Dear colleagues, With respect to the degree of seroconversion, surely what matters is whether the immune response is sufficient for protection, not how high the VNT titre is? We have a tendency to focus on the measurable antibody titre, but I want to point out again that it has never been shown that it is serum antibody that is protective. It could be the (much more difficult to measure) T cell immunity. The OIE manual only says that a PPRV vaccine has to give a VNT titre of 1:10 because we know from experience that an effective PPRV vaccine will give such a titre, not that such a titre is protective. For those not familiar with the old RPV literature, it was shown that recombinant poxviruses that gave no detectable anti-RPV antibody were still protective. Yilma et al made recombinant RPV glycoproteins, injected them into cattle, and got nice antibody responses - but no protection. The difference between sheep and goats may be in the balance of immune responses; as Dr Singh has just posted, PPRV may replicate a bit better in goats, and so elicit a higher immune antibody response. The only thing that counts, in the end, is whether the animal is protected. best wishes Michael Michael D Baron PhD Group Leader, Paramyxo&Bunyaviruses t +44 (0) 1483 231024/1072/1145 email [log in to unmask]<mailto:[log in to unmask]> http://www.pirbright.ac.uk/research/Paramyxo/Default.aspx<http://www.iah.ac.uk/research/Paramyxo/Default.aspx> Preventing and controlling viral diseases The Pirbright Institute, Ash Road, Pirbright, Woking, Surrey GU24 0NF t +44 (0)1483 232441 f +44 (0)1483 232448 e [log in to unmask] A company limited by guarantee, registered in England no. 559784. The Institute is also a registered charity. Director: Professor John Fazakerley BSc, MBA, PhD, FSB, FRCPath. The Pirbright Institute receives strategic funding from the Biotechnology and Biological Sciences Research Council. From: Establishment of a PPR Global Research and Expertise Network (PPR-GREN) [mailto:[log in to unmask]] On Behalf Of Paul Rossiter Sent: 07 February 2014 15:59 To: [log in to unmask] Subject: From Dr Srinivasan on the possible need for species specific vaccines Dear Colleagues, When we first developed PPR Sungri/96 vaccine, during the initial field evaluation of vaccine we observed goats were better sero-converters than Sheep. In a study involving more than 500 post-vaccinate sera samples in each of the species, we observed 98% sero-conversion in goats and 83% in sheep. Even the VN titer was lesser in sheep than goats (eg., most of the goats had 1:64 to 1:128 and sheep it was 1:32 to 1:64). PPR Sungri/96 virus which was used to develop attenuated vaccine was originally rescued from post-mortem samples from a goat died in the PPR outbreak. Does this suggests that we should have separate vaccine candidates for sheep and goat? I must confess I am not keeping abreast of PPR literature as I have moved away from PPR research almost 11 years back. Regards Srinivas I hope that several of you will give us your views on this radical idea - moderator ________________________________ Dr.B.P.Srinivas Principal Scientist Indian Veterinary Research Institute (IVRI) Hebbal, Bangalore-560024 India Tel: 91-80-23410729 (Work) Fax: 91-80-23412509 ________________________________ To unsubscribe from the FAO-AnimalHealth-L list, click the following link: https://listserv.fao.org/cgi-bin/wa?SUBED1=FAO-AnimalHealth-L&A=1 ________________________________ The information contained in this message may be confidential or legally privileged and is intended solely for the addressee. If you have received this message in error please delete it & notify the originator immediately. Unauthorised use, disclosure, copying or alteration of this message is forbidden & may be unlawful. The contents of this e-mail are the views of the sender and do not necessarily represent the views of the Institute. This email and associated attachments has been checked locally for viruses but we can accept no responsibility once it has left our systems. Communications on Institute computers are monitored to secure the effective operation of the systems and for other lawful purposes. The Pirbright Institute is a company limited by guarantee, registered in England no. 559784. The Institute is also a registered charity. ######################################################################## To unsubscribe from the FAO-AnimalHealth-L list, click the following link: https://listserv.fao.org/cgi-bin/wa?SUBED1=FAO-AnimalHealth-L&A=1