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Infectious laryngotracheitis (ILT) is an economically important respiratory disease of poultry that affects the poultry industry worldwide. The disease is caused by gallid herpesvirus I (GaHV-1) a member of the genus Iltovirus, family Herpesviridae, subfamily Alphaherpesvirinae. The current incidence of the disease is heavily influenced by live-att...
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Infectious Laryngotrachitis is an important respiratory disease of chicken caused by gallid herpes virus-І belonged to family Herpesviridae , subfamily Alphaherpesvirinae, genus Iltovirus The disease has little or no previous documented data in the country. The study was conducted from November 2022 to June 2022 by a cross-sectional study design wi...
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... In the recent past reemergence of ILT were being reported especially from state of Tamil Nadu [3][4][5][6][7][8][9] . It has been reported that Infectious laryngotracheitis virus (ILTV) is one of the re-emerging diseases across the world [10] . The clinical cases of ILT in field conditions may be observed either as severe acute form with prominent clinical signs like conjunctivitis, nasal discharge, dyspnoea, coughing and expectoration of bloody mucus or as very mild form with no major clinical signs. ...
... It causes inflammation of the upper respiratory tract, heavy mucous discharge, cough and breathing difficulties, swelling of the infraorbital sinuses, decreased egg production and weight loss [5,6]. The disease is characterized by high morbidity (90-100%) and variable mortality (5-70%), most commonly from 10 to 20% [7]. Severe forms of the disease are characterized by severe dyspnea, expectoration of bloody mucus and high mortality due to suffocation [3,8]. ...
... Hens with a more severe clinical picture in our study had symptoms such as panting and stretching of the head and neck with an open beak, the so-called "hunger for air", while coughing up blood was not recorded. Coughing up blood occurs in acute cases and depends on the virulence of the virus [3,7]. The clinical picture of the disease in many cases does not include the acute signs (nasal discharge, lacrimation, moist rales, expectoration of blood, etc.), which may be a feature of a virus of low pathogenicity [17] or reflect immunity stimulation by vaccination. ...
... In addition to milder and more severe respiratory symptoms, unilateral or bilateral swelling of the head, nasal discharge, inflammation of the conjunctiva of the eye, increased tearing, closed one or both eyes were observed. These symptoms have also been described by other authors [7,10,21]. With the development of the disease, there was a loss of body weight due to the reduction of food and water consumption, which is a very common accompanying symptom [12]. ...
Infectious laryngotracheitis (ILT) is a respiratory disease of poultry characterized by high morbidity and variable mortality. ILT is caused by Gallid alpha herpesvirus-1 (GaHV-1), which is transmitted horizontally and most susceptible are chickens older than 4 weeks. After almost two decades since last appearance of this disease in Vojvodina, an outbreak occurred from April 2020 to August 2021 on five laying hen farms and one broiler breeder flock farm. Clinical signs were mild to severe respiratory symptoms, unilateral or bilateral head swelling, serous nasal discharge, conjunctivitis and increased tearing. There was a decrease in feed consumption (2.1–40.0%) and egg production (2.7–42.0%), weight loss and mortality increased (0.8–31.5%). Pathomorphological changes were localized in the upper respiratory tract. Total of 200 carcasses were examined; 40 pooled samples were analyzed by PCR, and 40 by bacteriological analysis. ILT virus was confirmed in tracheal tissue samples. Infected flocks were not vaccinated against this disease. Five flocks had coinfection with Avibacterium paragallinarum. Three-to-four weeks after the first reported case in the flock, clinical symptoms had ceased. Future control and prevention strategies will involve the procurement of flocks vaccinated by recombinant vaccine or the registration of live attenuated vaccines and their use during the rearing period.
... Epizootics of the infection have recently emerged in the United States (USA), Europe, Australia, and Egypt, which were found to be derived from the CEO vaccines that regained virulence and became the primary source of outbreaks [3,[11][12][13][14] In addition to the live viral vaccines, viral vector vaccines (also known as recombinant vaccines) were generated to fend off ILT. Two commercial viral vector vaccines are available, which differ according to the vector backbone. ...
