etiologies.

The switch between acute and persistent paramyxovirus infection caused by single amino acid substitutions in the RNA polymerase P subunit

Paramyxoviruses can establish persistent infections both in vitro and in vivo, some of which lead to chronic disease. However, little is known about the molecular events that contribute to the establishment of persistent infections by RNA viruses. Using parainfluenza virus type 5 (PIV5) as a model we show that phosphorylation of the P protein, which is a key component of the viral RNA polymerase complex, determines whether or not viral transcription and replication becomes repressed at late times after infection. If the virus becomes repressed, persistence is established, but if not, the infected cells die. We found that single amino acid changes at various positions within the P protein switched the infection phenotype from lytic to persistent. Lytic variants replicated to higher titres in mice than persistent variants and caused greater infiltration of immune cells into infected lungs but were cleared more rapidly. We propose that during the acute phases of viral infection in vivo, lytic variants of PIV5 will be selected but, as the adaptive immune response develops, variants in which viral replication can be repressed will be selected, leading to the establishment of prolonged, persistent infections. We suggest that similar selection processes may operate for other RNA viruses.

Novel feline viruses: Emerging significance of gammaherpesvirus and morbillivirus infections

PRACTICAL RELEVANCE

New technologies capable of sequencing the genetic material in any given biological sample, combined with computer-based algorithms for sequence assembly and analysis, have revolutionised infectious disease research. The rate at which novel viruses are being discovered now exceeds our understanding of their clinical relevance. Novel viruses may contribute to diseases that are major causes of feline morbidity and mortality, including cancer and chronic kidney disease. The identification of new viral pathogens raises the prospect of not only improved patient outcomes through specific treatment but even disease prevention through viral control measures.

CLINICAL CHALLENGES

It can be difficult to determine the role of a novel virus in disease development. Disease may be an occasional outcome, often years after infection. A high prevalence of infection in the general population can make disease associations harder to identify and almost impossible to rule out. Host cofactors such as immune dysfunction, genetic background or coinfections may be required for manifestation of disease, and one virus species may be linked to a range of pathological sequelae. Establishing causality relies on evaluating accumulating evidence from multiple investigations, which is often hard to access by practitioners.

GLOBAL IMPORTANCE

The worldwide distribution of gammaherpesvirus and morbillivirus infections in domestic cats underlines the potential of these viruses to negatively impact feline health and welfare globally.

EVIDENCE BASE

This review relies on grade la-III evidence.

Association of feline morbillivirus infection with defined pathological changes in cat kidney tissues

Feline morbillivirus (FeMV) is an emerging member of morbillivirus discovered in 2012. Although association of FeMV infection with kidney diseases in cats has been suggested, the pathogenicity of the virus has not been clear to date. To study the association between FeMV infection and pathological changes in kidney tissues of infected cats, we performed immunohistochemistry and immunofluorescent assays to detect FeMV antigens and analyzed the effect of FeMV infection on the pathological changes in the kidney tissues. In 38 kidney tissue samples from cats, some tissue injury scores were significantly higher when the FeMV antigens were detected, especially those for the tubular tissues in which the FeMV antigens were mostly localized. Pathological changes associated with the FeMV antigens included the ones typically found in chronic kidney diseases, such as interstitial cell infiltration, glomerulosclerosis, tubular atrophy and fibrosis. We also detected some feline IgG localizations in glomerular tissues, though co-localization or significant association with the FeMV antigens were not found. Our study confirms the association of FeMV infection with some kidney tissue injuries and provides additional information about roles of FeMV infection in chronic kidney diseases.

A real-time RT-PCR assay for molecular identification and quantitation of feline morbillivirus RNA from biological specimens

The aim of this study was to develop a real-time RT-PCR to detect and quantitate feline morbillivirus (FeMV) RNA in biological samples. Primers and probe were targeted on a conserved region of FeMV P/V/C gene. To validate the assay with field samples, a total number of specimens of cats have been recruited including 264 urine and blood samples and compared with a generic RT-PCR targeting the L protein encoding gene of morbilliviruses. In addition, 385 tissue samples from 35 carcasses of cats have been also employed. RNA titres were low in all tested samples. Results also indicated the absence of cross-reaction with related morbilliviruses and existing pathogens of cats. In tissues with low levels of FeMV RNA, the presence of viral antigen was also evidenced by immunohistochemistry targeting the N viral protein. This newly described assay allows for a rapid, accurate and reliable quantitative detection of FeMV RNA that can be applied for diagnostics and research studies.

