Establishment of a new equine embryo brain primary cell culture with long-term expansion.

Primary cell cultures derived from human embryo lung play a crucial role in virology by aiding virus propagation and vaccine development. These cultures exhibit a notable ability to undergo multiple subcultures, often reaching up to 70 passages. However, finding alternative primary cell cultures with similar longevity and usefulness is challenging. In this study, we introduce a novel primary culture cells derived from equine embryo brain (FEB), which cells exhibited remarkable long-term cultivation potential. The FEB was established and maintained using Sumitomo Nerve-Cell Culture System Comparison studies were conducted with fetal equine kidney cell line (FEK-Tc13) to assess growth rates and subculture longevity. Immunological characterization was performed using neuronal markers to confirm the neural nature of FEB cells. Viral growth assessments were conducted using equine herpesviruses (EHV-1 and EHV-4) to evaluate infectivity and cytopathic effects in FEB cells. PCR analysis and real-time PCR assays were employed to detect viral genomic DNA and transcription activity of EHVs in infected FEB cells. FEB cells demonstrated faster growth rates compared to fetal equine kidney cell line (FEK-Tc13 cells) and exhibited sustained subculture capability exceeding 50 passages. Immunostaining confirmed the glial identity of FEB cells. Both equine herpesviruses 1 and 4 EHV-1 and EHV-4 viruses efficiently replicated in FEB cells, resulting in clear cytopathic effects. PCR analysis detected genomic DNA of EHVs in infected FEB cells, indicating successful viral infection. The establishment of FEB cells with extended subculture capability highlights their potential utility as a model system for studying neural cell biology and viral infections.

Isolation, molecular characterization, and genetic diversity of recently isolated foot-and-mouth disease virus serotype A in Egypt.

Foot-and-mouth Disease (FMD) is a highly contagious viral disease affecting all hoof-cloven animals. Serotypes A, O and SAT 2 of the foot-and-mouth disease virus (FMDV) are circulating in Egypt. The present study aimed to identify and molecularly characterize the FMDV strains circulating in Northern Egypt during an epidemic that struck the nation in 2022. RNA was extracted from the epithelial specimens, vesicular fluid from affected cattle. The samples were screened using real-time reverse-transcription polymerase chain reaction (RT-PCR) targeting the RNA-dependent RNA polymerase (RdRp) gene. Positive samples underwent individual serotype-specific amplification using primers designed for VP1 of O, A, and SAT 2 serotypes. Subsequently, direct sequencing was performed on the positive samples. The real-time RT-PCR detected positive samples from epithelial and vesicular fluid samples, but not in the blood of infected animals. Out of the 16 samples, seven tested positive for FMDV serotype A. Of these seven positive samples, six were categorized as serotype A-African topotype-G-IV, and these positive samples were isolated in BHK-21 cells, yielding an overt cytopathic effect caused by the virus. In conclusion, it is necessary to sustain continuous surveillance of the evolution of circulating FMDV strains to facilitate the assessment and aid in the selection of vaccine strains for the effective control of FMDV in Egypt.

Occupational Health Hazards Among Veterinarians in Saudi Arabia.

