A Mixed Methods Investigation Examining the PrEP Cascade Among 13-18-Year-Old Latino Adolescent Sexual Minority Men.

Latino adolescent sexual minority men (ASMM) are at high risk of HIV. Limited research has explored the impact of parent-adolescent communication and beliefs on PrEP adoption among Latino ASMM. Our objective was to examine how parental support and beliefs influence decisions regarding PrEP use. We analyzed PrEP-related attitudes and behaviors within a national cohort of 524 Latino ASMM aged 13-18. Out of the participants, 60.5% were suitable for PrEP. Among them, 59.7% were in the precontemplation stage (stage 1), indicating a lack of willingness or belief of unsuitability. However, 86.4% moved to reach the contemplation stage (stage 2), demonstrating willingness and suitability for PrEP. Only 16.8% moved on to the PrEParation stage (stage 3), indicating their intention to start using PrEP. Furthermore, 4.3% progressed to the PrEP action stage and initiation (stage 4), signifying they had received a prescription, and all reported high adherence (stage 5). Factors associated with reaching later stages included older age, parental support of sexual orientation, and previous HIV/STI testing. The qualitative findings revealed diverse attitudes towards parental involvement in PrEP care among Latino ASMM, including positive, negative, and ambivalent perspectives. Notably, Spanish-speaking participants expressed specific barriers to PrEP communication between ASMM and their parents. Given that parental support and attitudes emerged as significant factors in both our quantitative and qualitative findings, it is evident that public health approaches aiming to disseminate education and awareness about PrEP to parents and families could alleviate the burden on adolescents to educate their parents and enhance support.

Factors Influencing Engagement Across the Motivational PrEP Cascade Among Latino SMM: A Mixed-Methods Analysis from the Perspectives of Community Providers and Latino SMM.

Latino sexual minority men (SMM) are a highly vulnerable population to HIV, and while pre-exposure prophylaxis (PrEP) has emerged as a promising biomedical tool for HIV prevention among them, its utilization remains disproportionately low in this community despite its potential. Understanding the barriers along the PrEP continuum of care, known as the "PrEP cascade," is crucial for effectively implementing PrEP interventions. Therefore, the objective of our study was twofold: first, to explore the stage of Latino SMM in the PrEP cascade by examining disparities in demographics, social factors, and healthcare aspects; second, to gain insights from healthcare providers who have direct clinical experience with our population regarding the challenges faced by Latino SMM in accessing and adhering to PrEP. Based on the study findings, the majority of participants (n = 74; 49%) were in the contemplation stage, and only one in ten Latino SMM (10.6%) were currently adherent to PrEP. Compared to those who were at least second-generation, first-generation status had a positive association (B = 0.699, SE = 0.208, ß = 0.351, p < .001) with engagement along the PrEP Contemplation Ladder. Conversely, having at least one parent who did not have legal residency, relative to those whose parents were both U.S. citizens or held legal residency documentation, was found to have a negative association (B = - 0.689, SE = 0.245, ß = 0.245, p = .006) with engagement along the PrEP Contemplation Ladder. Additionally, discussing PrEP with a healthcare provider had a positive association (B = 0.374, SE = 0.179, ß = 0.185, p = .038) with engagement along the PrEP Contemplation Ladder. Qualitative results from our study suggest that some Latinos who initially agreed to start using PrEP ended up getting lost in the care pipeline and failed to attend their scheduled appointments. Providers also noted that many patients lacked access to a pharmacy where they felt comfortable obtaining their PrEP prescription, leading them to discontinue use after only a few months. These findings emphasize the importance of considering the unique needs, culture, and background of Latinos, including care delivery and provider attitudes that can facilitate progress through the PrEP cascade.

Experiences of Successful PrEP Uptake Among Adolescent Sexual Minority Men in the United States: A Qualitative Exploration.

