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.

Delineating morbillivirus entry, dissemination and airborne transmission by studying in vivo competition of multicolor canine distemper viruses in ferrets.

Identification of cellular receptors and characterization of viral tropism in animal models have vastly improved our understanding of morbillivirus pathogenesis. However, specific aspects of viral entry, dissemination and transmission remain difficult to recapitulate in animal models. Here, we used three virologically identical but phenotypically distinct recombinant (r) canine distemper viruses (CDV) expressing different fluorescent reporter proteins for in vivo competition and airborne transmission studies in ferrets (Mustela putorius furo). Six donor ferrets simultaneously received three rCDVs expressing green, red or blue fluorescent proteins via conjunctival (ocular, Oc), intra-nasal (IN) or intra-tracheal (IT) inoculation. Two days post-inoculation sentinel ferrets were placed in physically separated adjacent cages to assess airborne transmission. All donor ferrets developed lymphopenia, fever and lethargy, showed progressively increasing systemic viral loads and were euthanized 14 to 16 days post-inoculation. Systemic replication of virus inoculated via the Oc, IN and IT routes was detected in 2/6, 5/6 and 6/6 ferrets, respectively. In five donor ferrets the IT delivered virus dominated, although replication of two or three different viruses was detected in 5/6 animals. Single lymphocytes expressing multiple fluorescent proteins were abundant in peripheral blood and lymphoid tissues, demonstrating the occurrence of double and triple virus infections. Transmission occurred efficiently and all recipient ferrets showed evidence of infection between 18 and 22 days post-inoculation of the donor ferrets. In all cases, airborne transmission resulted in replication of a single-colored virus, which was the dominant virus in the donor ferret. This study demonstrates that morbilliviruses can use multiple entry routes in parallel, and co-infection of cells during viral dissemination in the host is common. Airborne transmission was efficient, although transmission of viruses expressing a single color suggested a bottleneck event. The identity of the transmitted virus was not determined by the site of inoculation but by the viral dominance during dissemination.

Could this be measles?

Infection with the measles virus causes an unpleasant disease with many potentially serious complications. It is predominantly a childhood illness but can affect any age. Measles is extraordinarily contagious, but immunisation with measles containing vaccine provides comprehensive protection. An international programme of universal immunisation from the mid-1980s has been very effective; measles was declared eliminated in the USA nearly two decades ago and became a rarity in other countries with high rates of vaccine uptake. Until recently, this was a forgotten disease in high-income countries, but paediatricians, emergency and primary care physicians worldwide are now encountering measles with increased frequency. Attributed to international travel and pockets of vaccine hesitancy locally, new outbreaks of measles have been recorded in many regions thought to have been free of the disease. Because it was previously so uncommon, measles presents a diagnostic challenge and an unrecognised case may cause infection to spread among communities. The present article presents a case of confirmed measles infection and discusses the epidemiology, clinical features, investigation, management and prevention of measles.

Dynamics of a morbillivirus at the domestic-wildlife interface: Canine distemper virus in domestic dogs and lions.

Morbilliviruses cause many diseases of medical and veterinary importance, and although some (e.g., measles and rinderpest) have been controlled successfully, others, such as canine distemper virus (CDV), are a growing concern. A propensity for host-switching has resulted in CDV emergence in new species, including endangered wildlife, posing challenges for controlling disease in multispecies communities. CDV is typically associated with domestic dogs, but little is known about its maintenance and transmission in species-rich areas or about the potential role of domestic dog vaccination as a means of reducing disease threats to wildlife. We address these questions by analyzing a long-term serological dataset of CDV in lions and domestic dogs from Tanzania's Serengeti ecosystem. Using a Bayesian state-space model, we show that dynamics of CDV have changed considerably over the past three decades. Initially, peaks of CDV infection in dogs preceded those in lions, suggesting that spill-over from dogs was the main driver of infection in wildlife. However, despite dog-to-lion transmission dominating cross-species transmission models, infection peaks in lions became more frequent and asynchronous from those in dogs, suggesting that other wildlife species may play a role in a potentially complex maintenance community. Widespread mass vaccination of domestic dogs reduced the probability of infection in dogs and the size of outbreaks but did not prevent transmission to or peaks of infection in lions. This study demonstrates the complexity of CDV dynamics in natural ecosystems and the value of long-term, large-scale datasets for investigating transmission patterns and evaluating disease control strategies.