Detection and seroprevalence of morbillivirus and other paramyxoviruses in geriatric cats with and without evidence of azotemic chronic kidney disease

BACKGROUND

Feline morbillivirus (FeMV) is associated with the presence of tubulo-interstitial nephritis (TIN) in cats, however the seroprevalence of FeMV in the UK and the association between the presence of FeMV and renal azotemia is unknown HYPOTHESIS/OBJECTIVES: To identify whether paramyxoviruses are present in urine samples of geriatric cats and to develop an assay to assess FeMV seroprevalence. To investigate the relationship between both urinary paramyxovirus (including FeMV) excretion and FeMV seroprevalence and azotemic chronic kidney disease (CKD).

ANIMALS

Seventy-nine cats (40 for FeMV detection; 72 for seroprevalence).

METHODS

Retrospective cross-sectional, case control study. Viral RNA was extracted from urine for RT-PCR. PCR products were sequenced for virus identification and comparison. The FeMV N protein gene was cloned and partially purified for use as an antigen to screen cat sera for anti-FeMV antibodies by Western Blot.

RESULTS

Feline morbillivirus RNA from five distinct morbilliviruses were identified. Detection was not significantly different between azotemic CKD (1/16) and nonazotemic groups (4/24; P = .36). Three distinct, non-FeMV paramyxoviruses were present in the nonazotemic group but their absence from the azotemic group was not statistically significant (P = .15). 6/14 (43%) azotemic cats and 40/55 (73%) nonazotemic cats were seropositive (P = .06).

CONCLUSIONS AND CLINICAL IMPORTANCE

Feline morbillivirus was detected in cats in the UK for the First time. However, there was no association between virus prevalence or seropositivity and azotemic CKD. These data do not support the hypothesis that FeMV infection is associated with the development of azotemic CKD in cats in the UK.

First Complete Genome Sequence of a Feline Morbillivirus Isolate from Germany

The first cell culture isolation and whole-genome sequence of a feline morbillivirus from Germany are described here. Phylogenetic analysis revealed highest similarity to isolates from Japan and a more distant relationship to strains from Italy, Hong Kong, and the United States. Therefore, feline morbilliviruses should be divided into two different genotypes.

Morbillivirus Pathogenesis and Virus-Host Interactions

Despite the availability of safe and effective vaccines against measles and several animal morbilliviruses, they continue to cause regular outbreaks and epidemics in susceptible populations. Morbilliviruses are highly contagious and share a similar pathogenesis in their respective hosts. This review provides an overview of morbillivirus history and the general replication cycle and recapitulates Morbillivirus pathogenesis focusing on common and unique aspects seen in different hosts. It also summarizes the state of knowledge regarding virus-host interactions on the cellular level with an emphasis on viral interference with innate immune response activation, and highlights remaining knowledge gaps.

Frequency, clinicopathological features and phylogenetic analysis of feline morbillivirus in cats in Istanbul, Turkey

Objectives The aim of the study was to investigate feline morbillivirus (FmoPV) frequency, phylogeny and associated pathology in cats in Istanbul, Turkey. Methods Samples from sick (n = 96) and dead ( n = 15) cats were analysed using reverse transcription PCR. Blood and urine analyses and histopathology were also performed. Results FmoPV RNA was detected in six cats (5.4%), including three sick (in the urine) and three dead cats (tissues). A significantly greater proportion of FmoPV RNA-positive cats had street access compared with non-infected cats. Blood samples from the morbillivirus-positive cats were negative for morbillivirus RNA. Tubular parenchymal cells, lymphoid and plasma cells in kidney and hepatocytes, lymphoid and plasma cells in liver from dead cats were also positive by immunohistochemistry for the viral N protein. Two FmoPV-positive cats were also positive for feline coronavirus RNA and one cat for feline immunodeficiency virus RNA and feline leukaemia virus proviral DNA. Phylogenetic analysis of the six FmoPV-positive cats showed that the strains were grouped into cluster D and had high similarity (98.5-100%) with strains from Japan and Germany. In the three FmoPV RNA-positive sick cats, respiratory, urinary and digestive system signs were observed as well as weight loss, fever and depression in some cats. Similar clinical signs were also seen in the morbillivirus RNA-negative sick cats. FmoPV RNA-positive cats had lower median red blood cell count, haemoglobin, albumin, albumin/globulin and urobilinogen and higher alanine transaminase, alkaline phosphatase and bilirubin compared with non-infected cats. Significant histopathology of FmoPV RNA-positive dead cats included tubulointerstitial nephritis characterised by severe granular and vacuolar degeneration of the epithelial cells of the cortical and medullary tubules as well as mononuclear cell infiltrates. Widespread lymphoid cell infiltrates were detected in the renal cortex and medullary regions of the kidneys. Cellular infiltration, cholangiohepatitis and focal necrosis in the liver were also found. Although virus-infected cells were found in the kidney and liver of FmoRV RNA-positive cats, tubulointerstitial nephritis, cholangiohepatitis and focal necrosis seen in FmoRV RNA-positive cats were similar to those observed in FmoRV RNA-negative cats. Conclusions and relevance This is the first study to show the presence of FmoPV infection in cats in Turkey. Sick cats, particularly those with kidney disease, should be tested for this virus. The genotypes found in this study were similar to previously reported strains, indicating that circulating morbilliviruses in Turkey are conserved.