Introduction Veterinarians and other professionals who interact with animals on a daily basis encounter an elevated risk of exposure to both known and as-yet-undiscovered microbial agents. Additionally, they are also exposed to physical, chemical, and environmental hazards. Enhancing occupational health and safety in this context carries significant global significance. Methods This study aimed to comprehensively identify and outline the various biological, physical, chemical, and environmental health threats that were encountered by veterinarians in Saudi Arabia. To achieve this, we designed a self-completed questionnaire for 529 participants. The survey encompassed potential occupational hazards such as microbial diseases, injuries resulting from animal bites and scratches, allergies, and environmental risks like sunstroke and dust storms. Results Among the 529 participating veterinarians, 45.9% (243 individuals) reported instances of zoonotic diseases within the past five years. Notably, potential viral agents included Middle East respiratory syndrome coronavirus, avian influenza, and foot-and-mouth disease virus. Bacterial diseases were also frequently documented, with brucellosis (18.7%) and salmonellosis (7.9%) being notable pathogens. Protozoal infections were led by Leishmaniosis, constituting the most commonly detected protozoa (29 /529, 5.5%). Interestingly, 345 (65.2%) of the individuals reported that they have experienced animal bites and scratches. Needle stick injuries were also a common occupational hazard, with an incidence rate of 19.1%. Additionally, chemical exposure was prevalent, particularly to disinfectants (57.5%) and veterinary drugs (23.4%). The study participants also reported their exposure to various environmental hazards, including sunstroke, dust, sandstorms, and heavy rains. Conclusion The findings of this study draw attention to a concerning trend among veterinarians in Saudi Arabia. Their personal health and safety appear to receive inadequate attention, potentially heightening the risk of occupationally related health hazards. These outcomes highlight the need for a reevaluation of safety protocols and infection control practices within the veterinary profession. The implications of this study can potentially inform the development of policies and initiatives aimed at mitigating occupationally related health hazards among veterinarians in Saudi Arabia.

Full-Length Genome of the Equine Influenza A Virus Subtype H3N8 from 2019 Outbreak in Saudi Arabia.

Equine influenza is a major cause of respiratory infections in horses and can spread rapidly despite the availability of commercial vaccines. This study aimed to screen the incidence of equine influenza virus (EIV) and molecularly characterize the haemagglutinin and neuraminidase from positive EIV field samples collected from Saudi Arabia. Six-hundred twenty-one horses from 57 horse barns were screened for the presence of the clinical signs, suggestive for equine influenza, from different parts of Saudi Arabia. Nasopharyngeal swabs were collected from each horse showing respiratory distress. Samples from the same horse barn were pooled together and screened for the presence of the influenza A virus using quantitative real time reverse transcriptase polymerase chain reaction (qRT-PCR). Selective positive samples were subjected to full-length genome sequencing using MiSeq Illumina. Out of the total 57 pools, 39 were found positive to EIV using qRT-PCR. Full-length gene sequences were compared with representative EIV strains selected from the GenBank database. Phylogenetic analysis of the HA and NA genes revealed that the identified virus strains belong to H3N8 clade 1 of the Florida sublineage and were very similar to viruses identified in USA in 2019, with no current evidence for reassortment. This is one of the first reports providing detailed description and characterization of EIVs in Saudi Arabia. Detailed surveillance and genetic information sharing could allow genetic evolution of equine influenza viruses to be monitored more effectively on a global basis and aid in refinement of vaccine strain selection for EIV.

Scanning Electron Microscopic Findings on Respiratory Organs of Some Naturally Infected Dromedary Camels with the Lineage-B of the Middle East Respiratory Syndrome Coronavirus (MERS-CoV) in Saudi Arabia-2018.

The currently known animal reservoir for MERS-CoV is the dromedary camel. The clinical pattern of the MERS-CoV field infection in dromedary camels is not yet fully studied well. Some pathological changes and the detection of the MERS-CoV antigens by immunohistochemistry have been recently reported. However, the nature of these changes by the scanning electron microscope (SEM) was not revealed. The objective of this study was to document some changes in the respiratory organs induced by the natural MERS-CoV infection using the SEM. We previously identified three positive animals naturally infected with MERS-CoV and two other negative animals. Previous pathological studies on the positive animals showed varying degrees of alterations. MERS-CoV-S and MERS-CoV-Nc proteins were detected in the organs of positive animals. In the current study, we used the same tissues and sections for the SEM examination. We established a histopathology lesion scoring system by the SEM for the nasal turbinate and trachea. Our results showed various degrees of involvement per animal. The main observed characteristic findings are massive ciliary loss, ciliary disorientation, and goblet cell hyperplasia, especially in the respiratory organs, particularly the nasal turbinate and trachea in some animals. The lungs of some affected animals showed signs of marked interstitial pneumonia with damage to the alveolar walls. The partial MERS-CoV-S gene sequencing from the nasal swabs of some dromedary camels admitted to this slaughterhouse confirms the circulating strains belong to clade-B of MERS-CoV. These results confirm the respiratory tropism of the virus and the detection of the virus in the nasal cavity. Further studies are needed to explore the pathological alterations induced by MERS-CoV infection in various body organs of the MERS-CoV naturally infected dromedary camels.

