Comparison of HVT-ND recombinant and convection-based Newcastle disease vaccination programs in the protection against the genotype VII NDV challenges: an experimental study.

Newcastle disease virus (NDV) belongs to the Avulavirus genus and Paramyxoviridae family virus that causes acute, highly infectious Newcastle disease in poultry. The two proteins of haemagglutinin neuraminidase (HN) and fusion (F) are key virulence factors with an important role in its immunogenicity. Genotype VII NDV is still among the most serious viral hazards to the poultry industry worldwide. In this study, a commercial vector vaccine (HVT-NDV) was evaluated compared to the conventional vaccination strategy against Iranian genotype VII. This experiment showed that the group receiving the conventional vaccination strategy had higher antibodies, fewer clinical signs, and lower viral loads in tracheal swabs and feces. Also, two vaccine groups showed significant difference, which could have resulted from two extra vaccine doses in the conventional group. However, except for antibody levels in commercial chickens in the Iran new-generation vaccine, this difference was minor. Further, both groups showed 100% protection in the challenge study. Despite the phylogenetic gap between the NDV-F gene placed in the vector vaccine and the challenge virus (genotypes I and VII, respectively), the rHVT-NDV vaccine offered strong clinical protection and decreased challenge virus shedding considerably.

The full genome characterization of avian encephalomyelitis virus, Iran: a vertical transmission case.

Avian encephalomyelitis (AE) is an important infectious poultry disease worldwide that is caused by avian encephalomyelitis virus (AEV). The causative virus can be transmitted both horizontally and vertically. In the present study, an AEV suspected outbreak with typical neurological signs occurred in broilers. Histopathological examination, RT-PCR assay and full genome sequencing were applied to confirm the presence of AEV. Phylogenetic analysis of the full genome sequence showed that the detected AEV strain at 7055 nucleotide length is classified in cluster I and is closely related to vaccinal USA and China originated isolates. Although, the outbreaks of AE in progeny of vaccinated breeders have been reported previously, the source of infection was unknown. Based on the results obtained in this study, the outbreaks are vaccine-originated. This study provides the first whole genome analysis of AEV from Iran and reveals that the AEV possesses a hepatitis C virus-like internal ribosome entry site.

Whole-genome characterization of avian picornaviruses from diarrheic broiler chickens co-infected with multiple picornaviruses in Iran.

Gastrointestinal symptoms in poultry are caused by several factors, such as infecting viruses. Several avian picornaviruses can cause diarrhea in these valuable animals. Poultry flocks in Iran suffer from gastrointestinal diseases, and information on picornaviruses is limited. In this study, two genera of avian picornaviruses were isolated from poultry and identified by the viral metagenomics. Fecal samples were collected from broiler chicken flocks affected with diarrhea from Gilan province Iran. The results showed that Eastern chicken flocks carried two genera of picornaviridae belonging to Sicinivirus A (SiV A) and Megrivirus C (MeV C). The Western chicken flocks carried SiV A based on whole-genome sequencing data. SiV A had type II IRES and MeV C contained a type IVB IRES 5'UTR. Phylogenetic results showed that all these three picornaviruses were similar to the Hungarian isolates. Interestingly, two different picornavirus genera were simultaneously co-infected with Eastern flocks. This phenomenon could increase and facilitate the recombination and evolution rate of picornaviruses and consequently cause this diversity of gastrointestinal diseases in poultry. This is the first report and complete genome sequencing of Sicinivirus and Megrivirus in Iran. Further studies are needed to evaluate the pathogenic potential of these picornaviruses.

Evaluation of viral load and transcriptome changes in tracheal tissue of two hybrids of commercial broiler chickens infected with avian infectious bronchitis virus: a comparative study.