... The FPV viral vector vaccine carries glycoprotein B and UL32 genes of GaHV-1 (FPV-LT) [15]. In comparison, HVT viral vector vaccine carries glycoprotein D and I, which form part of the outer coat of GaHV-1 that provokes immunity against both GaHV-1 and Marek's disease (HVT-LT) [12,16]. Both types of viral vector vaccines are administered on either 18-dayold chicken embryos through in ovo route or one-day-old chicks through the subcutaneous route. ...
... Both types of viral vector vaccines are administered on either 18-dayold chicken embryos through in ovo route or one-day-old chicks through the subcutaneous route. However, the FPV vector vaccine can also be administered with a wing web vaccination [12]. The lack of bird-to-bird horizontal transmission abolishes the revert to virulence, which has an essential advantage of FPV-LT and HVT-LT. ...
Infectious laryngotracheitis (ILT) is an economically crucial respiratory disease of poultry that affects the industry worldwide. Vaccination is the principal tool in the control of the disease outbreak. In an earlier study, we comprehensively characterized the circulating strains in Egypt and identified both CEO-like and recombinant strains are dominant. Herein, we investigated the pathogenicity of two virulent strains representing the CEO-like (Sharkia_2018) and recombinant strain (Qalubia_2018). Additionally, we evaluated the efficacy of different commercial vaccines (HVT-LT, CEO, and TCO) against the two isolates in terms of the histopathological lesion scores and the viral (gC) gene load. A total of 270 White Leghorn-specific pathogen-free male chicks were divided into nine groups of 30 birds, each housed in separate isolators. Birds were distributed as follows; one group was non-vaccinated, non-challenged, and served as a negative control. Two groups were non-vaccinated and infected with the two isolates of interest and served as a positive control to test the pathogenicity. Six groups were vaccinated and challenged; two groups were vaccinated with vector vaccine at one day old. The other four groups were vaccinated with either the CEO-or TCO-vaccine (two groups each) at four weeks of age. Three weeks after vaccination, birds were infected with the virulent ILTV isolates. The larynx, trachea, and harderian gland samples were taken at 1, 3, and 7 days post-infection for histopathological lesion score and molecular detection. Notably, The recombinant strain was more virulent and pathogenic than CEO-like ILTV strains. Moreover, the TCO vaccine was less immunogenic than the vector and CEO vaccines.
... This substitution has already been reported in (JQ083494.2-ILT-Laryngo vaccine) ( Table 3), This indicates that vaccine strains may have given rise to field strains [14,51]. In addition to the Latent hypothesis of ILTV and his ability to periodically reactivate when affected birds are exposed to stress conditions like as adverse weather conditions, nutrient deficiencies, transportation, and the early stages of laying [17], all of this suggested that the vaccine strain may be the reason of outbreaks. ...
Infectious laryngotracheitis (ILT) is a viral respiratory illness in poultry that causes massive financial losses. This research aimed to isolate and identify the ILT virus in suspected outbreaks of broiler flocks in Egypt during 2020–2021, besides investigating its genetic link with other circulating strains. Real-time-PCR was used to test 57 samples taken from unvaccinated broiler farms. Ten samples are positive for ILTV, and the virus is being isolated in SPF chicken embryos. The Sanger sequencing was used to conduct (partial) sequencing of the infected cell protein4 gene (ICP4) for eight isolates. Phylogenetic analysis conducted Maximum Likelihood, comparative sequencing analysis of ICP4 of strains under study with vaccination ILT reference strains reveled that all isolates were clustered into two major groups. The (OM291843and OM291846) clustered together with the chicken embryo origin vaccine strains (IV and V group). The remaining six strains belong to the TCO vaccine(I, II and III group). The total sequence similarity between the strains under study and the various Egyptian strains varied from (97 to 100%) while the similarity with TCO or chicken embryo origin -vaccine strains ranged from (95to 100%). There were no deletions detected in the 272–283-bp region of the ICP4 gene. Detection of arginine to methionine substitutions at position 180 (R180M) and change of Serine to Asparagine at position 227 (S227N) in the (OM291843 and OM291846) which were previously described in chicken embryo origin -vaccine strains. This reveals that field strains may have evolved from vaccine strains, notably identification of non-synonymous substitutions which might be linked to the virulence strains’ attenuation. Finally, independent of geographical distribution, both chicken embryo origin-vaccine-like and TCO-Vaccine-like virus strains were circulating in Egyptian non-vaccinated broiler flocks in 2020 and 2021. Despite their genetic differences, both viruses caused significant illnesses in the field.