Future research to underpin successful peste des petits ruminants virus (PPRV) eradication

Peste des petits ruminants virus (PPRV) is a significant pathogen of small ruminants and is prevalent in much of Africa, the Near and Middle East and Asia. Despite the availability of an efficacious and cheap live-attenuated vaccine, the virus has continued to spread, with its range stretching from Morocco in the west to China and Mongolia in the east. Some of the world's poorest communities rely on small ruminant farming for subsistence and the continued endemicity of PPRV is a constant threat to their livelihoods. Moreover, PPRV's effects on the world's population are felt broadly across many economic, agricultural and social situations. This far-reaching impact has prompted the Food and Agriculture Organization of the United Nations (FAO) and the World Organisation for Animal Health (OIE) to develop a global strategy for the eradication of this virus and its disease. PPRV is a morbillivirus and, given the experience of these organizations in eradicating the related rinderpest virus, the eradication of PPRV should be feasible. However, there are many critical areas where basic and applied virological research concerning PPRV is lacking. The purpose of this review is to highlight areas where new research could be performed in order to guide and facilitate the eradication programme. These areas include studies on disease transmission and epidemiology, the existence of wildlife reservoirs and the development of next-generation vaccines and diagnostics. With the support of the international virology community, the successful eradication of PPRV can be achieved.

Idiosyncratic Mòjiāng virus attachment glycoprotein directs a host-cell entry pathway distinct from genetically related henipaviruses

In 2012, cases of lethal pneumonia among Chinese miners prompted the isolation of a rat-borne henipavirus (HNV), Mòjiāng virus (MojV). Although MojV is genetically related to highly pathogenic bat-borne henipaviruses, the absence of a conserved ephrin receptor-binding motif in the MojV attachment glycoprotein (MojV-G) indicates a differing host-cell recognition mechanism. Here we find that MojV-G displays a six-bladed β-propeller fold bearing limited similarity to known paramyxoviral attachment glycoproteins, in particular at host receptor-binding surfaces. We confirm the inability of MojV-G to interact with known paramyxoviral receptors in vitro, indicating an independence from well-characterized ephrinB2/B3, sialic acid and CD150-mediated entry pathways. Furthermore, we find that MojV-G is antigenically distinct, indicating that MojV would less likely be detected in existing large-scale serological screening studies focused on well-established HNVs. Altogether, these data indicate a unique host-cell entry pathway for this emerging and potentially pathogenic HNV.

The attachment glycoprotein (HNV-G) of henipaviruses interacts with host receptors at the cell surface and is a major determinant of species tropism. Here the authors provide structural and functional evidence that the emergent henipavirus, Mòjiang virus, uses an entry mechanism that is independent of known paramyoxviral cellular receptors.

Development of an ELISA for serological detection of feline morbillivirus infection

Feline morbillivirus (FeMV), a member of the family Paramyxoviridae, is an emerging virus that was discovered in 2012. Despite the importance of FeMV infection in cats because of its postulated involvement in kidney diseases, no simple serological assay has been reported in its detection. Here, FeMV phosphoprotein (P protein) was expressed and purified as a glutathione-S-transferase (GST)-fusion protein and used for an enzyme-linked immunosorbent assay (ELISA) to detect FeMV-specific antibodies. With a cutoff value determined by immunoblotting, anti-FeMV P protein was detected with this assay in 22 (22%) of the 100 cat plasma samples collected from various regions of Japan. This ELISA is useful for epidemiological and immunological studies, as well as for diagnosis of FeMV infection.