Time Course-Dependent Study on Equine Herpes Virus 9-Induced Abortion in Syrian Hamsters.

This study aimed to follow the time-course pathogenesis of EHV-9 abortion in early and late trimesters. Twenty-seven pregnant hamster dams were divided into three groups: (G1) control, (G2) EHV-9-inoculated on the 5th day (early trimester), and (G3) EHV-9-inoculated on the 10th day of gestation (late trimester). Dams were sacrificed at different time points during gestation and examined for viremia and viral DNA in different fetal and maternal tissues and pathological changes in fetal tissue, placenta, and cytokines. Animals in G3 showed a marked increase in the number of dead fetuses than those in G2. Histopathological findings of G2 showed early band coagulative necrosis of maternal spaces and stromal decidual cells. Necrotic changes were observed within the decidua basalis, spongiotrophoblast layer, and labyrinth. First, the virus was localized within mononuclear leukocytes in the decidua capsularis and basalis, and within the necrotic chorionic villi and cervical epithelium. G3 demonstrated degenerative changes within the chorionic villi and trophospongium. The virus antigen was observed within the chorionic villi, trophoblasts, mononuclear cells, and fetal tissues. In conclusion, EHV-9 induced abortion mostly occurs through necrosis of the chorionic villi and cannot cross through the capsular placenta in the early trimester but can through the developed decidual placentation.

Some pathological observations on the naturally infected dromedary camels (Camelus dromedarius) with the Middle East respiratory syndrome coronavirus (MERS-CoV) in Saudi Arabia 2018-2019.

Background: The natural MERS-CoV infection in dromedary camels is understudied. Recent experimental studies showed no obvious clinical signs in the infected dromedary camels.Aim: To study the pathological changes associated with natural MERS-CoV infection in dromedary camels.Methods: Tissues from three MERS-CoV positive animals as well as two negative animals were collected and examined for the presence of pathological changes. The screening of the animals was carried out first by the rapid agglutination test and then confirmed by the RT-PCR. The selected animals ranged from six to twelve months in age. The sensitivity of the latter technique was much higher in the detection of MERS-CoV than the Rapid test (14 out of 75 animals positive or 18% versus 31 out of 75 positive or 41%).Results: MERS-CoV induced marked desquamation of the respiratory epithelium accompanied by lamina propria and submucosal mononuclear cells infiltration, epithelial hyperplasia in the respiratory tract, and interstitial pneumonia. Ciliary cell loss was seen in the trachea and turbinate. In addition, degeneration of glomerular capillaries with the complete destruction of glomerular tufts that were replaced with fibrinous exudate in renal corpuscles in the renal cortex were noticed. Expression of the MERS-CoV-S1 and MERS-CoV-N proteins was revealed in respiratory tract, and kidneys.Conclusion: To our knowledge, this is the first study describing the pathological changes of MERS-CoV infection in dromedary camels under natural conditions. In contrast to experimental infection in case of spontaneous infection interstitial pneumonea is evident at least in some affected animals.

Challenge infection model for MERS-CoV based on naturally infected camels.

