【病毒外文文獻(xiàn)】2005 Proposal for vaccination against SARS coronavirus using avian infectious bronchitis virus strain H from The Netherl

Occult hepatitis B virus infection among anti HBc should be adopted by all the blood banks in order to in group 4 is highly contagious and treatment of infected persons has so far been disappointing Letters to the Editor 263 positive blood donors Necessitates substitution of screening by HBV NAT Safe blood transfusion still remains a major concern and so far all the efforts in this direction have failed to achieve zero residual risk of transfusion trans mitted hepatitis B virus HBV infection In this direction the recently published work by Silva et al in Journal of Infection has revealed remarkable observations 1 This report shows 3 3 HBV DNA positivity of the blood donor s samples that were anti HBc positive more enlightening finding is the HBV DNA positivity among the high level anti HBs positive donors At this tertiary care centre of Saudi Arabia out of 26 606 blood units collected during 2000 2003 isolated anti HBc positivity was 3 2 and HBsAg positivity 1 9 where as 10 1 of the blood units were anti HBc and anti HBs positive As per policy of health ministry the anti HBc and anti HBs positive blood units were utilized and the isolated anti HBc blood units were rejected 2 The blood units which are anti HBc and anti HBs positive do not appear to transmit HBV infection and there is inverse correlation between anti HBs level and infectivity only 10 of the blood units with low level 0 1 IU ml anti HBs are infectious 3 The observation by Silva et al that HBV DNA positivity amonganti HBcandhighlevelanti HBs positiveblood donors is a pointer towards the transfusion trans mitted risk involved by transfusion of anti HBc and anti HBs positive blood units Though the viral load in these samples was low 1000 copies ml but this can be highly infectious if transfused to an immuno comprised patient Considering the volume of infectious blood transfused any amount of HBV DNA will be infectious as the minimum infecting dose of HBV in chimpanzees is only 100 virus particles 4 In many of the developed countries and most of the developing countries the blood units collected are still being screened for HBsAg anti HBc and anti HBs by enzyme immuno assay On many occasions the results are indeterminate and has to be repeated leading to higher per unit cost of blood screening and lot of rejection of the invaluable units of collected blood or exclusion of the generous donor because of isolated anti HBc positivity and still the safety of transfusion transmitted HBV is compromised This high rate of rejection of collected blood units and the exclusion of the anti HBc positive blood donors leads to the unceasing blood shortage in the blood banks The HBV screening policy for the collected units of blood needs reassessment in light of the present report 1 and HBV DNA testing should be preferred instead of three enzyme immuno assay tests HBV DNA testing by NAT of all the collected units of blood The first evidence of successful treatment in monkeys cynomolgus macaques was reported recently using alpha interferon IFN alpha 4 admi nistered from 1 to 3 days after experimental possibly achieve zero risk of transfusion transmitted HBV infection and also to reduce the rejection rate of the precious units of collected blood by testing for anti HBc References 1 Silva CMD Costi C Costa C et al Low rate of occult hepatitis B virus infection among anti HBc positive blood donors living in a low prevalence region in Brazil J Infect 2005 51 24 9 2 Panhotra BR Bahrani A Hassan ZU Epidemiology of antibody to hepatitis B core antigen screening among blood donors in Eastern Saudi Arabia Need to replace the test by HBV DNA testing Saudi Med J 2005 26 270 3 3 Allain JP Occult hepatitis B virus infection Implications in transfusion Vox Sang 2004 86 83 91 4 Price AM Stephan W Brotman B b Propiolactone irradiation A review of its effectiveness for inactivation of viruses in blood derivatives Rev Infect Dis 1983 5 92 107 B R Panhotra A Bahrani C S Joshi Zahoor ul Hassan Laboratory and Blood Bank King Fahad Hospital Al Hofuf Al Hasa 31982 Saudi Arabia E mail addresses drpanhotra2000 yahoo co in drpanhotra30 Accepted 23 February 2005 Corresponding author Tel C966 3 5750000 1768 Q 2005 The British Infection Society Published by Elsevier Ltd All rights reserved doi 10 1016 j jinf 2005 07 023 Proposal for vaccination against SARS coronavirus using avian infectious bronchitis virus strain H from The Netherlands The outbreak of severe acute respiratory syndrome SARS in 2003 has resulted in a number of infections and deaths among healthcare workers HCWs and those in contact with SARS infected persons The virus now classified provisionally as a coronavirus exposure This gave only some success whereas the a It is proposed to use passage 52 of the H strain Letters to the Editor264 drug given at 3 days before experimental infection significantly reduced viral replication and excretion from their throats Lung damage was also reduced by 80 as compared with non treated monkeys In a review article on avian infectious bronchitis IB vaccine strain H 1 various characteristics of this vaccine were outlined Here I shall mention the most valuable properties of this IB vaccine so far known to underline the hypothesis that it may be beneficial in people at risk from SARS coronavirus 1 It has been observed that the IB vaccine H is able to protect against a broad spectrum of different heterologous serotypes of IB challenge viruses 12 These serotypes differ in their surface proteins spikes S1 which are responsible for the induction of neutralizing antibody Differ ences in S1 of only 2 3 can change the serotype of an IB virus 3 Therefore it can be concluded that the protection provided by the vaccine strain H is not only dependant on the production of neutralizing antibody but is also due to the induction of other immunological reactions 2 The role of the nucleocapsid protein N is still not well understood but it may play an important role in protection inducing specific cytotoxic T lymphocytes 2 7 10 Thus the vac cine strain H may be responsible for the induction of protection through its nucleocap sid protein 13 In order to evaluate the import ance of cellular