Male adolescent sexual minorities are at elevated risk of HIV acquisition yet demonstrate low rates of PrEP uptake. Understanding the experiences of adolescents who have successfully accessed PrEP may inform ways to best support adolescents seeking PrEP. Adolescent sexual minorities (N = 100) who reported utilizing PrEP responded to open-ended items asking about their initial PrEP experiences and advice for others. Qualitative analysis suggested that adolescents' ability to access PrEP is influenced by managing parental involvement and seeking culturally competent health care providers. Additionally, they reported how the benefits and drawbacks of taking PrEP played a role in their PrEP use. Findings suggest that educational PrEP interventions targeted at this population could improve uptake by incorporating discussions on side effects and mental health benefits associated with PrEP use. Structural interventions are warranted that improve adolescents' ability to seek sexual health care independently and make room for parental involvement when adolescents could benefit from their support.

Assessing Feed-Forward Backpropagation Artificial Neural Networks for Strain-Rate-Sensitive Mechanical Modeling.

The manufacturing processes and design of metal and alloy products can be performed over a wide range of strain rates and temperatures. To design and optimize these processes using computational mechanics tools, the selection and calibration of the constitutive models is critical. In the case of hazardous and explosive impact loads, it is not always possible to test material properties. For this purpose, this paper assesses the efficiency and the accuracy of different architectures of ANNs for the identification of the Johnson-Cook material model parameters. The implemented computational tool of an ANN-based parameter identification strategy provides adequate results in a range of strain rates required for general manufacturing and product design applications. Four ANN architectures are studied to find the most suitable configuration for a reduced amount of experimental data, particularly for cases where high-impact testing is constrained. The different ANN structures are evaluated based on the model's predictive capability, revealing that the perceptron-based network of 66 inputs and one hidden layer of 30 neurons provides the highest prediction accuracy of the effective flow stress-strain behavior of Ti64 alloy and three virtual materials.

Acceptability of 'Humpr': An Online Tool to Educate Adolescent Sexual Minority Males About Sexual Networking Applications.

We examined the acceptability of Humpr - an interactive, online tool developed to educate adolescent sexual minority males (ASMM) about how to safely navigate sexual networking applications (SNA). We developed Humpr as part of a larger HIV intervention trial in the U.S. In Humpr, 218 ASMM aged 14-20 (Mage = 17.18) created a mock dating profile, explored simulated user profiles, learned health-related information (e.g. slang indicating HIV/STI risks and/or drug use intentions), and then gave feedback regarding acceptability of the tool. Results showed that Humpr was very well-received, with 94% overall approval rates. Reasons for liking Humpr were evenly split between liking it for educational and entertaining reasons. Participants praised Humpr for its realistic design and interactive interface that allowed them to engage and connect with the tool. The majority (61%) had used SNAs in the past, but many still reported learning something new from Humpr. Participants also appreciated the acknowledgment of SNA use in ASMM and how the education was implemented in an open and judgment-free way. Topics learned from Humpr included how to be safe on SNAs and warning signs for HIV/STI risks. Suggested areas of improvement included having an opt-out option for those who do not wish to participate for any reason (e.g. discomfort) and additional educational content (e.g. consequences of being a minor on SNAs). Taken together, the findings offer preliminary evidence for the potential educational benefits of digital tools like Humpr for ASMM with and without prior SNA exposure.

Características y factores asociados a la mortalidad en pacientes con COVID-19 traqueostomizados: estudio de cohorte retrospectivo en un hospital de Tacna, Perú / Characteristics and factors associated with mortality in tracheostomized patients with COVID-19: a retrospective cohort study in a hospital in Tacna, Peru