BACKGROUND: Middle East Respiratory Syndrome coronavirus (MERS-CoV) is an emerging virus that infects humans and camels with no approved antiviral therapy or vaccine. Some vaccines are in development for camels as a one-health intervention where vaccinating camels is proposed to reduce human viral exposure. This intervention will require an understanding of the prior exposure of camels to the virus and appropriate vaccine efficacy studies in camels. METHODS: We conducted a cross sectional seroprevalence study in young dromedary camels to determine the rate of MERS-CoV seropositivity in young camels. Next, we utilised naturally infected camels as a natural challenge model that can be used by co-housing these camels with healthy naive camels in a ratio of 1 to 2. This model is aimed to support studies on natural virus transmission as well as evaluating drug and vaccine efficacy. RESULTS: We found that 90% of the screened camels have pre-existing antibodies for MERS-CoV. In addition, the challenge model resulted in MERS-CoV transmission within 48 h with infections that continued for 14 days post challenge. CONCLUSIONS: Our finding suggests that the majority of young dromedary camels in Saudi Arabia are seropositive and that naturally infected camels can serve as a challenge model to assess transmission, therapeutics, and vaccine efficacy.

The dipeptidyl peptidase-4 expression in some MERS-CoV naturally infected dromedary camels in Saudi Arabia 2018-2019.

MERS-CoV usually causes respiratory and renal failure in some patients, which may be the underlying cause of death. Dromedary camels are the only known reservoir of the virus until now. They shed the virus in their body secretions thus potentiate a risk for human infection. MERS-CoV tropism and replication is mainly affected by the presence of certain receptor ligands on the target tissues. The dipeptidyl peptidase-4 (DPP-4) is believed to act as receptors for MERS-CoV. The main objective of this study was to determine the expression levels of the DPP-4 in various organs of some naturally infected camels. We conducted a surveillance study to identify some positive MERS-CoV infected camels. Three positive animals identified by the Real time PCR. Our results are clearly showing the high level of expression of the DPP-4 in various organs of these animals' particularly nasal turbinate, trachea, and lungs. The expression level may explain at least in part the pathogenesis of MERS-CoV in these organs. These findings confirm the pivotal roles of the DPP4 in the context of the MER-CoV infection in dromedary camels. Further studies are needed for a better understanding of the molecular pathogenesis of MER-CoV infection.

Humoral Immunogenicity and Efficacy of a Single Dose of ChAdOx1 MERS Vaccine Candidate in Dromedary Camels.

MERS-CoV seronegative and seropositive camels received a single intramuscular dose of ChAdOx1 MERS, a replication-deficient adenoviral vectored vaccine expressing MERS-CoV spike protein, with further groups receiving control vaccinations. Infectious camels with active naturally acquired MERS-CoV infection, were co-housed with the vaccinated camels at a ratio of 1:2 (infected:vaccinated); nasal discharge and virus titres were monitored for 14 days. Overall, the vaccination reduced virus shedding and nasal discharge (p = 0.0059 and p = 0.0274, respectively). Antibody responses in seropositive camels were enhancedby the vaccine; these camels had a higher average age than seronegative. Older seronegative camels responded more strongly to vaccination than younger animals; and neutralising antibodies were detected in nasal swabs. Further work is required to optimise vaccine regimens for younger seronegative camels.

Rabies among animals in Saudi Arabia.

BACKGROUND: Rabies is a fatal viral disease that continues to threaten human and animal health in endemic countries. Rabies is endemic in animals in the Arabian Peninsula. Although Saudi Arabia is the largest country on the Peninsula, little has been reported in the country about rabies situation. METHODS: A total of 199 animals suspected of rabies from 2010 to 2017, were examined for rabies infection using the Direct Fluorescent Antibody Test (DFAT). RESULTS: There were 158 (79.4%) positive cases of rabies of the examined animals, Most positive cases were found in Al-Qassim (63), Eastern region (48), Riyadh (25) and Al-Madina (10). Rabies was diagnosed in Procavia capensis and monkeys (Papio hamadryas hamadryas) in Saudi Arabia for the first time. In addition, infected livestock, especially camels, sheep and goat that pose a risk to veterinarians and farmers which increases the risk of potential zoonosis of rabies in Saudi Arabia. CONCLUSION: These findings indicate that Rabies in Saudi Arabia remain a public health problem and dogs and camels are the main reservoir and continue to present health risks for both human and animals throughout the country, underscoring the importance of applying rabies control measures to animals and humans.