Western blot expression of 5-lipoxygenase in the brain from striped dolphins (stenella coeruleoalba) and bottlenose dolphins (tursiops truncatus) with or without encephalitis/meningo-encephalitis of infectious nature.

Dolphin Morbillivirus (DMV), Toxoplasma gondii and Brucella ceti are pathogens of major concern for wild cetaceans. Although a more or less severe encephalitis/meningo-encephalitis may occur in striped dolphins (Stenella coeruleoalba) and bottlenose dolphins (Tursiops truncatus) infected by the aforementioned agents, almost no information is available on the neuropathogenesis of brain lesions, including the neuronal and non-neuronal cells targeted during infection, along with the mechanisms underlying neurodegeneration. We analyzed 5-lipoxygenase (5-LOX) expression in the brain of 11 striped dolphins and 5 bottlenose dolphins, affected or not by encephalitic lesions of various degrees associated with DMV, T. gondii and B. ceti. All the 8 striped dolphins with encephalitis showed a more consistent 5-LOX expression than that observed in the 3 striped dolphins showing no morphologic evidence of brain lesions, with the most prominent band intensity being detected in a B. ceti-infected animal. Similar results were not obtained in T. gondii-infected vs T. gondii-uninfected bottlenose dolphins. Overall, the higher 5-LOX expression found in the brain of the 8 striped dolphins with infectious neuroinflammation is of interest, given that 5-LOX is a putative marker for neurodegeneration in human patients and in experimental animal models. Therefore, further investigation on this challenging issue is also needed in stranded cetaceans affected by central neuropathies.

Feline morbillivirus, a previously undescribed paramyxovirus associated with tubulointerstitial nephritis in domestic cats.

We describe the discovery and isolation of a paramyxovirus, feline morbillivirus (FmoPV), from domestic cat (Felis catus). FmoPV RNA was detected in 56 (12.3%) of 457 stray cats (53 urine, four rectal swabs, and one blood sample) by RT-PCR. Complete genome sequencing of three FmoPV strains showed genome sizes of 16,050 bases, the largest among morbilliviruses, because of unusually long 5' trailer sequences of 400 nt. FmoPV possesses identical gene contents (3'-N-P/V/C-M-F-H-L-5') and is phylogenetically clustered with other morbilliviruses. IgG against FmoPV N protein was positive in 49 sera (76.7%) of 56 RT-PCR-positive cats, but 78 (19.4%) of 401 RT-PCR-negative cats (P < 0.0001) by Western blot. FmoPV was isolated from CRFK feline kidney cells, causing cytopathic effects with cell rounding, detachment, lysis, and syncytia formation. FmoPV could also replicate in subsequent passages in primate Vero E6 cells. Infected cell lines exhibited finely granular and diffuse cytoplasmic fluorescence on immunostaining for FmoPV N protein. Electron microscopy showed enveloped virus with typical "herringbone" appearance of helical N in paramyxoviruses. Histological examination of necropsy tissues in two FmoPV-positive cats revealed interstitial inflammatory infiltrate and tubular degeneration/necrosis in kidneys, with decreased cauxin expression in degenerated tubular epithelial cells, compatible with tubulointerstitial nephritis (TIN). Immunohistochemical staining revealed FmoPV N protein-positive renal tubular cells and mononuclear cells in lymph nodes. A case-control study showed the presence of TIN in seven of 12 cats with FmoPV infection, but only two of 15 cats without FmoPV infection (P < 0.05), suggesting an association between FmoPV and TIN.

[Measles: the disease, epidemiology, history and vaccination programs in Chile]. / Sarampión: la enfermedad, epidemiología, historia y los programas de vacunación en Chile.

Measles, one of most important inmuno-preventable diseases, remains as a worldwide concern issue with an important morbidity and mortality. Particularly in the America region declared free of measles in 2010 by WHO, they still appear imported cases that origin outbreaks of variable magnitude in susceptible subjects usually none vaccinated which is the current situation in Santiago, the capital city of Chile. In this review we present characteristics of the etiological agent, the disease, epidemiological aspects with national historical focus, impact of immunization programs and outbreaks in Chile, in order to contribute to knowledge and management of this always present public health problem.