mediated immunity CMI in protecting against IBV infections more studies would be necessary to explain all the mechan isms of cross protection of the vaccine strain H for instance the induction of interleukine 2 IL 2 3 The observation that interferon IF is poorly induced by IBV and may not be induced by the vaccine strain at passage level 52 could be an indication that IF plays a limited role in heterologous protection 5 4 In a study by Marra et al 6 it was concluded that the SARS coronavirus is a novel coronavirus Stavrinides and Guttman 11 concluded recently that the SARS coronavirus is mammalian like through the replicase protein and avian like through the M and N proteins They also observed a mammalian avian mosaic in the S protein These observations are of extreme importance to the consideration of an avian coronavirus as a possible candidate for a vaccine against SARS coronavirus In adequately equipped laboratory facilities P4 of vaccine in preliminary experimental studies in monkeys This passage level has been chosen for its retention of cross protective character istics The vaccine strain H at passage 120 induces only a low level of interferon 5 but has lost its heterologous protection characteristics due to the attenuation of the virus b In order to produce a valuable immunological reaction in monkeys with the IB H52 vaccine it will be necessary to inoculate a high dose of live virus vaccine for example 10 8 median embryo infectious doses 100 000 000 EID 50 intranasally intramuscularly and or subcu taneously It is not expected that the virus will be infectious for macaques therefore a high dose will be required in order to achieve an adequate response of the immune system For more than 50 years avian IB infections have occurred worldwide and there are no reports of infection among human beings including in poultry farmers or other people who have had direct contact with highly contagious IB viruses of chickens c In the study using alpha IF in macaques the amount of SARS coronavirus virus SCV used for challenge was 1 10 6 median tissue culture infectious dose TCID 50 in 5 ml of PBS adminis tered intratracheally 4 However it was not mentioned in that publication whether or not a prechallenge titration of this virus was per formed It is very important to establish the amount of challenge virus which will provoke disease and eventually death Therefore before starting the experiment titration of the challenge virus in these monkeys should be performed in order to determine the amount of virus which will produce clinical symptoms in not more than 90 of the infected animals If an overdose is applied no real effect of the treatment will be demonstrable and if insuffi cient challenge virus is used no results will become available d It is of extreme importance that the H52 vaccine virus should be free of all micro organisms other than IB live vaccine virus therefore its production and passage in specific pathogen free SPF embryonated eggs is a prerequisite e It is proposed to challenge the vaccinated monkeys at 2 and 14 days after vaccination with a challenge SCV which has been titrated in macaques see point c This proposal is based on the likely immediate effect of the vaccine at 2 days through immunostimulation mechanisms and at 2 weeks if protection is observed through the heterologous cross protective activity of the vaccine virus It is without question that careful consideration by the relevant official health authorities must be given before an animal live virus vaccine is applied to human beings The application of the IB vaccine strain H in humans should be restricted and only HCWs and other persons at risk but not yet showing any signs of the disease will be considered as candidates for vaccination If clinical symptoms are observed other methods of treatment such as administration of alpha IF are recommended References 1 Bijlenga G Cook JKA Gelb J de Wit JJ Development and use of the H strain of avian infectious bronchitis virus from The Netherlands as a vaccine a review Avian Pathol 2004 33 550 7 2 Boots AMH Benaissa Trouw BJ Hesselink W Rijke E Schrier C 6 Marra MA Jones SJ Astell CR Holt RA Brooks Wilson A Butterfield YS et al The genome sequence of the SARS associated coronavirus Science 2003 300 1399 404 7 Seo HS Collisson EW Specific cytotoxic T lymphocytes are involved in in vitro clearance of infectious bronchitis virus J Virol 1997 71 5173 7 8 Seo HS Collison EW The carboxyl terminal 120 residue polypeptide of infectious bronchitis virus nucleocapsid induces cytotoxic T lymphocytes and protect chickens from acute infection J Virol 1997 71 7889 94 9 Seo HS Collisson EW Cytotoxic T lymphocytes responses to infectious bronchitis virus infection Adv Exp Med Biol 1998 440 455 60 10 Seo HS Pei J Briles WE Dzielwa J Collison EW Adoptive transfer of infectious bronchitis virus primed alphabeta T cells bearing CD8 antigen protects chicks from acute infection Virology 2000 269 183 9 11 Stavrinides J Guttman DS Mosaic evolution of the severe acute respiratory syndrome coronavirus J Virol 2004 78 76 82 12 Winterfield RW Fadly AM Potential for polyvalent infectious bronchitis vaccines Am J Vet Res 1975 36 524 6 13 Yu L Liu W Schnitzlein WM Tripathy DN Kwang J Study of protection by recombinant fowlpox expressing C terminal nucleocapsid protein of infectious bronchitis virus against challenge Avian Dis 2001 45 340 8 Letters to the Editor 265 Hensen EJ Induction of anti viral immune responses by immunization with recombinant DNA encoded avian corona virus nucleocapsid protein Vaccine 1992 10 119 24 3 Cavanagh D Review article Severe acute respiratory syndrome vaccine development experiences of vaccination against avian infectious bronchitis coronavirus Avian Pathol 2003 32 567 82 4 Haagmans BL Kuiken T Martina BE Fouchier KA Rimmelzwaan GF van Amerongen G et al Pegylated interferon alpha protects type 1 pneumocytes against SARS coronavirus infection in macaques published online 22 February 2004 Nat Med 2004 10 290 3 5 Holmes HC Darbyshire JH Induction of chicken interferon by avian infectious bronchitis virus Res Vet Sci 1978 25 178 81 G Bijlenga Chez Gavillet B P 9 74250 La Tour en Faucigny France Q 2005 The British Infection Society Published by Elsevier Ltd All rights reserved doi 10 1016 j jinf 2005 04 010