The cytokine response of afferent lymph following orf virus reinfection of sheep

Abstract The in vivo dynamics of differentiated cells and interleukin (IL)-lβ, IL-8, granulocyte-macrophage colony-stimulating factor (GM-CSF) and interferon (IFN)-γ titres in afferent lymph were compared following orf virus reinfection and inactivated virus injection of previously infected sheep. The biphasic lymphoblast and cytokine response in the lymph to virus reinfection is consistent with a response initially to orf virus as recall antigen followed by a response to viral replication. CD4 T cells increased in output over other cell types in the lymph in both groups. A rapid immune/inflammatory response was detected in lymph plasma as an increase in cytokine titres within 24 h of virus reinfection or injection. Lymph cells producing IL-1β and IL-8 appeared prior to those producing GM-CSF in both groups. In spite of variations in the concentration of individual cytokines in lymph following reinfection, both the size of the orf lesion and the time to resolve were similar in all cases. Résumé— Les dynamiques in vivo des cellules différenciées et des taux d'IL-1β, de GM-CSF et d'interferon γ dans la lymphe afférente furent comparés chez des moutons antéricurement infectés après une réinfection par le virus de l'ecthyma contagieux et après injection d'un virus inactivé. La réponse biphasique lymphoblastique et des cytokines à la réinfection virale est compatibles avec une réponse primaire au virus de l'ecthyma contagieux comme antigène mémoire suivie par une réponse secondaire à la réplication virale. Dans les 2 groupes, le nombre de TCD4 est plus élevé que les autres populations cellulaires mises en évidence dans la lymphe. Une réponse de type immune/inflammatoire est révélée dans le plasma par une élévation des taux de cytokines dans les 24 heures qui suivent la réinfection virale ou l'injection de virus inactivé. Les lymphocytes producteurs dTL-1β et d'IL-8 apparaissent avant les lymphocytes producteurs de GM-CSF dans les deux groupes. En dépit des variations de concentration des cytokines individuelles dans le lymphe après reinfection, à la fois la taille des lesions d'ecthyma et les délais de guérison sont identiques dans tous les cas. [Haig, D., Deane, D., Percival, A., Myatt, N., Thomson, J., Inglis, L., Rothel, J., Heng-Fong Seow, Wood, P., Miller, H. R. P., Reid, H. W. The cytokine response of afferent lymph following orf virus reinfection of sheep (Effet sur les cytokines de la lymphe afferente d'une reinfection par les virus de l'ecthyma contagieux chez le mouton.) Veterinary Dermatology 1996; 7 : 11–20.] Resumen Se comparó la actividad de células diferenciadas y los titulos de interleuquina (IL)-1β, IL-8, factor de estimulación de colonias de granulocitos y macrófagos (GM-CSF) e interferon (IFN)-y entre reinfecciones por el virus del ectima contagioso e inyección de virus inactivado de ovinos previamente infectados. La respuesta a la reinfección en forma bifásica linfoblástica y de citoquinas en la linfa está de acuerdo con una respuesta inicial al virus del ectima por estimulación antigénica, seguida por una respuesta a la replicación viral. Las células T CD4 aumentaron respecto a otros tipos celulares en la linfa de ambos grupos. Se detectó una respuesta inmune/inflamatoria rápida en el linfa-plasma en forma de aumento de los titulos de citoquinas dentro de las 24 h de reinfección o inyección del virus. Las células linfáticas productoras de IL-1β e IL-8 aparecicron antes que las productoras de GM-CSF en ambos grupos. A pesar de las variaciones en la concentración de citoquinas individuates en la linfa después de la reinfección, tanto el tamaño de la lesión por el virus del ectima contagioso como el tiempo de resolución fueron similares en todos los casos. [Haig, D., Deane, D., Percival, A., Myatt, N., Thomson, J., Inglis, L., Rothel, J., Heng-Fong Seow, Wood, P., Miller, H. R. P., Reid, H. W. The cytokine response of afferent lymph following orf virus reinfection of sheep (Produccion de citoquinas en el ganglio linfatico afferente tras la reinfección por el virus del ectima contagioso.) Veterinary Dermatology 1996; 7 : 11–20.] Zusammenfassung— Es wurde die in-vivo-Dynamik der Titer differenzierter Zellen und Interleukin (1L)-1β, IL-8, Granulozytenmakrophagenkolonien-stimulierender Faktor (GM-CSF) und Interferon (IFN)-γ in afferenter Lymphe nach einer Reinfektion mit ORF-Virus und einer Injektion inaktivierten Virusmaterials von früher infizierten Schafen verglichen. Die biphasische Lymphoblasten- und Zytokin-Reaktion in der Lymphe auf die Virusreinfektion stimmte mit einer initialen Reaktion gegenüber ORF-Virus überein, da der Wiederabruf von Antigen von einer Reaktion auf die Virusreplikation gefolgt wird. CD4-T-Zellen vermehrten sich im Output stärker als andere Zelltypen in der Lymphe beider Gruppen. Es wurde eine rasche immunologische/entzündliche Reaktion im Lymphplasma in Form eines Anstieges von Zytokin-Titern innerhalb von 24 Stunden nach Virusreinfektion oder -injektion festgestellt. Lymphatische Zellen, die IL-1β und IL-8 produzieren, erschienen vor dem Auftreten von solchen, die GM-CSF produzieren, in beiden Gruppen. Trotz des Schwankens der Konzentration der individuellen Zytokine in der Lymphe nach Reinfektion, waren sowohl die Größe der ORF-Veränderungen und die Zeit der Heilung ähnlich in alien Fällen. [Haig, D., Deane, D., Percival, A., Myatt, N., Thomson, J., Inglis, L., Rothel, J., Heng-Fong Seow, Wood, P., Miller, H. R. P., Reid, H. W. The cytokine response of afferent lymph following orf virus reinfection of sheep (Die ZytokinReaktion afferenter Lymphe nach einer Reinfektion mit orf-virus beim schaf.) Veterinary Dermatology 1996; 7 : 11–20.]     