Infectious bronchitis virus (IBV) is one of the major threats to the poultry industry, with significant economic consequences. Despite strict measures, the disease is difficult to control worldwide. Experimental evidence demonstrates that the severity of IBV is affected by the genetic background of the chicken, and the selection of appropriate breeds can increase production efficiency. Therefore, the aim of the present study was to assess the strength of the immune response to IBV in tracheal tissues of Ross 308 and Cobb 500 broiler chickens by evaluating transcriptome changes, focusing on immune responses and the viral load in tracheal tissues two days after IBV infection. We identified 899 and 1350 differentially expressed genes (DEGs) in the Cobb 500 and Ross 308 experimental groups compared to their respective control groups. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis indicated the involvement of signaling pathways (Toll-like receptor [TLR], NOD-like receptor [NLR], and RIG-I-like receptor [RLR] signaling pathways). Interestingly, the RLR signaling pathway appears to be affected only in the Cobb hybrid. Furthermore, the viral loads in tracheal samples obtained from the Ross challenged group were significantly higher than those of the Cobb challenged group. The results of this study indicated that the host transcriptional response to IBV infection as well as the viral load can differ by hybrid. Furthermore, genes such as TLR-3, ChIFN-α, MDA5, LGP2, IRF-7, NF-κB, and TRIM25 may interfere with IBV proliferation.

Comparative trachea transcriptome analysis in SPF broiler chickens infected with avian infectious bronchitis and avian influenza viruses.

Infectious bronchitis virus (IBV) and avian influenza virus (AIV) are two major respiratory infections in chickens. The coinfection of these viruses can cause significant financial losses and severe complications in the poultry industry across the world. To examine transcriptome profile changes during the early stages of infection, differential transcriptional profiles in tracheal tissue of three infected groups (i.e., IBV, AIV, and coinfected) were compared with the control group. Specific-pathogen-free chickens were challenged with Iranian variant-2-like IBV (IS/1494), UT-Barin isolates of H9N2 (A/chicken/Mashhad/UT-Barin/2017), and IBV-AIV coinfection; then, RNA was extracted from tracheal tissue. The Illumina RNA-sequencing (RNA-seq) technique was employed to investigate changes in the Transcriptome. Up- and downregulated differentially expressed genes (DEGs) were detected in the trachea transcriptome of all groups. The Kyoto Encyclopedia of Genes and Genomes pathway and Gene Ontology databases were examined to identify possible relationships between DEGs. In the experimental groups, upregulated genes were higher compared to downregulated genes. A more severe immune response was observed in the coinfected group; further, cytokine-cytokine receptor interaction, RIG-I-like receptor signaling, Toll-like receptor signaling, NOD-like receptor signaling, Janus kinase/signal transducer, and activator of transcription, and apoptotic pathways were important upregulated genes in this group. The findings of this paper may give a better understanding of transcriptome changes in the trachea during the early stages of infection with these viruses.

Effects of a combination of Mass and Dutch variant as an inactivated vaccine against variant 2 avian infectious bronchitis virus challenge.

The present study aimed to evaluate the effects of inactivated vaccines combining Mass and Dutch variants as vaccine boosters after H120 priming on inhibiting variant 2 viral load in the kidneys (as the target organ) and reducing fecal shedding. Ciliostasis score and antibody response were investigated as well. A total of 150 specific-pathogen-free (SPF) chicken were divided into six groups. All groups were vaccinated with a single dose of attenuated H120 vaccine except for two (no vaccine groups). Then, three groups received booster vaccines with inactivated polyvalent vaccines. At the 42 day of age, all groups were challenged with variant 2 viruses except for one (no vaccine group). Next, antibody response and infectious bronchitis virus viral load in kidneys and fecal shedding were evaluated by the enzyme-linked immunosorbent assay and quantitative real-time polymerase chain reaction. Then the ciliostasis score was investigated. In general, a vaccination program including a mass serotype attenuated vaccine (H120) as priming and polyvalent vaccines can significantly protect chickens against variant 2 infection through reducing viral load in kidneys and fecal shedding. Furthermore, the vaccination program can decrease ciliostasis in the epithelial ciliary tissue.

Coronavirus: proteomics analysis of chicken kidney tissue infected with variant 2 (IS-1494)-like avian infectious bronchitis virus.