Poxvirus infection in a Steller's sea eagle (Haliaeetus pelagicus).

A severely emaciated adult Steller's sea eagle (Haliaeetus pelagicus) was found dead with electrocution-induced severe wing laceration, and with multiple cutaneous pock nodules at the periocular regions of both sides nearby the medial canthi and rhamphotheca. Histopathological examination of the nodules revealed hyperplasia of the epidermis with vacuolar degeneration and intracytoplasmic inclusion bodies (Bollinger bodies). The proventriculus was severely affected by nematodes and was ulcerated. Nucleotide sequencing of a PCR-amplified product of Avipoxvirus 4b core gene revealed 100% identity to the sequence of Avipoxvirus derived from other eagle species. This report describes the first detection of Avipoxvirus clade A from a Steller's sea eagle.

Development and characterization of ORF68 negative equine herpes virus type-1, Ab4p strain.

Equine herpesvirus-1 (EHV-1) is an important pathogen, which infects horses worldwide with high morbidity but low mortality rates. The respiratory disorders and abortions are the most common indicators. Ab4p (an abortigenic and paralytic virus) is one of the most important and virulent strains. The development and functional characterization of the open reading frame-68 (ORF68) negative EHV-1 Ab4p mutants and an assessment of their roles in the infection at the cellular level were the main targets of the current study. Escherichia coli DH10ß containing the Ab4p bacterial artificial chromosome (pAb4pBAC) and Red/ET expression vector were used to develop different ORF68 mutants. Multi-step growth kinetic experiments were conducted in order to evaluate the growth properties of the constructed mutant viruses. Growth of the Ab4pΔORF68 showed the lowest titer, compared to the Ab4pΔORF68R, Ab4pΔORF68R non-sense, and the parent Ab4p viruses without any significant difference (P > 0.05). The growth of the mutant viruses was almost similar across the cell types, but viruses growth was more efficient in FHK cells as judged by the number of the obtained virus particles. The plaque size of Ab4pΔORF68 was significantly (40%) smaller than those of Ab4p (P < 0.01), Ab4pΔORF68R, and Ab4pΔORF68R non-sense viruses which confirmed the importance of ORF68 protein in the cell-to-cell transmission of EHV-1. Subcellular localization of the green fluorescent protein (GFP) ORF68 gene fusion product showed late expression with intranuclear localization of the transfected cells while immunofluorescent antibody technique (IFAT) localized it at the nucleus and nuclear membranes of the infected cells. Hence, it could be concluded that ORF68 protein may not be essential for EHV-1 Ab4p growth but plays a crucial role in virus penetration and transmission at the cellular level. Therefore, the generated EHV-1 ORF68 negative mutant could be a prospective candidate for the development of a vaccine marker.

Circulation of Influenza A(H5N8) Virus, Saudi Arabia.

Highly pathogenic avian influenza A(H5N8) viruses have been detected in several continents. However, limited viral sequence data are available from countries in the Middle East. We report full-genome analyses of highly pathogenic H5N8 viruses recently detected in different provinces in Saudi Arabia.

The prevalence of Middle East respiratory Syndrome coronavirus (MERS-CoV) infection in livestock and temporal relation to locations and seasons.