... Additional contributing factors for ILT outbreaks in meat chickens include the presence of large populations of susceptible hosts (as broilers are not routinely vaccinated), breaches in biosecurity, and more frequent movement of litter and birds. Variable initial vaccine take following drinking water vaccination with a subsequent bird-to-bird transmission of vaccine virus has been reported in meat chicken flocks (9), and bird-to-bird passage of vaccine virus can cause reversion to virulence and result in disease outbreaks (10,11). ...
Population-level sampling based on qPCR detection of infectious laryngotracheitis virus (ILTV) in poultry dust can be used to assess ILT vaccination outcomes following mass administration in drinking water. We report on the field application of this approach to assess the success of vaccine administration and its use in ILT outbreak control in meat chickens. In Study 1, dust samples were collected from 26 meat chicken flocks at 0, 4, 7, 14, and 21 days post drinking water vaccination (DPV) given between 7 to 13 days of age with the Serva or A20 live attenuated ILT vaccines. Unexpectedly, ILTV DNA was detected in dust samples collected prior to vaccination in 22/26 flocks. Typing revealed that the detected ILTV was different from the vaccine virus. To determine whether the detected ILTV DNA was from active infection or carryover of a noninfectious virus, Study 2 was implemented in 14 additional flocks with dust samples collected at 0, 7, 14, and 21 DPV and tracheal swabs collected from 15 birds/flock at 0 and 21 DPV. The results indicated that there was active infection with ILTV in those flocks before vaccination. This approach contributed to a statewide control program resulting in the eradication of ILT from South Australia as confirmed by negative ILTV test results for dust samples from 50 flocks and the absence of clinical ILT. These findings show that ILTV infection prior to vaccination is common in outbreak situations and that dust samples must be collected at 0 and 7 DPV for meaningful interpretation of vaccination outcomes and ILTV status. Comparatively low-cost dust testing during an outbreak, coupled with typing information, greatly assisted with decision making and control strategies during a major outbreak, including confirmation of the absence of infection in the final stages.
... Since immunodominant epitopes are very close, it is not possible to distinguish ILTV strains by serological techniques, and therefore this virus is known as a single serotype. Although there are different forms of ILT, highsequence similarities among ILTV strains complicate their molecular characterization (Guy and Garcia, 2008;Ou and Giambrone, 2012;Menendez et al., 2014). ILTV strains have been initially differentiated by restriction endonuclease analysis of viral DNA but routine RFLP analysis has limitations due to the need for high purity of the viral genome. ...
... The laryngotracheitis virus has always been an important pathogen of concern for the modern poultry industry (Menendez et al., 2014). Although biosecurity is the basis for ILT control, vaccination is used to control the disease worldwide (Dufour-Zavala, 2008;Chin et al., 2009). ...
... In Turkey, the ILT outbreak among laying hen flocks was first reported in 2003 in Elazig. The affected flocks by this epidemic exhibited severe symptoms (Gulacti et al., 2007, 2014, 2016, some poultry farms in Central and Eastern Anatolia in Turkey had outbreaks resulting in mild infections (Menendez et al., 2014;Aras et al., 2018;Kaya and Akan, 2018). ...
Infectious laryngotracheitis (ILT) is an economically important respiratory disease affecting the poultry industry worldwide. The aim of this study was to characterize the Turkish ILT virus (ILTV) isolates by sequencing and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). ILTV isolates obtained from laying hens in Turkey in 2003 and 2018 were used in this study. The isolates were analyzed for ICP4, gG, gE and TK gene regions by PCR. The amplification products were used in RFLP analysis to determine the differences among the isolates. Sequence analyses of TK and ICP4 regions were carried out and a phylogenetic tree was formed by using the Maximum Likelihood method. Nucleotide identity values were then calculated among five isolates and other strains/isolates in Genbank. In addition, about 200 amino acid sequences of the start and end regions of the ICP4 gene were compared to other strains in Genbank. PCR-RFLP analysis indicated that Turkish ILTV isolates were low-virulent. In general, the nucleotide sequence similarities of the TK and ICP4 gene regions among Turkish isolates and others was more than 95% (lower in some Egyptian and Bangladeshi strains, 41 and 45% respectively); in the amino acid sequence, it was close to 100%. As a result, PCR-RFLP results were similar in many gene regions. However, evolutionary analysis of ICP4 and TK gene regions did not yield reliable results based on geographic distribution or pathogenicity levels. For this purpose, different methods, such as Bayesian analysis or the involvement of samples from different gene regions can yield more reliable results, just like whole-genome sequences.