Avian infectious bronchitis virus is one of the most important gammacoronaviruses, which causes a highly contagious disease. In this study, we investigated changes in the proteome of kidney tissue of specific-pathogen-free (SPF) chickens that were infected with an isolate of the nephrotropic variant 2 genotype (IS/1494/06) of avian coronavirus. Twenty 1-day-old SPF White Leghorn chickens were randomly divided into two groups, each comprising 10 chickens, which were kept in separate positive-pressure isolators. Chickens in group A served as a virus-free control group up to the end of the experiment, whereas chickens in group B were inoculated with 0.1 ml of 104.5 EID50 of the IBV/chicken/Iran/UTIVO-C/2014 isolate of IBV, and kidney tissue samples were collected at 2 and 7 days post-inoculation (dpi) from both groups. Sequencing of five protein spots at 2 dpi and 22 spots at 7 dpi that showed differential expression by two-dimensional electrophoresis (2DE) along with fold change greater than 2 was done by MS-MALDI/TOF/TOF. Furthermore, the corresponding protein-protein interaction (PPI) networks at 2 and 7 dpi were identified to develop a detailed understanding of the mechanism of molecular pathogenesis. Topological graph analysis of this undirected PPI network revealed the effect of 10 genes in the 2 dpi PPI network and nine genes in the 7 dpi PPI network during virus pathogenesis. Proteins that were found by 2DE analysis and MS/TOF-TOF mass spectrometry to be down- or upregulated were subjected to PPI network analysis to identify interactions with other cellular components. The results show that cellular metabolism was altered due to viral infection. Additionally, multifunctional heat shock proteins with a significant role in host cell survival may be employed circuitously by the virus to reach its target. The data from this study suggest that the process of pathogenesis that occurs during avian coronavirus infection involves the regulation of vital cellular processes and the gradual disruption of critical cellular functions.

Predominance of Fourth Panzootic Newcastle Disease Virus Subgenotype VII.1.1 in Iran and Its Relation to the Genotypes Circulating in the Region.

Following recent Newcastle disease virus (NDV) outbreaks in Iranian poultry farms which were mostly associated with lesions of the avian gastrointestinal tract, it was speculated that the scale of the outbreaks could be attributed in part to co-circulating infectious agents or a new NDV genotype/subgenotype. This speculation was due to the isolation of a few 5th panzootic subgenotype VII.2 viruses from Iranian poultry farms in 2017. Samples from different species of commercial and domestic birds were collected from different provinces of Iran, 19 of which were selected for the current study. Phylogenetic analyses showed that the recent outbreaks have been caused by only one agent, i.e. the distinctive NDV subgenotype VII.1.1 (previously known VIIl) viruses that seem to be circulating predominantly in Iran, but have also been sporadically reported from Iraq among neighbouring countries. At most, 96.3-96.7% BLAST identity to non-Iranian VII.1.1 isolates was observed. Genetic distance values of <1% were indicative of high similarity between the isolates, but the values were approaximately 2% when the current isolates were compared to the earliest recorded Iranian VII.1.1 viruses isolated in 2010. Using Bayesian analysis, annual mutation rates of 1.7156E-3 (strict) and 1.9902E-3 (relaxed) over 11 years were obtained. In addition, we report that our laboratories have not detected any genotype XIII strains since 2011. Following up on previous reports, we concluded that currently, and except in Columbiforms, subgenotype VII.1.1 may likely be the predominant subgenotype in many bird species in Iran despite the subgenotype VII.2 being predominant in neighbouring countries.

Molecular characterization of avian reovirus causing tenosynovitis outbreaks in broiler flocks, Iran.