Is dolphin morbillivirus virulent for white-beaked dolphins (Lagenorhynchus albirostris)?

The virulence of morbilliviruses for toothed whales (odontocetes) appears to differ according to host species. In 4 species of odontocetes, morbilliviruses are highly virulent, causing large-scale epizootics with high mortality. In 8 other species of odontocetes, including white-beaked dolphins (Lagenorhynchus albirostris), morbilliviruses have been found as an incidental infection. In these species, the virulence of morbilliviruses is not clear. Therefore, the admission of 2 white-beaked dolphins with morbillivirus infection into a rehabilitation center provided a unique opportunity to investigate the virulence of morbillivirus in this species. By phylogenetic analysis, the morbilliviruses in both animals were identified as a dolphin morbillivirus (DMV) most closely related to that detected in a white-beaked dolphin in Germany in 2007. Both animals were examined clinically and pathologically. Case No. 1 had a chronic neural DMV infection, characterized by polioencephalitis in the cerebrum and morbillivirus antigen expression limited to neurons and glial cells. Surprisingly, no nervous signs were observed in this animal during the 6 months before death. Case No. 2 had a subacute systemic DMV infection, characterized by interstitial pneumonia, leucopenia, lymphoid depletion, and DMV antigen expression in mononuclear cells and syncytia in the lung and in mononuclear cells in multiple lymphoid organs. Cause of death was not attributed to DMV infection in either animal. DMV was not detected in 2 contemporaneously stranded white-beaked dolphins. Stranding rate did not increase in the region. These results suggest that DMV is not highly virulent for white-beaked dolphins.

In Vitro Modeling of Feline Morbillivirus Infections Using Primary Feline Kidney Cells.

Domestic cats are the natural host of feline morbilliviruses (FeMV). Although other species can also be infected (such as dogs and opossums), no laboratory animal infection model is established so far. In vitro models for studying the molecular pathogenesis are therefore needed. For this purpose, propagation and titration of FeMV are key techniques. Unlike other morbilliviruses, such as canine distemper virus (CDV) or measles virus (MV), FeMV is a slow growing virus in cell culture and is difficult to titrate using classical plaque techniques. Here we describe methods for the efficient isolation of FeMV from natural sources (e.g., urine), the propagation of viral stocks, and their titration. In addition, we establish the generation of a three-dimensional infection model mimicking the feline tubular epithelium.

Membrane fusion-mediated autophagy induction enhances morbillivirus cell-to-cell spread.

In the context of viral infections, autophagy induction can be beneficial or inhibitory. Within the Paramyxoviridae family, only morbilliviruses have been investigated and are reported to induce autophagy. Here we show that morbilliviruses rapidly induce autophagy and require this induction for efficient cell-to-cell spread. Coexpression of both glycoproteins in cells expressing one of the cellular receptors was required for autophagy induction, and LC3 punctum formation, indicative of autophagy, was mainly observed in syncytia. A similar correlation between syncytium formation and autophagy induction was also observed for other paramyxovirus glycoproteins, suggesting that membrane fusion-mediated autophagy may be common among paramyxoviruses and possibly other enveloped viruses.

[Morbilliviruses].

The genus Morbillivirus in the family Paramyxoviridae contains many pathogens, which are important for medicine or veterinary medicine. Because each morbillivirus has restricted host range and serologically monotypic, the virus infection and transmission is effectively controlled by vaccinations and surveillance. Rinderpest virus has been eradicated in 2011, and elimination of measles virus progresses worldwide. Recently, a new cell receptor for measles virus, nectin4 was identified. Both SLAM, a molecule expressing on immune cells, and nectin4, a molecule expressing on epithelial cells, are important to infectivity and pathogenicity of the virus.

Measles in Vaccinated People: Epidemiology and Challenges in Surveillance and Diagnosis in the Post-Elimination Phase. Spain, 2014-2020.