BACKGROUND: The Middle East respiratory syndrome (MERS) has been reported for the first time infecting a human being since 2012. The WHO was notified of 27 countries have reported cases of MERS, the majority of these cases occur in the Arabian Peninsula, particularly in Saudi Arabia. Dromedary camels are likely to be the main source of Middle East respiratory syndrome virus (MERS-CoV) infection in humans. METHODS: MERS-CoV infection rates among camels in livestock markets and slaughterhouses were investigated in Saudi Arabia. A total of 698 nasal swabs were collected and examined with Rapid assay and rtRT-PCR. Ten MERS-CoV positive samples were subjected to full genomic sequencing. In addition, the sensitivity and specificity of the Rapid immunochromatographic assay (BioNote, South Korea) was evaluated as a diagnostic tool for MERS-CoV compared to rtRT-PCR. RESULTS: The results showed a high percentage of dromedaries (56.4%) had evidence for nasal MERS-CoV infection. Phylogenetic analysis of the ten MERS-CoV isolates showed that the sequences were closely related to the other MERS-CoV strains recovered from camels and human cases. Moreover, the results showed that 195 samples were positive for MERS-CoV by rapid assay compared to 394 positive samples of rtRT-PCR, which showed low rapid assay sensitivity (49.49%) while, the specificity were found to be 100%. CONCLUSION: These findings indicate that these sites are a highly-hazardous to zoonotic diseases.

Cross-sectional study of MERS-CoV-specific RNA and antibodies in animals that have had contact with MERS patients in Saudi Arabia.

BACKGROUND: Middle East respiratory syndrome coronavirus (MERS-CoV) is a newly emerged coronavirus that is associated with a severe respiratory disease in humans in the Middle East. The epidemiological profiles of the MERS-CoV infections suggest zoonotic transmission from an animal reservoir to humans. METHODS: This study was designed to investigate animal herds associated with Middle East respiratory syndrome (MERS)-infected patients in Saudi Arabia, during the last three years (2014-2016). Nasal swabs and serum samples from 584 dromedary camels, 39 sheep, 51 goats, and 2 cattle were collected. Nasal samples from camels, sheep, goats, and cattle were examined by real-time reverse-transcription PCR (RT-PCR) to detect MERS-CoV RNA, and the Anti-MERS ELISA assay was performed to detect camel humeral immune response (IgG) to MERS-CoV S1 antigen infection. The complete genome sequencing of ten MERS-CoV camel isolates and phylogenetic analysis was performed. RESULTS: The data indicated that seventy-five dromedary camels were positive for MERS-CoV RNA; the virus was not detected in sheep, goats, and cattle. MERS-CoV RNA from infected camels was not detected beyond 2 weeks after the first positive result was detected in nasal swabs obtained from infected camels. Anti-MERS ELISA assays showed that 70.9% of camels related to human cases had antibodies to MERS-CoV. The full genome sequences of the ten MERS-CoV camel isolates were identical to their corresponding patients and were grouped together within the larger MERS-CoV sequences cluster for human and camel isolates reported form the Arabian Peninsula. CONCLUSIONS: These findings indicate that camels are a significant reservoir for the maintenance of MERS-CoVs, and they are an important source of human infection with MERS.

Morphologic and molecular characteristics of Sarcocystis atraii n. sp. (Apicomplexa: Sarcocystidae) infecting the common coot (Fulica atra) from Egypt.

A single morphologic type of Sarcocystis cysts found in two out of 43 examined common coots, Fulica atra, is considered to represent a new species for which the name Sarcocystis atraii n. sp. is proposed and its description is provided. Coots were hunted from the vicinity of Brolos Lake located at KafrElsheikh province, Egypt. The structural morphology of the revealed sarcocysts was described using light and transmission electron microscopy. Sarcocysts were found in the leg and thigh muscles. The cysts were microscopic and measured 165-850 µm in length × 50-85 µm in width. Histologically; the sarcocyst wall was wavy and had minute undulations. Ultrastructurally, it measured 1-3 µm in thickness and possessed many mushroom-like villar protrusions sometimes originating from other mushroom-like villar protrusions that measured approximately 0.5-2 µm in length and up to 2 µm in width, with the presence of electron dense ground substance of 300 nm to 1 µm thick. The bradyzoites were elongated, banana-shaped and measured 7.5-14 × 1.5-2.5 µm, with centrally or terminally located nuclei. The ultrastructural features of the cyst wall belonged to type 24. On the basis of sequencing and phylogenic analyses for 18S rRNA , 28S rRNA genes and ITS-1 region; S. atraii n. sp. is considered a genetically distinct species, being most closely related to avian Sarcocystis spp. whose definitive hosts are predatory mammals.