Avian reoviruses (ARVs) cause arthritis, tenosynovitis, retarded growth, and malabsorption syndrome. After a long time of effective prevention and low rates of viral arthritis/ tenosynovitis in Iran, outbreaks of tenosynovitis in broiler flocks have increased in recent years. Lameness, splay legs, high rate of cull birds, poor performance, uneven birds at harvest, and condemnation at processing cause huge economic losses. In this study, ARVs from the tendons of birds from 23 broiler flocks with marked tenosynovitis were characterized, and their genetic relationship was examined. Analysis of the amino acid sequence of Sigma C protein revealed that all ARVs detected in affected broiler flocks shared genetic homogeneity and this suggests that a single genotype is involved in recent outbreaks. This genotype, so-called "Ardehal strain", is grouped in cluster I with vaccine strains. The amino acid sequence similarity between Ardehal and vaccine strains, including S1133, 1733, and 2408 was less than 80%. As the outbreaks have occurred in progenies of vaccinated flocks, it is proposed here that the difference between vaccine and field strains might contribute to the failure of currently available vaccines to induce protective immunity against Ardehal strain and this led to widespread viral tenosynovitis in Iran.

Including 793/B type avian infectious bronchitis vaccine in 1-day-old chicken increased the protection against QX genotype.

Infectious bronchitis virus (IBV) is a highly infectious pathogen, which affects the respiratory tract, reproductive system, and kidney of chickens. Many different genotypes of IBV are recognized which cause different clinical manifestations. According to the antigenic differences, different serotypes of the virus do not cross-protect. Massachusetts serotype induces the best cross-protection against other serotypes. Recently, the IBV QX genotype has been detected in Iran. QX genotype causes permanent damage to the oviduct in layer and breeder flock if it occurs in the early life cycle. In this study, we compared two vaccination program using 793/B type and Massachusetts type vaccine. One-day-old SPF chickens were divided into four groups. Groups 1 and 2 were unvaccinated groups. Group 3 was vaccinated with the H120 vaccine at day 1 and 793/B at day 14 (eye drop), and group 4 was vaccinated with H120+793/B (eye drop) on the first day and 793/B at day 14. Groups 2, 3, and 4 challenged (oculonasal) with QX genotype (104 EID50) at day 35. Five days post challenge, the sample were clollected for ciliostasis test, histopathology, and quantitative real-time RT-PCR from trachea, lung, and kidneys. Results showed that two vaccination programs created more than 80% of protection against challenge virus, but no significant difference was recorded between two programs. Based on our results, it can be concluded that vaccination with two mixed vaccines (H120+793/B) on the first day of the life of a chick does not make any difference in comparison to single vaccine (H120) in reducing of pathological damages and viral load. As long as the second vaccination against IB may not be applied properly in farm situation, applying the mixture of 793/B type vaccine with H120 at day 1 (ocular or spray) may help to increase vaccination program efficacy.

Full-genome characterization and genetic analysis of a H9N2 virus in commercial broilers in Iran, 2017.

Since 1998, Iran's poultry industry has faced several outbreaks of low pathogenic avian influenza H9N2. Tissue samples were collected from a broiler flock with respiratory symptoms in autumn 2017. After that, virus isolation and confirmation of H9N2 using RT-PCR, sequencing, and bioinformatic analysis for all eight genes were performed. The phylogenic analysis revealed HA gene of recent Iranian isolate (A/chicken/Mashhad/UT-Barin/2017) which was clustered in G1 sublineage. In addition, all eight genes of the virus were placed with Pakistani isolates of 2015 in separate group. Based on amino acid motif KSSR in HA cleavage site, the UT-Barin is considered as low pathogenic avian influenza with eight HA and seven NA potential N-glycosylated sites. No evidence was detected regarding adamantane and neuraminidase inhibitors' drug's resistance. Multiple point mutations were observed in all genes that were responsible for increasing virulence of the virus for avian host and also increasing affinity to mammalian host cells.

Emergence of a virulent genotype VIIi of Newcastle disease virus in Iran.