The MMR vaccination program was introduced in Spain in 1981. Consistently high vaccination coverage has led to Spain being declared free of endemic measles transmission since 2014. A few imported and import-related cases were reported during the post-elimination phase (2014 to 2020), with very low incidence: three cases per million of inhabitants a year, 70% in adults. In the post-elimination phase an increasing proportion of measles appeared in two-dose vaccinated individuals (up to 14%), posing a challenge to surveillance and laboratory investigations. Severity and clinical presentation were milder among the vaccinated. The IgM response varied and the viral load decreased, making the virus more difficult to detect. A valid set of samples (serum, urine and throat swab) is strongly recommended for accurate case classification. One third of measles in fully vaccinated people was contracted in healthcare settings, mainly in doctors and nurses, consistent with the important role of high intensity exposure in measles breakthrough cases. Surveillance protocols and laboratory algorithms should be adapted in advanced elimination settings. Reinforcing the immunity of people working in high exposure environments, such as healthcare settings, and implementing additional infection control measures, such as masking and social distancing, are becoming crucial for the global aim of measles eradication.

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 qPCRFeMV 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.

Measles virus receptors.

Measles virus (MV) has two envelope glycoproteins, the hemagglutinin (H) and fusion protein, which are responsible for attachment and membrane fusion, respectively. Signaling lymphocyte activation molecule (SLAM, also called CD150), a membrane glycoprotein expressed on immune cells, acts as the principal cellular receptor for MV, accounting for its lymphotropism and immunosuppressive nature. MV also infects polarized epithelial cells via an as yet unknown receptor molecule, thereby presumably facilitating transmission via aerosol droplets. Vaccine and laboratory-adapted strains of MV use ubiquitously expressed CD46 as an alternate receptor through amino acid substitutions in the H protein. The crystal structure of the H protein indicates that the putative binding sites for SLAM, CD46, and the epithelial cell receptor are strategically located in different positions of the H protein. Other molecules have also been implicated in MV infection, although their relevance remains to be determined. The identification of MV receptors has advanced our understanding of MV tropism and pathogenesis.

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.

Clustering of susceptible individuals within households can drive measles outbreaks: an individual-based model exploration.

When estimating important measures such as the herd immunity threshold, and the corresponding efforts required to eliminate measles, it is often assumed that susceptible individuals are uniformly distributed throughout populations. However, unvaccinated individuals may be clustered in a variety of ways, including by geographic location, by age, in schools, or in households. Here, we investigate to which extent different levels of within-household clustering of susceptible individuals may impact the risk and persistence of measles outbreaks. To this end, we apply an individual-based model, Stride, to a population of 600,000 individuals, using data from Flanders, Belgium. We construct a metric to estimate the level of within-household susceptibility clustering in the population. Furthermore, we compare realistic scenarios regarding the distribution of susceptible individuals within households in terms of their impact on epidemiological measures for outbreak risk and persistence. We find that higher levels of within-household clustering of susceptible individuals increase the risk, size and persistence of measles outbreaks. Ignoring within-household clustering thus leads to underestimations of required measles elimination and outbreak mitigation efforts.

Specific capture and whole-genome phylogeography of Dolphin morbillivirus.

Dolphin morbillivirus (DMV) is considered an emerging threat having caused several epidemics worldwide. Only few DMV genomes are publicly available. Here, we report the use of target enrichment directly from cetacean tissues to obtain novel DMV genome sequences, with sequence comparison and phylodynamic analysis. RNA from 15 tissue samples of cetaceans stranded along the Italian and French coasts (2008-2017) was purified and processed using custom probes (by bait hybridization) for target enrichment and sequenced on Illumina MiSeq. Data were mapped against the reference genome, and the novel sequences were aligned to the available genome sequences. The alignment was then used for phylogenetic and phylogeographic analysis using MrBayes and BEAST. We herein report that target enrichment by specific capture may be a successful strategy for whole-genome sequencing of DMV directly from field samples. By this strategy, 14 complete and one partially complete genomes were obtained, with reads mapping to the virus up to 98% and coverage up to 7800X. The phylogenetic tree well discriminated the Mediterranean and the NE-Atlantic strains, circulating in the Mediterranean Sea and causing two different epidemics (2008-2015 and 2014-2017, respectively), with a limited time overlap of the two strains, sharing a common ancestor approximately in 1998.

Morbilliviruses: Entry, Exit and Everything In-Between.

Morbilliviruses are important pathogens, to the point that they have shaped the history of human and animal health [...].