RESUMEN Objetivo. Describir las principales características demográficas, clínicas, laboratoriales y terapéuticas e identificar si están asociados con la mortalidad en pacientes traqueostomizados. Material y métodos. Estudio de cohorte retrospectiva en pacientes adultos con diagnóstico de COVID-19, ingresados a UCI (Unidad de Cuidados Intensivos) y que requirieron traqueostomía. Se extrajeron datos demográficos, clínicos, laboratoriales y de tratamiento de las historias clínicas de pacientes que ingresaron al Hospital III Daniel Alcides Carrión de Tacna. Para el análisis de supervivencia se empleó el modelo de riesgos proporcionales de Cox y se calcularon los cocientes de riesgo instantáneos (HR) con sus intervalos de confianza al 95% (IC95%). Resultados. Se evaluaron 73 pacientes, el 72,6% eran hombres, las comorbilidades más comunes fueron obesidad (68,5%), diabetes mellitus tipo 2 (35,6%) e hipertensión arterial (34,2%). El 37% de los participantes fallecieron durante la estancia en UCI. La mediana de tiempo desde la intubación hasta la traqueostomía y la duración de esta fue 17 (RIC: 15−21) y 21 (RIC: 3−39) días, respectivamente. El análisis multivariado mostró que los factores asociados a mortalidad, fueron presentar un valor de procalcitonina > 0,50 ng/dL en el momento de la traqueostomía (HRa: 2,40 IC95%: 1,03−5,59) y el nivel de PaO2/FiO2 menor o igual a 150 mmHg, (HRa: 4,44 IC95%: 1,56−12,60). Conclusiones. Los factores asociados a mortalidad al momento de realizar la traqueostomía fueron presentar un valor de procalcitonina > 0,50 ng/dL y un cociente PaO2/FiO2 menor o igual a 150 mmHg.

ABSTRACT Objective: We aimed to describe the main demographic, clinical, laboratory and therapeutic characteristics and to identify whether they are associated with mortality in tracheostomized patients. Material and methods. Retrospective cohort study in adult patients diagnosed with COVID-19, admitted to ICU (Intensive Care Unit) and requiring tracheostomy. Demographic, clinical, laboratory and treatment data were obtained from the medical records of patients admitted to Hospital III Daniel Alcides Carrión in Tacna. The Cox proportional hazards model was used for survival analysis and hazard ratios (HR) with their 95% confidence intervals (95%CI) were calculated. Results. We evaluated 73 patients, 72.6% were men, the most common comorbidities were obesity (68.5%), type 2 diabetes mellitus (35.6%), and arterial hypertension (34.2%). Thirty-seven percent of the participants died during their stay at the ICU. The median time from intubation to tracheostomy and the duration of tracheostomy was 17 (RIC: 15-21) and 21 (RIC: 3-39) days, respectively. Multivariate analysis showed that the factors associated with mortality were procalcitonin > 0.50 ng/dL at the time of tracheostomy (HRa: 2.40 95%CI: 1.03-5.59) and a PaO2/FiO2 ratio less than or equal to 150 mmHg (HRa: 4.44 95%CI: 1.56-12.60). Conclusions. The factors associated with mortality at the time of tracheostomy were procalcitonin > 0.50 ng/dL and a PaO2/FiO2 ratio less than or equal to 150 mmHg.

Stakeholders' Perspectives About Cultural Strategies to Support PrEP for Latino Sexual Minority Men.

Compared with non-Latino White sexual minority men, Latino sexual minority men (LSMM) have lower engagement with HIV pre-exposure prophylaxis (PrEP) and likelihood of discussing PrEP with a health care provider. The overall goal of the current study was to collect data from community stakeholders to inform the integration of culturally relevant factors into an empirically supported PrEP prevention program. Between December 2020 and August 2021, 18 interviews were conducted with 18 stakeholders with experience delivering health and social services. Themes identified are: (1) stakeholders' perspectives of new HIV infections among LSMM; (2) stakeholders' perspectives of general cultural variables; and (3) the development of culturally tailored programs. Our findings demonstrate how culturally competent stakeholders can leverage their established rapport and trust to reduce the negative effects of machismo and/or homophobia in the Latinx community to promote HIV prevention.

Characteristics and factors associated with mortality in tracheostomized patients with COVID-19: a retrospective cohort study in a hospital in Tacna, Peru. / Características y factores asociados a la mortalidad en pacientes con COVID-19 traqueostomizados: estudio de cohorte retrospectivo en un hospital de Tacna, Perú.