Vaccination of sheep

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SIR,—It has been mentioned to me that some veterinary surgeons are ,not happy with the latest recommendations for the vaccination of sheep—that is, in the neck instead of behind the shoulder site as previous1y.     

The response of the supramammary lymph node of the sheep to secondary infection with orf virus

The response of the supramammary lymph node of seven sheep to secondary infection with orf virus was examined by cannulating the efferent lymphatic before infecting the drainage area of the node. All animals developed typical orf lesions and responded after an initial lag period with an increase in total cell output paralleled by a rising proportion of lymphoblast cells. Most lymphoblast contained immunoglobulin with a predominance of the IgG class. When cultured, these cells produced measurable amounts of virus-specific antibody. The proportion of cells which stained with a T-cell-specific monoclonal antibody was measured in two of the sheep and found to decrease as the response developed. These data suggest that the nodal response is directed mainly towards the production of virus-specific antibody. The extent of T-cell involvement remains unclear.     

Response of efferent lymph and popliteal lymph node to epidermal infection of sheep with orf virus

Functional and phenotypic changes in the cell populations were monitored in the popliteal efferent lymph of sheep following experimental epidermal infection with orf virus. In another group of sheep, cells from the popliteal lymph node draining the site of infection were similarly monitored and compared with the cells from contralateral popliteal and mesenteric lymph nodes. All sheep showed serological evidence of previous exposure to orf virus. Following infection, anti-orf antibody titres rose and efferent lymphocyte and blast cell output increased. Interferon-like activity was detected in efferent lymph early after orf virus but not mock infection. Lymphocytes from the draining popliteal lymph node showed antigen-specific lymphoproliferation on Days 3-7 while cells in the efferent lymph demonstrated proliferative activity on Days 4-6. The requirement for exogenous antigen-presenting cells in the culture of efferent lymphocytes varied between individual sheep. The culture supernatant from proliferating lymph node cells contained interferon-like activity but no anti-orf antibodies, the reverse of that from cultured efferent lymphocytes, perhaps indicating a different reactive T cell population. During the course of the experiment there was an increase in the percentage of efferent lymphocytes expressing MHC Class II antigens and surface immunoglobulins, the latter being recorded as a double peak. The short-term nature of the local T cell response may in part explain the incompleteness of immunity to orf virus in sheep.     

Culture of sheep Chlamydia in a sheep fibroblast cell culture.

