- Tissue culture cells, laboratory animals and embryonated chicken eggs were known to be the methods for viral isolation.
- Specific pathogen free-embryonated chicken eggs (SPF- ECE) became the most suitable, specific and sensitive vivo for viral isolation due to cell cultures (primary, secondary or established cell lines) and sera of human or animal origin often being latently infected with a herpes virus (Epstein – Barr virus or ovine herpesvirus – 2) which is highly prevalent and ubiquitous where the failure of isolation was noticed in the last few years and cytopathic effect (CPE) was detected in non inoculated (controls) cell cultures. Also, laboratory animals are susceptible to herpes virus infections, hence they became having latency and their use for viral isolation, in general, is inaccurate.
- Herpesvirus can be isolated accurately in SPF–ECE via the yolk sac route (6 – 8 days old embryos) and chorioallantoic membrane route (10 – 12 days old embryos) .
- N.B: We must take into our consideration that viral propagation for any vaccine production can be successfully performed with a suitable route of SPF – ECE to avoid latency in cells of tissue cultures or positive sera used for media preparation.
References:
- Bastawecy, M. Iman (2021): Mode of infection and some diseases caused by Epstein Barr virus: The most ubiquitous, common, malignant, and characteristic virus. H Hum Virol Retrovirology, 9 (1): 6 – 9 .
- Bastawecy , M . Iman; Zaki , A. A. ; Sobhy , N . M. (2014) : Ovine herpesvirus 2 infection causes sudden death and abortion in susceptible animals . Life Science Journal, 11 ( 10 ) : 957 – 964 .
- Blood, D. C.; O . M. Radostits ; J . A. Henderson (1983): Veterinary Medicine, six edition.
- Burleson, F. G.; T . M. Chambers; D. L. Wiedbrauk (1992): Virology, Laboratory Manual .
- Versteeg, J.(1990) : A colour Atlas of Virology . Wolfe Medical Publications Ltd , London , England .
I think the best method (simpler and more economical) is innoculation by the chorioallantoic membrane route (09 – 12 days old embryos). this route is also more sensitive than innoculation the yolk sac route.
CAM route is the best becase we can identify the pocks easily but YS route is at younger age and the effect of the herpes virus is on the embryo directly .
Question isolation of herpes virus,so it depend on kind of herpes virus group and it,s tropism to kind of tissue e.g avian herpes virus best tissue for tropism and isolation is CAM of SPF embryonated chick while Bovine herpes virus best tissue for isolation is Bovine teste,s and secondary tissue culture while Equine tissue for isolation is coninuous cell line.so tropism and affinity for tissue determine kind tissue used for isolation.
Best regards
All herpesviruses can be isolated in SPF - ECE and it is know the most accurate and sensetive method because allcell cultures now are have latency with the most prevalent herpesvirus and also laboratory animals are highly susceptible to herpesvirus .
Latency is not for herpesvirus only ,question is isolation of herpesvirus.So selective tissue for isolation must be specfic according to tropism of virus and affinity to tissue culture,question focus on iolation of herpesvirus ,Avian herpes,Bovine herpes,Equine herpes,ovine herpes.for isolation purpose diavnostic,vaccine production....so.....on.
Different tissue cultures are now not as before and if you try isolatoion now , you found cells of controls showed something variable , so SPF- ECE is the most propable furtionately .The most common lknown virus joined to latency is herpesvirus because it has gens for facilitating this property , to make its DNA teaser to genome of the host .
Colleaque CAM ,TISSUE CULTURE ,CONTNUOUS CELL LINE .......in past and recently the cheapest available tool for herpes virus isolation and vaccine production ,PCR is recent rapid tool for diagnosis.finally i say tissue culture till used but molecular aid used for specifity and rapid but coast
My work since 1988 was isolation in primary , secondary and established cell lines , inaddition to laboratory animals . Now , tissue cultures became unsuitable and also lab animals this is not only my experience and notice but also more colleages .
There are enormous no of techniques are available for cultivation of Virus in vitro and in Vivo. As an animal virus its genetic material may be RNA or DNA so depend upon that we can choose method for cultivation. Fertilized egg Inoculation method is for Vaccine development especially for Poultry Vaccines.
Not any fertilized eggs can be used but SPF - ECE to be sure that it is free from any pathogen and you will find that it must be used for vaccine and isolation due to cell cultures now has aproblem and in the past , fertilized eggs can be used also for vaccine preparation , not only for poultry but also for others such as small pox .
SPF embryonated eggs used for vaccine production either for human or animals irrespective for purpose , .also used for the aim of diagnosis of viral diseases and chlamydia ......lots of purpoes can be considered.
Best regards
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