OBJECTIVE: We aimed to describe the main demographic, clinical, laboratory and therapeutic characteristics and to identify whether they are associated with mortality in tracheostomized patients. MATERIAL AND METHODS.: Retrospective cohort study in adult patients diagnosed with COVID-19, admitted to ICU (Intensive Care Unit) and requiring tracheostomy. Demographic, clinical, laboratory and treatment data were obtained from the medical records of patients admitted to Hospital III Daniel Alcides Carrión in Tacna. The Cox proportional hazards model was used for survival analysis and hazard ratios (HR) with their 95% confidence intervals (95%CI) were calculated. RESULTS.: We evaluated 73 patients, 72.6% were men, the most common comorbidities were obesity (68.5%), type 2 diabetes mellitus (35.6%), and arterial hypertension (34.2%). Thirty-seven percent of the participants died during their stay at the ICU. The median time from intubation to tracheostomy and the duration of tracheostomy was 17 (RIC: 15-21) and 21 (RIC: 3-39) days, respectively. Multivariate analysis showed that the factors associated with mortality were procalcitonin > 0.50 ng/dL at the time of tracheostomy (HRa: 2.40 95%CI: 1.03-5.59) and a PaO2/FiO2 ratio less than or equal to 150 mmHg (HRa: 4.44 95%CI: 1.56-12.60). CONCLUSIONS.: The factors associated with mortality at the time of tracheostomy were procalcitonin > 0.50 ng/dL and a PaO2/FiO2 ratio less than or equal to 150 mmHg.

OBJETIVO.: Describir las principales características demográficas, clínicas, laboratoriales y terapéuticas e identificar si están asociados con la mortalidad en pacientes traqueostomizados. MATERIAL Y MÉTODOS.: Estudio de cohorte retrospectiva en pacientes adultos con diagnóstico de COVID-19, ingresados a UCI (Unidad de Cuidados Intensivos) y que requirieron traqueostomía. Se extrajeron datos demográficos, clínicos, laboratoriales y de tratamiento de las historias clínicas de pacientes que ingresaron al Hospital III Daniel Alcides Carrión de Tacna. Para el análisis de supervivencia se empleó el modelo de riesgos proporcionales de Cox y se calcularon los cocientes de riesgo instantáneos (HR) con sus intervalos de confianza al 95% (IC95%). RESULTADOS.: Se evaluaron 73 pacientes, el 72,6% eran hombres, las comorbilidades más comunes fueron obesidad (68,5%), diabetes mellitus tipo 2 (35,6%) e hipertensión arterial (34,2%). El 37% de los participantes fallecieron durante la estancia en UCI. La mediana de tiempo desde la intubación hasta la traqueostomía y la duración de esta fue 17 (RIC: 15−21) y 21 (RIC: 3−39) días, respectivamente. El análisis multivariado mostró que los factores asociados a mortalidad, fueron presentar un valor de procalcitonina > 0,50 ng/dL en el momento de la traqueostomía (HRa: 2,40 IC95%: 1,03−5,59) y el nivel de PaO2/FiO2 menor o igual a 150 mmHg, (HRa: 4,44 IC95%: 1,56−12,60). CONCLUSIONES.: Los factores asociados a mortalidad al momento de realizar la traqueostomía fueron presentar un valor de procalcitonina > 0,50 ng/dL y un cociente PaO2/FiO2 menor o igual a 150 mmHg.

Unusual Case Report of Synchronous Caecal and Sigmoid Volvulus / Reporte de un caso inusual de presentación sincrónica de vólvulo cecal y de sigmoide

Abstract In the spectrum of patients with intestinal obstruction, volvulus is one of the least frequent etiologies (5-15 %). Synchronous volvulus of two colonic segments in a patient is regarded as rare, with few cases reported in the literature. The present report of synchronous cecal and sigmoid volvulus documents one of them: a patient who underwent subtotal colectomy and formation of ileostomy. Although the preoperative diagnosis of this entity is rare, it should be considered in these intraoperative findings for both intraoperative management, with resection and anastomosis or resection and stoma, and postoperative management. It has a significant impact on mortality if patients are treated with broad-spectrum antibiotic coverage, given the bacterial translocation and sepsis that they experience.