Within host RNA virus persistence: mechanisms and consequences

In a prototypical response to an acute viral infection it would be expected that the adaptive immune response would eliminate all virally infected cells within a few weeks of infection. However many (non-retrovirus) RNA viruses can establish 'within host' persistent infections that occasionally lead to chronic or reactivated disease. Despite the importance of 'within host' persistent RNA virus infections, much has still to be learnt about the molecular mechanisms by which RNA viruses establish persistent infections, why innate and adaptive immune responses fail to rapidly clear these infections, and the epidemiological and potential disease consequences of such infections.

Zoonotic Potential of Emerging Paramyxoviruses: Knowns and Unknowns

The risk of spillover of enzootic paramyxoviruses and the susceptibility of recipient human and domestic animal populations are defined by a broad collection of ecological and molecular factors that interact in ways that are not yet fully understood. Nipah and Hendra viruses were the first highly lethal zoonotic paramyxoviruses discovered in modern times, but other paramyxoviruses from multiple genera are present in bats and other reservoirs that have unknown potential to spillover into humans. We outline our current understanding of paramyxovirus reservoir hosts and the ecological factors that may drive spillover, and we explore the molecular barriers to spillover that emergent paramyxoviruses may encounter. By outlining what is known about enzootic paramyxovirus receptor usage, mechanisms of innate immune evasion, and other host-specific interactions, we highlight the breadth of unexplored avenues that may be important in understanding paramyxovirus emergence.

Enhanced immunosurveillance for animal morbilliviruses using vesicular stomatitis virus (VSV) pseudotypes

The measurement of virus-specific neutralising antibodies represents the “gold-standard” for diagnostic serology. For animal morbilliviruses, such as peste des petits ruminants (PPRV) or rinderpest virus (RPV), live virus-based neutralisation tests require high-level biocontainment to prevent the accidental escape of the infectious agents. In this study, we describe the adaptation of a replication-defective vesicular stomatitis virus (VSVΔG) based pseudotyping system for the measurement of neutralising antibodies against animal morbilliviruses. By expressing the haemagglutinin (H) and fusion (F) proteins of PPRV on VSVΔG pseudotypes bearing a luciferase marker gene, neutralising antibody titres could be measured rapidly and with high sensitivity. Serological responses against the four distinct lineages of PPRV could be measured simultaneously and cross-neutralising responses against other morbilliviruses compared. Using this approach, we observed that titres of neutralising antibodies induced by vaccination with live attenuated PPRV were lower than those induced by wild type virus infection and the level of cross-lineage neutralisation varied between vaccinates. By comparing neutralising responses from animals infected with either PPRV or RPV, we found that responses were highest against the homologous virus, indicating that retrospective analyses of serum samples could be used to confirm the nature of the original pathogen to which an animal had been exposed. Accordingly, when screening sera from domestic livestock and wild ruminants in Tanzania, we detected evidence of cross-species infection with PPRV, canine distemper virus (CDV) and a RPV-related bovine morbillivirus, suggesting that exposure to animal morbilliviruses may be more widespread than indicated previously using existing diagnostic techniques.

Epidemiological and pathological study of feline morbillivirus infection in domestic cats in Japan

BACKGROUND

Feline morbillivirus (FmoPV) is a novel paramyxovirus found to infect domestic cats. FmoPV has been isolated in several countries in Asia and Europe and is considered to have genetic diversity. Also, it is suspected to be associated with feline renal diseases including tubulointerstitial nephritis (TIN), which affects domestic cats with a high incidence rate.

RESULTS

To clarify the state of FmoPV infection among domestic cats in Japan, an epidemiological survey was conducted. Twenty-one out of 100 cats were found to have serum antibodies (Ab) against FmoPV-N protein by indirect immunofluorescence assay (IF) using FmoPV-N protein-expressing HeLa cells. Twenty-two of the cats were positive for FmoPV RNA in the urine and/or renal tissues. In total, 29 cats were positive for Ab and/or viral RNA. These FmoPV-infected cats were classified into three different phases of infection: RNA+/Ab + (14 cats), RNA+/Ab- (8 cats) and RNA-/Ab + (7 cats). In immunohistochemistry (IHC), 19 out of 29 cats were positive for FmoPV-N protein in kidney tissues; however, the FmoPV-N protein was located in the inflammatory lesions with severe grade in only four out of the 19 cats. Since 15 out of 29 infected cats were positive for viral RNA and Ab, approximately half of the infected cats were persistently infected with FmoPV.

CONCLUSIONS

A statistically significant difference was observed between infection of FmoPV and the presence of inflammatory changes in renal lesions, indicating a relationship between FmoPV infection and feline renal diseases. However, we could not obtain histopathological evidence of a relationship between FmoPV infection and TIN.