ORIGINAL ARTICLE Molecular characterization of Brucella melitensis Rev.1 strain in aborted sheep and goats in Iran Abolfazl Saeedzadeh & Hassan Sharifiyazdi & Roya Firouzi Received: 30 May 2011 / Accepted: 17 January 2012 / Published online: 11 February 2012 # Springer-Verlag London Limited 2012 Abstract Live attenuated Brucella melitensis Rev.1 strain is currently used in some countries against caprine and ovine brucellosis. Although live B. melitensis Rev.1 strain is considered the best vaccine available for the prophylaxis of brucellosis in sheep and goats, its residual abortifacient potential in pregnant animals is still a problem. We used a specific PCR–RFLP method to distinguish B. melitensis Rev.1 from other Brucella field isolates derived from aborted fetuses of sheep and goats in Iran. Molecular typing of 46 Brucella spp. isolates revealed that five strains were B. melitensis Rev.1 vaccine strain. Keywords Brucella melitensis Rev.1 . Brucella melitensis . Iran . Aborted fetuses Introduction Brucellosis is endemic in Iran and many parts of the world and remains one of the major diseases in humans and domesticated animals. It emerged as a disease with the discovery of Brucella melitensis by Bruce in 1887 (Corbel 1997). Despite numerous biotechnological improvements, brucellosis remains a major worldwide zoonosis (Cutler et al. 2005). In humans, ovine/caprine, brucellosis caused by B. melitensis is by far the most important clinically apparent disease (Corbel 1997). B. melitensis is one of the major causes of abortion in sheep and goats, and the organism is secreted in the milk of infected animals (Bardenstein et al. 2002). Prevention of human brucellosis depends on the control of the disease in animals (Corbel 1997). Eradication of brucellosis has been a goal for many countries, with success in several countries in northern Europe, but it still remains a major problem in the Mediterranean region, western Asia, and parts of Africa and Latin America. Those countries that have managed to eradicate the infection cannot afford to be complacent as the threat of reintroduction is ever present through the move- ment of livestock (Cutler et al. 2005). Brucellosis control and eradication require serological tests and vaccines (Moriyón et al. 2004). It is generally agreed that under most conditions, B. melitensis cannot be eradicated by testing and slaughtering alone, and a vaccination program has to be applied to reduce the spread of the disease (World Health Organization 1998). The discovery of live B. melitensis Rev.1 vaccine (Elberg and Faunce 1957) has been of para- mount importance in the control of brucellosis in small rumi- nants in many countries (Blasco 1997). Live attenuated B. melitensis Rev.1 strain has, until recently, been considered the best vaccine available for prophylaxis of B. melitensis infec- tion in small ruminants (Bardenstein et al. 2002). However, Rev.1 shows some undesirable traits: it is infectious for humans, may be abortifacient when used in pregnant animals, and can induce an immune response that may be difficult to distinguish from that resulting from infection, particularly when adult animals are vaccinated (Moriyón et al. 2004). Moreover, vaccination does not always protect the animals in the field and several cases of secretion of the field strain in milk have proven the inefficacy of the whole vaccination program (Bardenstein et al. 2002). A. Saeedzadeh : R. Firouzi (*) Department of Pathobiology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran e-mail: royfirouzi@yahoo.com H. Sharifiyazdi Department of Clinical Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran Comp Clin Pathol (2013) 22:409–412 DOI 10.1007/s00580-012-1424-7