Resumen En el espectro de los pacientes con obstrucción intestinal, el vólvulo es una de las etiologías menos frecuentes, siendo esta del 5 % al 15 %. La presentación sincrónica de dos segmentos colónicos volvulados en el mismo paciente se considera una entidad rara, con pocos casos reportados en la literatura. El presente caso de vólvulo sincrónico del ciego y del sigmoide documenta uno de ellos, en un paciente que se llevó a colectomía subtotal con ileostomía. Aunque el diagnóstico preoperatorio de esta entidad es poco frecuente, se debe tener en cuenta a la hora de encontrarse estos hallazgos intraquirúrgicos para el manejo tanto intraoperatorio, con resección y anastomosis o resección y estoma, como posoperatorios, lo que tiene un impacto importante en la mortalidad, si se manejan los pacientes con cubrimiento antibiótico de amplio espectro, dada la translocación bacteriana y septicemias con los que cursan estos pacientes.

Top, Bottom, and Versatile Orientations among Adolescent Sexual Minority Men.

Sexual role preference or self-label (i.e., top, versatile, or bottom) has been well studied in samples of sexual minority men (SMM) but lacks research among adolescent sexual minority men (ASMM). In response, data were collected from 302 ASMM (15-18 years old), measuring sexual self-label, relationship and sexual experience, sexually explicit media use, use of geosocial networking applications, penis size satisfaction, and gender atypicality. Results showed there was no significant difference in the distribution of sexual position self-identity in ASMM when compared with data from published, adult samples. A model that associated sexual socialization factors with adopting any self-label was significant, with greater number of partners, previous geosocial networking app use, and more relationship experience being positive predictors of having a label. Additionally, a model that tested the convergent validity between self-label and enacted sexual behaviors was significant. Both receptive and insertive sex enactments were highly correlated with corresponding labels. Lastly, gender atypicality and penis size satisfaction were significant predictors of sexual position self-identity. Data from our study supports sexual self-labeling occurring before adulthood, during adolescence for SMM. Furthermore, it shows that socialization factors (e.g., partner frequency, using apps) are important in the development of sexual position self-identity in this population.

The PrEP Cascade in a National Cohort of Adolescent Men Who Have Sex With Men.

BACKGROUND: Pre-exposure prophylaxis (PrEP) has been an available biomedical intervention for at-risk adolescents for over 2 years; however, progression from awareness to uptake and adherence has been slow. In response, we map adolescent men who have sex with men (AMSM) onto the PrEP Motivation Cascade to identify stages for intervention. METHODS: We analyzed PrEP-related attitudinal and behavioral data from a US national cohort of 1398 AMSM. RESULTS: A majority of the sample (53.9%) were identified as appropriate PrEP candidates. Of those identified as appropriate candidates, 51.8% were precontemplative (stage 1; unwilling to take or believing they were inappropriate candidates for PrEP), and 48.2% reached contemplation (stage 2; willing and self-identified as appropriate candidates). Only 16.3% of candidates reached preparation (stage 3; seeing PrEP as accessible and planning to initiate PrEP), and 3.1% reached PrEP action (stage 4; prescribed PrEP). Although few of the AMSM identified as appropriate candidates were on PrEP, most users (87%) reported high adherence to 4+ doses per week (stage 5; PrEP maintenance). Factors associated with reaching later stages were being older, being out to parents, and engaging in previous HIV/sexually transmitted infection testing. CONCLUSIONS: AMSM PrEP use falls short of recommended levels. PrEP campaigns are needed to raise awareness by targeting key AMSM subgroups that underestimate the appropriateness of use. Equally important, parents and health providers of AMSM should serve educational roles to help facilitate potential PrEP uptake, by motivating adolescents and giving them the skills needed to request, fill, and adhere to a prescription.

Bronquiolitis obliterante secundaria a tuberculosis pulmonar / Bronchiolitis obliterans due to pulmonary tuberculosis

La bronquiolitis obliterante es una enfermedad crónica, infrecuente y grave producto de una lesión que afecta fundamentalmente a la pequeña vía aérea. Puede aparecer luego de un trasplante de médula ósea o pulmón, de enfermedades infecciosas o inhalación de humo o vapores tóxicos, o asociada a enfermedades del tejido conectivo. Presentamos el caso de un paciente con un cuadro clínico y funcional, e imágenes, sospechosas de bronquiolitis obliterante posterior a enfermedad pulmonar por Mycobacterium tuberculosis, con respuesta parcial al tratamiento indicado.