Comprehensive Serology Based on a Peptide ELISA to Assess the Prevalence of Closely Related Equine Herpesviruses in Zoo and Wild Animals.

Equine herpesvirus type 1 (EHV-1) causes respiratory disorders and abortion in equids while EHV-1 regularly causes equine herpesvirus myeloencephalopathy (EHM), a stroke-like syndrome following endothelial cell infection in horses. Both EHV-1 and EHV-9 infections of non-definitive hosts often result in neuronal infection and high case fatality rates. Hence, EHV-1 and EHV-9 are somewhat unusual herpesviruses and lack strict host specificity, and the true extent of their host ranges have remained unclear. In order to determine the seroprevalence of EHV-1 and EHV-9, a sensitive and specific peptide-based ELISA was developed and applied to 428 sera from captive and wild animals representing 30 species in 12 families and five orders. Members of the Equidae, Rhinocerotidae and Bovidae were serologically positive for EHV-1 and EHV-9. The prevalence of EHV-1 in the sampled wild zebra populations was significantly higher than in zoos suggesting captivity may reduce exposure to EHV-1. Furthermore, the seroprevalence for EHV-1 was significantly higher than for EHV-9 in zebras. In contrast, EHV-9 antibody prevalence was high in captive and wild African rhinoceros species suggesting that they may serve as a reservoir or natural host for EHV-9. Thus, EHV-1 and EHV-9 have a broad host range favoring African herbivores and may have acquired novel natural hosts in ecosystems where wild equids are common and are in close contact with other perissodactyls.

Functional characterization of EUL47 in productive replication, morphogenesis and infectivity of equine herpesvirus 1.

EUL47 is a major component of the tegument of equine herpesvirus 1 (EHV-1). To determine its function, we used Red/ET cloning to delete its gene (gene 13) from EHV-1 strain Ab4p inserted into a bacterial artificial chromosome (BAC), yielding Ab4pattBΔ13. We also examined the reverted virus (Ab4pattB13R). Ab4pattBΔ13 replicated in rabbit kidney (RK)-13 cells, indicating that ORF13 is dispensable for virus replication in cell culture. Its intracellular and extracellular titers were about 10- and 100-fold lower than those of the revertant and parent strains, respectively. In addition, the plaque size was half the plaque sizes of the other two strains. The particle-to-plaque forming unit ratio of Ab4pattBΔ13 was 21-fold greater than the ratios of the revertant and parent strains. No enveloped virions were detected in the cytoplasm of Ab4pattBΔ13-infected cells by transmission electron microscopy. In hamster, Ab4pattBΔ13 caused clinical signs and weight loss after only 1 day, but induced less severe neurological signs than did the revertant and parent strains. These results indicate that EUL47 is structurally required for normal virus replication, viral morphogenesis and viral infectivity, and that loss of EUL47 moderately attenuates the neuropathogenicity of EHV-1 in the hamster model.

Cynomolgus monkeys (Macaca fascicularis) may not become infected with equine herpesvirus 9.

BACKGROUND: It was suggested that Equine herpesvirus 9 (EHV-9) could be transmitted to higher non-human primates. METHODS: Four cynomolgus monkeys (Macaca fascicularis) were inoculated with EHV-9 by the nasal route. RESULTS: No abnormalities were observed pathologically, immunohistochemically, and genetically. CONCLUSIONS: These findings indicate that cynomolgus monkeys are not susceptible to EHV-9.