Newcastle disease (ND) is a contagious viral disease affecting numerous avian species, particularly domestic poultry, and causes devastating outbreaks. In spite of its endemicity and importance in Iran, data on the genetic characterization of ND virus (NDV) are scarce. An alarming issue that has just been raised is the occurrence of ND outbreaks with unexpected high mortality and severe clinical signs. The present study was conducted to characterize the emerging NDV genetically. An NDV strain, isolated in 2017 from commercial broilers showing severe nervous and enteric signs, was completely sequenced and found to be 15,192 nucleotides in length. The phylogenetic analysis demonstrated that the virus belonged to subgenotype VIIi, a subgenotype with potential panzootic features which has recently emerged in the Middle East and Asia. The supporting genetic pattern obtained from the complete genome, fusion and haemagglutinin gene analysis showed close relationship of the isolate with Pakistani VIIi NDVs. The analysis of the F protein showed a polybasic amino acid motif and a phenylalanine at position 117 at the cleavage site, which is a characteristic of virulent strains. The isolate showed significant differences from the previously characterized NDV strains from commercial and rural chickens in Iran. This may describe the importance of the illegal trade of pet birds from neighbouring countries leading to the emergence of new genotypes. This study introduces a newly emerging NDV VIIi subgenotype in Iran. This investigation emphasizes the necessity of effective control strategies.

Prevalence of avian influenza (H9N2) in commercial quail, partridge, and turkey farms in Iran, 2014-2015.

Avian influenza virus (AIV) H9N2 subtype is endemic in Iran and causes substantial economic loss to the growing poultry industry within the country. In this study, a cross-sectional analysis was carried out to determine the sero-prevalence of H9N2 in several commercial farms between the years 2014 and 2015. The comparison of the mean of serum titers and the ratio of sero-positive birds between all units were analyzed using one-way ANOVA test. In 2014, a total of 77 farms (58 turkey farms, 14 quail farms, and 5 partridge farms) and 894 birds (682 turkeys, 154 quails, and 58 partridges) were sampled while in 2015, a total of 69 farms (54 turkey farms, 8 quail farms, and 7 partridge farms) and 856 birds (675 turkeys, 105 quails, and 76 partridges) were sampled. Of that, 52 of 77 sampled farms (67.5%) and 437 of 894 samples (48.9%) were positive for H9N2 in 2014 while. Forty-one of 69 farms (59.4%) and 307 of 856 sera (35.9%) were positive in 2015. Furthermore, the mean titer of partridge farms was significantly lower than that of turkey farms (p < 0.01) and the mean percentage of sero-positive turkey farms was significantly higher than partridge farms (p < 0.01) in 2014. In 2015, no significant difference was observed between the mean sera titer amongst farms and percentage of sero-positive birds (p > 0.05). Our results indicated that H9N2 is circulating in these farms. Since many more such farms are being established for operations, in addition to the threat of emergence and continuous reemergence of the disease in these farms, enhanced veterinary biosecurity measures on farms are required for mitigation.

Co-circulation of three clusters of 793/B-like avian infectious bronchitis virus genotypes in Iranian chicken flocks.

Avian infectious bronchitis (IB) is an acute and highly contagious viral disease causing severe economic losses in the poultry industry. The 793/B IB virus is an important infectious bronchitis virus (IBV) genotype currently circulating in several countries, including Iran. One hundred confirmed IBV samples (between 2014 and 2015; from 15 provinces in Iran) were selected for genotyping based on S1 sequencing. After phylogenetic analysis, it was found that 30% of the IBV isolates belonged to the 793/B genotype. Results showed that the Iranian 793/B-like IBV isolates could be divided in to three clusters: 4/91-like (50%), 1/96-like (40%), and IB88-like (10%). The sequence similarity between Iranian 793/B-like IBV isolates is 87.69%-100%. The highest identity is between the 4/91 and IB88 clusters (96.38%), and the lowest similarity is between the 1/96 and IB88 clusters (87.62%). This study provides a comprehensive analysis of 793/B-type IBV in Iran and characterization of IBV molecular epidemiology in the country.

Phylogenetic analysis of H9N2 avian influenza viruses in Afghanistan (2016-2017).