... Live attenuated vaccines (LAVs) were developed by multiple passages in embryonated eggs recognized as chicken embryo origin (CEO) [11], or by multiple passages in tissue culture recognized as tissue culture origin (TCO) [12]. Despite their high effectiveness, GaHV-1 LAVs, particularly the CEO vaccines, carry a high risk of reversion to virulence [13] resulting in outbreaks [14]. e recombinant viral vector vaccines were developed as safest alternatives to the LAVs. ...
... Yet, there are supposed reports of the CEO and TCO vaccines usage by private poultry farms. e use of live attenuated ILT vaccines, particularly of the CEO versions, has been linked with reversion to the virulent form causing a full-blown disease outbreak [13,14]. erefore, it can be speculated that the highest seroprevalence reported in this study could be the result of vaccine-induced immunity or reverted-vaccine-induced infection. ...
Infectious laryngotracheitis (ILT) is a disease of high economic consequence to the poultry sector. Gallid herpesvirus 1 (GaHV-1), a.k.a infectious laryngotracheitis virus (ILTV), under the genus Iltovirus, and the family Herpesviridae, is the agent responsible for the disease. Despite the clinical signs on the eld suggestive of ILT, it has long been considered nonexistent and a disease of no concern in Ethiopia. A cross-sectional study was conducted from November 2020 to June 2021 in three selected zones of the Amhara region (Central Gondar, South Gondar, and West Gojjam zones), Ethiopia, with the objective of estimating the seroprevalence of ILTV in chickens and identifying and quantifying associated risk factors. A total of 768 serum samples were collected using multistage cluster sampling and assayed for anti-ILTV antibodies using indirect ELISA. A questionnaire survey was used to identify the potential risk factors. Of the 768 samples, 454 (59.1%, 95% CI: 0.56-0.63) tested positive for anti-ILTV antibodies. Mixed-e ect logistic regression analysis of potential risk factors showed that local breeds of chicken were less likely to be seropositive than exotic breeds (OR: 0.38, 95% CI: 0.24-0.61). In addition, factors such as using local feed source (OR: 6.53, 95% CI: 1.77-24.04), rearing chickens extensively (OR: 1.97, 95% CI: 0.78-5.02), mixing of di erent batches of chicken (OR: 14.51, 95% CI: 3.35-62.77), careless disposal of litter (OR: 1.62, 95% CI: 0.49-4.37), lack of house disinfection (OR: 11.05, 95% CI: 4.09-47.95), lack of farm protective footwear and clothing (OR: 20.85, 95% CI: 5.40-80.45), and careless disposal of dead chicken bodies had all been associated with increased seropositivity to ILTV. erefore, implementation of biosecurity measures is highly recommended to control and prevent the spread of ILTV. Furthermore, molecular con rmation and characterization of the virus from ILT suggestive cases should be considered to justify the use of ILT vaccines.
... ILT is a disease with a worldwide distribution and endemic in countries with high density poultry production in geographically concentrated commercial farms. Usually, live attenuated vaccines, along with biosecurity, are the control measures in regions where cyclic outbreaks occur (Guy & García 2008, Menendez et al. 2014. In Brazil, recombinant vaccines are used to control ILT present in three quarantined regions with large numbers of layers. ...