Bronchiolitis obliterans is a rare, severe and chronic disease affecting the small airways. It can occur after a bone marrow or lung transplant, infectious diseases, associated with connective tissue diseases or after inhaling smoke or toxic vapors. We report the case of a patient with bronchiolitis obliterans after Mycobacterium tuberculosis pulmonary disease, with partial response to treatment.

Bronquiectasias y anticuerpo anticitoplasma de neutrófilos (ANCA) / Bronchiectasis and antibody neutrophil anticytoplasm (ANCA)

Andrés Ávila: Mujer de 17 años de edad con antecedentes de absceso cerebral, tuberculosis pulmonar a los 9 años, retraso madurativo, infecciones respiratorias a repetición e internación por neumonía grave cuatro meses antes de la consulta sin aislamiento de germen

Three novel variants in the coagulation factor V gene associated with deep venous thrombosis in Chilean patients with Amerindian ethnic background.

BACKGROUND: The activated protein C (APC) resistance is the most common prothrombotic defect in thrombosis patients, mainly related with alterations in the F5 gene. In this work, we evaluated the presence of variants in the FV gene in Amerindian patients with deep venous thrombosis and APC resistance. METHODS: A total of 87 patients with deep venous thrombosis (DVT) confirmed by Doppler ultrasonography, and Amerindian genetic background, were included in this study. APC resistance was assayed by clotting methods and polymorphism F51691G>A was genotyped by molecular methods. In Amerindian patients with APC resistance, the promoter region, exon 7 and exon 10 of the F5 gene were screened by PCR-SSCP and DNA sequencing. The prediction of functional effect of novel mutations was analyzed using Polyphen-2 software. RESULTS: In DVT patients, 14.9% showed functional APC resistance in the absence of F51691G>A polymorphism. Interestingly, three novel missense mutations in exon 10 of F5 gene (M443L, E461Q and G493E) were identified. These genetic variants were absent in 100 healthy subjects. According to in silico analysis, the sequence variants G493E and E461Q are potentially deleterious. CONCLUSIONS: Our data shows that the APC resistance phenotype is not associated with the presence of the F51691G>A variant. We described, for the first time, the presence of three novel variants in F5 gene in Chilean patients with APC resistance. Further studies are required to investigate the real contribution of these novel mutations to the APC resistance phenotype.

Ethanol reduces amyloid aggregation in vitro and prevents toxicity in cell lines.

BACKGROUND: Alzheimer's disease (AD) alters cognitive functions. A mixture of soluble ß-amyloid aggregates (Aß) are known to act as toxic agents. It has been suggested that moderate alcohol intake reduces the development of neurodegenerative diseases, but the molecular mechanisms leading to this type of prevention have been elusive. We show the ethanol effect in the generation of complex Aß in vitro and the impact on the viability of two cell lines. METHODS: The effect of ethanol on the kinetics of ß-amyloid aggregation in vitro was assessed by turbimetry. Soluble- and ethanol-treated ß-amyloid were added to the cell lines HEK and PC-12 to compare their effects on metabolic activity using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. In addition, we used molecular modeling to assess the impact of exposure to ethanol on the structure of ß-amyloid. RESULTS: Exposure to soluble ß-amyloid was toxic to both cell lines; however, exposing the cells to ß-amyloid aggregated in 10 mmol ethanol prevented the effect. In silico modeling suggested that ethanol alters the dynamics for assembling Aß by disrupting a critical salt bridge between residues Asp 23 and Lys 28, required for amyloid dimerization. Thus, ethanol prevented the formation of complex short (∼100 nm) Aß, which are related to higher cell toxicity. CONCLUSIONS: Ethanol prevents the formation of stable Aß dimers in vitro, thus protecting the cells maintained in culture. Accordingly, in silico modelling predicts that soluble ß-amyloid molecules do not form stable multimers when exposed to ethanol.

Neumoencéfalo después de traumatismo craneal / Post-traumatic pneumoencephalus

No disponible

Reverse restriction fragment length polymorphism (RRFLP): A novel technique for genotyping infectious laryngotracheitis virus (ILTV) live attenuated vaccines.