Avian influenza A virus (AIV) subtype H9N2 is the most prevalent subtype found in terrestrial poultry throughout Eurasia and has been isolated from poultry outbreaks worldwide. Tracheal tissue specimens from 100 commercial broiler flocks in Afghanistan were collected between 2016 and 2017. After real-time RT-PCR, AI-positive samples were further characterized. A part of the HA gene was amplified using RT-PCR and sequenced. The results of real-time RT-PCR showed that 40 percent of the flocks were AI positive. Phylogenetic studies showed that these H9N2 AIVs grouped within the Eurasian-lineage G1 AIVs and had a correlation with H9N2 AIV circulating in the poultry population of the neighboring countries over the past decade. Analysis of the amino acid sequence of HA revealed that the detected H9N2 viruses possessed molecular profiles suggestive of low pathogenicity and specificity for the avian-like SAα2,3 receptor, demonstrating their specificity for and adaptation to domestic poultry. The results of the current study provide great insights into H9N2 viruses circulating in Afghanistan's poultry industry and demonstrate the necessity of planning an applied policy aimed at controlling and managing H9N2 infection in Afghan poultry.

Clade 2.3.4.4 avian influenza A (H5N8) outbreak in commercial poultry, Iran, 2016: the first report and update data.

In 2010, H5N8 highly pathogenic avian influenza (HPAI) viruses of the A/Goose/Guangdong/1/1996 lineage dramatically affected poultry and wild birds in Asia, Europe, and North America. In November 2016, HPAI H5N8 was detected in a commercial layer farm in Tehran province. The diagnosis was based on real-time reverse transcriptase PCR (RRT-PCR) and sequencing of haemaglutinin (HA) and neuraminidase (NA) genes from suspected samples. Genetic and phylogenetic analysis of the HA gene demonstrated that the Iranian HPAI H5N8 viruses belong to the HPAI H5 virus clade 2.3.4.4 and cluster within group B (Gochang-like). In particular, the highest similarity was found with the sequences of the HPAI H5N8 identified in Russia in 2016. To our knowledge, this clade has not been previously detected in Iran. Previous HPAI A (H5) epidemic in Iran occurred in 2015 and involved exclusively viruses of clade 2.3.2.1c. These findings indicate that Iran is at high risk of introduction of HPAI H5 of the A/Goose/Guangdong/1/1996 lineage from East Asia and highlight the need to maintain adequate monitoring activities in target wild and domestic bird species for HPAI early detection. This study is useful for better understanding the genetic and antigenic evolution of H5 HPAI viruses in the region and the world.

Genotyping of infectious bronchitis viruses from broiler farms in Iraq during 2014-2015.

Infectious bronchitis virus (IBV) is one of the most critical pathogens in the poultry industry, causing serious economic losses in all countries including Iraq. IBV has many genotypes that do not confer any cross-protection. This virus has been genotyped by sequence analysis of the S1 glycoprotein gene. A total of 100 tracheal and kidney tissue specimens from different commercial broiler flocks in the middle and south of Iraq were collected from September 2013 to September 2014. Thirty-two IBV-positive samples were selected from among the total and were further characterized by nested PCR. Phylogenetic analysis revealed that isolates belong to four groups (group I, variant 2 [IS/1494-like]; group II, 793/B-like; group III, QX-like; group IV, DY12-2-like). Sequence analysis revealed nucleotide sequence identities within groups I, II, and III of 99.68 %-100 %, 99.36 %-100 %, and 96.42 %-100 %, respectively. Group I (variant 2) was the dominant IBV genotype. One Chinese-like recombinant virus (DY12-2-like) that had not been reported in the Middle East was detected. In addition, the presence of QX on broiler chicken farms in the area studied was confirmed. This is the first comprehensive study on the genotyping of IBV in Iraq with useful information regarding the molecular epidemiology of IBV. The phylogenetic relationship of the strains with respect to different time sequences and geographical regions displayed complexity and diversity. Further studies are needed and should include the isolation and full-length molecular characterization of IBV in this region.

The complete genome sequence of a new fowl adenovirus (Fadv-4) strain from a recent outbreak in a chicken farm in Iran.

The whole genomic sequence of fowl adenovirus C (FAdV-4) strain FAdV-4/Pasouk, isolated from chickens with hepatitis-hydropericardium syndrome (HHS) from an outbreak in Iran, has been deposited in GenBank under accession number ON652872. Notably, this FAdV-4 isolate exhibited significant genetic similarities to contemporary isolates originating from China, indicating a shared ancestry.