The effectiveness of vectored recombinant vaccines to control infectious laryngotracheitis (ILT) in chickens from a region (State of Minas Gerais, Brazil) with ~10 million layers was evaluated under field conditions from 2014-2018. During this period, only recombinant turkey herpesvirus (rHVT) or fowl poxvirus (rFPV) vaccines that express antigens of infectious laryngotracheitis virus (Gallid herpesvirus-1; GaHV-1) were used. Layer chickens (n=1,283), from eight different egg-producing companies, were individually sampled and examined (active surveillance), and in instances when government poultry health veterinarians were notified due to respiratory disease (passive surveillance). Clinical, macroscopic, and histopathology examinations were performed to diagnose ILT as well as molecular techniques for the detection and characterization of the GaHV-1 DNA from the trachea and trigeminal ganglia (TG). The layer hens sampled and examined belonged to flocks and farms that used different vaccination protocols (non-vaccinated, single dose vaccination, and prime/boost vaccination). This is the first long-term field study of the effectiveness of ILT vectored vaccines in a high-density multiple age layer hen region. Using various diagnostic methods, the occurrence of GaHV-1 infection and ILT clinical disease in layer hens vaccinated with vectored recombinant vaccines in one quarantined region of Brazil were investigated. The number of ILTV positive chickens by PCR and ILT clinical disease cases was lower in farms when all chickens were vaccinated with at least one vaccine. However, the difference in the detection rates of GaHV-1 infection was significant only when compared farms with prime/boost and farms using single dose of HTV-LT.
... It is an acute, highly contagious upper-respiratory infectious disease of chickens, which was first described in the USA in 1925 (May and Tittsler, 1925). It is one among the emerging and re-emerging diseases of poultry gradually spreading worldwide and affects chickens of all age groups (Menendez et al., 2014). This disease causes severe economic losses to poultry industry due to decrease in egg production, weight loss, susceptibility to other respiratory infections, high mortality and morbidity (Guy and Bagust, 2003). ...
Background: Infectious laryngotracheitis (ILT) is an economically important viral respiratory disease in poultry. Recently, re-emergence of Infectious laryngotracheitis virus (ILTV) has been reported in several countries including India. The current study aimed to evaluate the poultry flocks of Tamil Nadu with circulating GaHV-1 and to elucidate the origin of the virus involved in the outbreak. Methods: In this study, a molecular based survey on the overall occurrence of natural cases of Infectious laryngo-tracheitis in poultry flocks from Tamil Nadu, India were performed. Pathological findings in respiratory and secondary lymphoid organs like caecal tonsils and harderian gland was carried out. The PCR technique targeting Infected Cell Protein-4 (ICP4) gene along with molecular characterization was performed. Result: The overall prevalence rate in the outbreak was 42.86% with highest incidence in layer flocks (62.85%) than the broiler flocks (22.85%). The highest susceptible age groups were between 20-30 weeks old. Tracheal pathology revealed epithelial sloughing, syncytial cell formation, eosinophilic intranuclear inclusion bodies and heterophilic exudation microscopically. Partial genome sequencing and phylogenetic analysis of ICP4 gene revealed high genetic homology between field isolates and the virulent strains from Turkey, Germany, China and Brazil. In the present study, along with pathological findings, a rapid and sensitive PCR assay was used for detection of ILT virus specific ICP4 gene in commercial poultry farms in the region.
... Infectious laryngotracheitis virus (ILTV) causes a common respiratory disease of chickens that imposes a substantial economic load on the poultry industry. ILTV is a DNA virus that belongs to the Gallid alphaherpesvirus 1 (GaHV-1) species of the Alphaherpesvirinae subfamily within Herpesviridae family [1][2][3]. The disease causes respiratory distress and leads to significant production losses due to diminished egg production, poor feed conversion rates, high mortality rates, and increased susceptibility to other respiratory tract pathogens [2,4]. ...
Infectious laryngotracheitis (ILT) is a viral disease of chickens’ respiratory system that imposes considerable financial burdens on the chicken industry. Rapid, simple, and specific detection of this virus is crucial to enable proper control measures. Polymerase chain reaction (PCR)-based molecular tests require relatively expensive instruments and skilled personnel, confining their application to centralized laboratories. To enable chicken farms to take timely action and contain the spread of infection, we describe a rapid, simple, semi-quantitative benchtop isothermal amplification (LAMP) assay, and a field-deployable microfluidic device for the diagnosis of ILTV infection in chickens. Our assay performance was compared and favorably agreed with quantitative PCR (qPCR). The sensitivity of our real-time LAMP test is 250 genomic copies/reaction. Clinical performance of our microfluidic device using samples from diseased chickens showed 100% specificity and 100% sensitivity in comparison with benchtop LAMP assay and the gold-standard qPCR. Our method facilitates simple, specific, and rapid molecular ILTV detection in low-resource veterinary diagnostic laboratories and can be used for field molecular diagnosis of suspected ILT cases.