A novel technique, the reverse restriction fragment length polymorphism (RRFLP) assay, was developed as a means of detecting specific informative polymorphic sites in the infectious laryngotracheitis virus (ILTV) genome. During the RRFLP procedure, DNA is digested with restriction enzymes targeting an informative polymorphic site and then used as template in a real-time polymerase chain reaction (PCR) with primers flanking the informative region. The analysis of the DeltaC(t) values obtained from digested and undigested template DNA provides the genotype of the DNA. In this study, the RRFLP assay was applied as a method to differentiate between the two types of infectious laryngotracheitis virus attenuated live vaccines. Sequence analysis of ILTV vaccines revealed an informative polymorphic site in the 5'-non-coding region of the infected cell protein (ICP4) gene. Unique AvaI and AlwI restriction enzyme sites were identified in the tissue culture origin and chicken embryo origin attenuated vaccines, respectively. These two informative polymorphic sites were used in a RRFLP assay to genotype rapidly and reproducibly ILTV attenuated live vaccines.

Pathogenicity and growth characteristics of selected infectious laryngotracheitis virus strains from the United States.

In a recent study, several US infectious laryngotracheitis virus (ILTV) strains and field isolates were genotyped by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) into nine different genotypes. All of the commercial poultry isolates were identified within genotypes IV, V, and VI. Based on the PCR-RFLP, Group IV isolates were characterized as genetically identical to the chicken embryo origin (CEO) vaccines, Group V as genetically closely related to the CEO vaccines, and Group VI as genetically different to the vaccine strains. The objective of this study was to determine the pathogenicity and growth characteristics of six ILTV commercial poultry isolates as compared with the CEO vaccine. Two isolates representative of PCR-RFLP Groups IV, V, and VI were selected. Differences in disease severity, viral tissue distribution in chickens, and plaque formation ability in cell culture were observed among viral genotypes IV, V, and VI, and between V-A and V-B isolates. Mild respiratory clinical signs were produced by IV-A, IV-B and the CEO vaccine, while VI-A and VI-B isolates produced severe respiratory signs and severe depression, and during the peak of clinical signs both isolates were re-isolated from the conjunctiva, sinus, trachea and thymus. Similarly to Group VI isolates, V-A and V-B produced severe respiratory signs, depression, and were re-isolated from conjunctiva, sinus, and trachea; on cell culture, both isolates produced significant larger plaques than any of the other isolates analysed. Overall, differences in pathogenicity and growth characteristics were observed among genetically closely related US ILTV isolates; however, complete genomes will be necessary to identify molecular determinants linked to the pathogenic viral phenotypes.

Evaluation of the protection elicited by direct and indirect exposure to live attenuated infectious laryngotracheitis virus vaccines against a recent challenge strain from the United States.

In a recent study (Oldoni & García, 2007), some field strains of infectious laryngotracheitis viruses (ILTV) were characterized as genotypically different (group VI) from ILT vaccine strains. The objective of this study was to evaluate the protection elicited by one chicken embryo origin (CEO) and one tissue culture origin (TCO) vaccine against a field isolate from group VI after direct and indirect exposure to ILTV live attenuated vaccines. In phase 1 of the experiment, non-vaccinated chickens were placed into contact with the eye drop vaccinates for a period of four weeks after vaccination. Transmission of the vaccine virus to these in-contact birds was demonstrated by real time PCR and antibody production, although the in-contact birds did not become protected against disease when subsequently challenged in phase 2 of the experiment. This emphasized the importance of uniform vaccination to obtain adequate protection, both to avoid the occurrence of susceptible chickens, and to minimize the potential for reversion to virulence of live-attenuated vaccines. In phase 2, protection against challenge with a group VI field virus was assessed four weeks after vaccination by scoring clinical signs and mortality, and quantifying weight gain. Sentinel birds were added to the groups one day after challenge to assess shedding of challenge virus, using real time PCR and virus isolation, during the period 2 to 12 days post challenge. The results showed that the CEO and TCO eye drop-vaccinated chickens were protected against challenge with the group VI virus, even though it was genetically different from the vaccine strains, and that challenge virus was not transmitted from these protected birds to the sentinels.