Molecular Characterization and Phylogenetic Analysis of Marek's Disease Virus in Iran.

Marek's disease (MD) is a highly contagious, lymphoproliferative poultry disease caused by the oncogenic herpesvirus, serotype 1 Marek's disease virus (MDV-1), or Gallid herpesvirus 2 (GaHV-2). MDV strains have shown a continued evolution of virulence leading to immune failure, and MD cases continue to occur or surge. Meq, the major MDV-1 oncoprotein, induces T-cell neoplastic transformation through several mechanisms including inhibition of apoptosis, cell cycle regulation, and serum-anchorage independent growth. There is no current information on the MDV serotypes and pathotypes circulating in vaccinated commercial farms in Iran, where the birds are vaccinated at the hatchery with GaHV-2 and Meleagrid herpesvirus 1 (MeHV-1) vaccines. This study reports the molecular characterization of a GaHV-2 strain detected in 19 flocks of Iranian layer farms exhibiting MDV-1-like clinical signs and visceral lymphomas. Based on sequencing and phylogenetic analysis of the Meq gene, the Iranian GaHV-2 isolates could be divided into two separate clades regarding molecular features. The clade containing strains was closely related to Italian, Indian, and Hungarian virulent isolates, and the clade was related to American very virulent plus (vv+) isolates. For the first time, the MDV-1 virus was characterized by an outbreak in poultry flocks in Iran. Although MDV-1 strains obtained in Iran's present outbreak are presumably related to virulent (v) and vv+ pathotypes based on nucleotide, amino acid, and phylogenetic analysis of the viruses, they are not confirmed so far. Thus, it is highly recommended to perform further analyses to demonstrate the pathotype characteristics in vivo.

Caracterización molecular y análisis filogenético del virus de la enfermedad de Marek en Irán. La enfermedad de Marek (MD) es una enfermedad altamente contagiosa linfoproliferativa en la avicultura causada por el herpesvirus oncogénico, el virus de la enfermedad de Marek de serotipo 1 (MDV-1) o Gallid herpesvirus 2 (GaHV-2). Las cepas del virus de Marek han mostrado una evolución continua de virulencia que conduce a una falla inmunológica, y los casos de Marek continúan ocurriendo o aumentando. El gene Meq, codifica la principal oncoproteína de MDV-1, induce la transformación neoplásica de células T a través de varios mecanismos que incluyen la inhibición de la apoptosis, la regulación del ciclo celular y el crecimiento independiente del anclaje sérico. No hay información actual sobre los serotipos y patotipos del virus de Marek que circulan en las granjas comerciales vacunadas en Irán, donde las aves se vacunan en la planta de incubación con las vacunas GaHV-2 y Meleagrid herpesvirus 1 (MeHV-1). Este estudio reporta la caracterización molecular de una cepa del Gallid herpesvirus 2 detectada en 19 lotes de granjas de aves de postura iraníes que presentaron signos clínicos sugestivos del serotipo 1 del virus de la enfermedad de Marek y linfomas viscerales. Según la secuenciación y el análisis filogenético del gene Meq, los aislamientos iraníes de GaHV-2 podrían dividirse en dos clados separados con respecto a las características moleculares. El clado que contenía las cepas estaba estrechamente relacionado con los aislados virulentos de Italia, India y de Hungria y el clado estaba relacionado con los aislados americanos muy virulentos plus (vv+). Por primera vez, el serotipo 1 del virus de la enfermedad de Marek se caracterizó por un brote en parvadas avícolas en Irán. Aunque las cepas del virus de Marek, serotipo 1 obtenidas en el brote actual de Irán están presuntamente relacionadas con patotipos virulentos (v) y muy virulentos plus según el análisis de nucleótidos, aminoácidos y filogenético de los virus, hasta el momento no se han confirmado. Por lo tanto, se recomienda realizar más análisis para demostrar las características del patotipo in vivo.