Anatomopathological and molecular studies of Marek's disease virus in India

In India, increasing incidence of Mareks Disease Virus (MDV) outbreaks are being reported even in vaccinated poultry farms. Hence identifying the new emerging pathotype of MDV is necessary for successful control through vaccination. Birds received in the post mortem section of The Avian Disease Laboratory, Indian Veterinary Research Institute, were screened for the presence of MDV by collecting neoplastic tissues, spleen and feather follicles. Screening was carried out by polymerase chain reaction (PCR) and histopathological examination. Among the tested 150 birds tissue samples, 35 bird tissue samples were found positive for MDV. Based on pathotyping specific PCR, it was found that 34 birds tissues were affected virulent MDV and one birds tissue was affected with very virulent MDV. Since, HVT vaccine will not protect the very virulent pathotype, combined vaccine of SB-1 and HVT can be administered to control the very virulent MDV. Among the MD infected birds, neoplastic liver is most commonly encountered. Spleen tissue samples was found to be more suitable for the DNA isolation for PCR.(AU)

Anatomopathological and molecular studies of Marek's disease virus in India

In India, increasing incidence of Marek’s Disease Virus (MDV) outbreaks are being reported even in vaccinated poultry farms. Hence identifying the new emerging pathotype of MDV is necessary for successful control through vaccination. Birds received in the post mortem section of The Avian Disease Laboratory, Indian Veterinary Research Institute, were screened for the presence of MDV by collecting neoplastic tissues, spleen and feather follicles. Screening was carried out by polymerase chain reaction (PCR) and histopathological examination. Among the tested 150 birds’ tissue samples, 35 bird tissue samples were found positive for MDV. Based on pathotyping specific PCR, it was found that 34 birds tissues were affected virulent MDV and one birds tissue was affected with very virulent MDV. Since, HVT vaccine will not protect the very virulent pathotype, combined vaccine of SB-1 and HVT can be administered to control the very virulent MDV. Among the MD infected birds, neoplastic liver is most commonly encountered. Spleen tissue samples was found to be more suitable for the DNA isolation for PCR.

Outbreak of infectious laryngotracheitis in large multi-age egg layer chicken flocks in Minas Gerais, Brazil / Surto de laringotraqueíte infecciosa em granjas de galinhas poedeiras de múltiplas idades em Minas Gerais, Brasil

A recent (November 2010) outbreak of infectious laryngotracheitis (ILT) in a multi-age laying hen facility in Minas Gerais state, Brazil, is described. Previous ILT outbreak in laying hens was only notified in São Paulo state, Brazil, in 2002. In the outbreak described here, the affected population was approximately eight million hens, with flock sizes ranging from 100,000 to 2,900,000 chickens. The average mortality ranged from 1 to 6%, and morbidity was around 90% (most of the twenty seven farms of the area were positive for ILT virus). Three multi-age laying farms from one company were selected for this report. Clinical signs included prostration, dyspnea, conjunctivitis, occasional swelling of the paranasal sinuses and bloody mucous nasal discharge. Severely affected chickens presented with dyspnea, gasping and became cyanotic before death. At necropsy, these chickens had fibrinous exudate blocking the larynx and the lumen of cranial part of the trachea. In addition, conjunctivitis with intense hyperemia, edema and sinuses with caseous exudate were present. On histopathology, there were marked necrosis and desquamation of respiratory ephitelium and conjunctiva with numerous syncytial cells formation and fibrinous exudate. Moderate to marked non suppurative (especially lymphocytes and plasma cells) infiltration in the lamina propria also was observed. Sixteen out of 20 examined chickens, eosinophilic intranuclear inclusion bodies were observed in the syncytial cells. The DNA extracted from larynx and trachea produced positive PCR results for ILT virus (ILTV) DNA using formalin-fixed, paraffin embedded (FFPE) samples. Amplicons from a small region of ICP4 gene were submitted to sequencing and showed 100% identity with ILTV EU104910.1 (USA strain), 99% with ILTV JN596963.1 (Australian strain) and 91% with ILTV JN580316.1 (Gallid herpesvirus 1 CEO vaccine strain) and JN580315.1 (Gallid herpesvirus 1 TCO vaccine strain).(AU)

Um surto recente (Novembro de 2010) de laringotraqueite infecciosa (LTI) em granjas de postura de múltiplas idades em Minas Gerais, Brasil, é descrito. Um surto de LTI em galinhas de postura havia sido previamente relatado apenas no Estado de São Paulo em 2002. No surto aqui descrito, a população afetada foi de aproximadamente oito milhões de galinhas, com lotes variando de 100.000 a 2.900.000 galinhas. A mortalidade média variou de 1 a 6% e a morbidade atingiu cerca de 90% (a maioria das 27 granjas foram positivas para o virus da LTI). Três granjas com aves de múltiplas idades pertencentes a uma empresa foram selecionadas para o presente relato. Os sinais clinicos incluíram prostração, dispneia, conjuntivite, edema ocasional dos seios paranasais e secreção nasal mucosa e/ou sanguinolenta. As aves severamente afetadas apresentaram acentuada dispneia, aparente engasgo e tornaram-se cianóticas antes da morte. Nestas aves, exsudato fibrinoso denso obstruindo o lúmen da laringe e parte cranial da traqueia foi observado na necropsia. Havia também, conjuntivite com hiperemia intensa e edema, além de sinusite com exsudato caseoso. Na histopatologia, observaram-se necrose e descamação acentuada do epitélio respiratório e da conjuntiva com formação de numerosos sincícios e exsudato fibrinoso. Além disso, infiltrado inflamatório mononuclear (especialmente linfócitos e plasmócitos) moderado a acentuado na lâmina própria foi observado. Corpúsculos de inclusão intranucleares nas células sinciciais foram observados em 16 das 20 aves examinadas. Resultados positivos pela PCR para o virus da LTI foram obtidos de DNA extraído das laringes e traqueias utilizando amostras fixadas em formol e incluidas na parafina. O produto amplificado de uma região pequena do gen ICP4 foi submetido ao sequenciamento e quando comparado com outras sequências depositadas no Genbank mostrou os seguintes resultados: 100% de identidade com uma estirpe do virus de LTI dos Estados Unidos (JN596963.1), 99% de identidade com uma estirpe Australiana e 91% com a estirpe vacinal CEO (JN580316.1) e TCO (JN580315.1).(AU)