Abortion and enteric isolates of Chlamydia psittaci from sheep differed in their growth in a fibroblastic cell culture derived from the small intestine of a lamb. Twenty abortion isolates, each from a different farm, produced large inclusions which could be passaged several times whereas 10 enteric isolates each from different farms (but from some of the farms of origin of the abortion isolates) produced sparse inclusions which could not be passaged. This appears to be a rapid method of distinguishing abortion and enteric isolates and may indicate different nutritional requirements or be related to the invasiveness of the isolates.     

A qualitative and quantitative assessment of the humoral antibody response of the sheep to orf virus infection

The serological response of naturally and experimentally infected lambs to orf virus infection was analysed using an enzyme-linked immunosorbent assay (ELISA) together with the Western blotting technique. The combination of these two methods permitted a qualitative and quantitative assessment of the response, which revealed considerable variation between animals. Despite this, all post-exposure sera reacted with a polypeptide (molecular weight 40 kilodaltons) which appears to be a component of the surface tubules that are characteristic of the virus.     

Vaccination of sheep against Aujeszky's disease with a gI-deleted mutant]

The use of gl deleted live vaccines against Aujeszky's disease (AD) facilitates to differentiate vaccinated from field-virus infected animals. In this study different modes of vaccination were tried to find out how sheep can be protected from a lethal infection with ADV. It could clearly be demonstrated that Aujeszky disease virus (ADV) is spread by horizontal transmission from infected pigs to sheep. The nasal discharges of infected pigs contained a maximum of 10(8.75)TCID50/g mucus at days 3 and 4 p.i. and those of the contact-pigs 10(8.5)TCID50/g mucus at days 6 and 7 after contact. Non-vaccinated contact sheep were infected horizontally by the pigs. The highest titres ranged from 10(6.25) to 10(7.5)TCID50/g mucus. These animals were sacrificed at day 5 p.i. exhibiting acute symptoms of AD. The nasal discharge of vaccinated sheep contained much lower amounts of ADV (maximum: 10(4.25)TCID50/g mucus). All surviving animals had developed antibodies. Following challenge with the ADV-strain NIA3, no febrile response or virus-shedding was observed in sheep vaccinated 2x s.c. or 2x i.m. with a gl deleted live vaccine, whereas sheep, vaccinated only 1x i.m. (4 out of 4 animals) or 1x i.m. (3 out of 4 animals) or 1x i.n. and 1x i.m. (1 out of 4 animals) had to be sacrificed after showing acute symptoms of AD. In conclusion it can be stated that a double parental vaccination with a gl deleted live vaccine protects sheep against a field-virus AD infection.     

Molecular characterization of Brazilian isolates of orf virus

Outbreaks of an epidermic disease suggesting parapox virus infections have been observed in all major herds of sheep and goats from different geographical areas of Brazil. Clinical samples (dried scabs) were collected and orf virus was isolated and characterized by electron microscopy in previous work. In order to characterize these viruses at the molecular level, a modified methodology for genomic DNA extraction directly from scabs was used and such DNA was used to derive the restriction enzyme digestion patterns for clinical samples from three distinct geographic origins. Pulsed field gel electrophoresis was used to separate restriction enzyme DNA fragments and heterogeneity among isolates from different geographic areas could be observed on stained gels. The HindIII-G DNA fragment from orf-A virus genome was cloned and hybridized to DNA of other orf virus isolates. Further heterogeneity was confirmed by these hybridizations.     

Vaccination against Brucella ovis infection in sheep

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Dairy cows in New Zealand subsist chiefly on pasture or pasture products such as hay and silage, whilst concentrates are fed only in exceptional cases. Town supply herds are concerned with the production of winter milk and payment by the dairy factory is based on their milk production assessment during the months of June, July, and August. It is therefore necessary to have maximum milk production during these winter months when pastures are at their minimum rate of growth. As a food supplement, therefore, many town supply herds augment their feeding with crops and wet brewers' grains. The grains are fed from hoppers in the bail and are also spread out in the paddocks or placed in large wooden troughs. Most grains are purchased on a contract basis from the brewers, more being available during the summer months, when more beer is consumed. Friday's load of grains is usually stored and the consumption spread out over the week-end until the first fresh load is brought in on Monday morning.