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Resume L’emergence de souches de cytomegalovirus (CMV) resistantes aux antiviraux et conduisant a l’echec therapeutique, constitue un probleme majeur survenant au cours de traitements prolonges chez les patients immunodeprimes. Trois inhibiteurs de l’ADN polymerase virale sont actuellement utilises pour traiter les infections a CMV, le ganciclovir (Cymevan®), le cidofovir (®), et le foscarnet (Foscavir®). Aucune de ces molecules n’est efficace sur le virus latent. Le ganciclovir (GCV) est la molecule la plus utilisee, en traitement curatif, en traitement anticipe et en prophylaxie. La resistance au ganciclovir est donc la plus frequente et la mieux etudiee. Les mutations de la phosphotransferase virale UL97, sont les premieres a apparaitre. Cette enzyme est responsable de la primophosphorylation du ganciclovir et de l’aciclovir dans les cellules infectees, indispensable a leur activation. Des mutations de l’ADN polymerase, codee par le gene UL54, surviennent plus tardivement et conduisent a une resistance croisee au cidofovir ou, plus rarement, au foscarnet. La recherche des souches resistantes par l’etude phenotypique est longue et difficile. Elle necessite l’isolement du virus en culture. L’approche moleculaire, basee sur la detection directe des mutations a partir du prelevement ou de l’isolat permet une mise en evidence precoce de la resistance. Des techniques rapides ont ete developpees. Cependant, ces techniques seduisantes sont actuellement limitees a la seule recherche des mutations les plus frequentes de UL97. L’etude de la sequence complete des genes UL97 et UL54, seule approche permettant de detecter toutes les mutations, reste peu pratiquee du fait de l’absence de standardisation des techniques. Elle est effectuee par des laboratoires specialises. La recherche et l’etude systematique des souches resistantes est toutefois necessaire au developpement de nouvelles molecules antivirales, et pourra guider, lorsqu’un eventail plus large sera disponible, un veritable choix therapeutique.

Summary Cytomegalovirus (CMV) can be transmitted by fresh blood components containing leukocytes. Consequences of CMV infection are serious in immunocompromised patients and in neonates. Thus, prevention of transfusion-transmitted CMV is of paramount importance. The use of blood products from CMV seronegative donors has been shown effective in preventing transmission. However, it does not completely eliminate the risk of transmission. Moreover, as CMV seroprevalence reaches 50 to 100% depending on the geographical and socioeconomic conditions, the availability of CMV seronegative products is limited. Leukodepletion of cellular blood products can be achieved by various filtration techniques. A method capable of achieving a residual leukocyte count 6 per unit allows for the reduction of CMV transmission to a level at least equivalent to the transfusion of seronegative blood components. Moreover, leukodepletion may reduce endogenous virus reactivation. Administration of filtered blood products from CMV seronegative donors is usually recommended for those patients at major risk of severe CMV transfusion-associated disease. The ability of the most efficient methods for blood filtration m preventing CMV transmission has to be assessed. Such methods would make it possible to avoid serological screening of blood donors.

Resume Le cytomegalovirus (CMV) est la premiere cause des infections virales congenitales dans le monde ; 0,4 a 2,3 % des nouveau-nes sont infectes, comme le montre la mise en evidence de la virurie ou d'une excretion pharyngee dans les deux premieres semaines de la vie. L'infection est asymptomatique a la naissance chez plus de 90 % de ces enfants, mais des atteintes neurosensorielles peuvent se manifester secondairement dans 5 a 17 % des cas. Quand l'infection est symptomatique a la naissance, elle peut etre lethale dans 30 % des cas et 90 % des survivants developpent d'importantes sequelles, en particulier neurologiques. L'infection a CMV acquise in utero est la cause principale des retards psychomoteurs d'origine infectieuse et des surdites congenitales. Le virus peut etre transmis au foetus quelque soit le type d'infection (primaire ou secondaire) maternelle ; cependant, l'infection symptomatique resulte, le plus souvent, d'une primo-infection. L'absence actuelle de traitement efficace de l'infection in utero ou a la naissance, rend indispensable la prevention de ces infections. La vaccination, si un vaccin sur et efficace est mis au point, serait une des armes de cette prevention, en prevenant la survenue de la primo-infection en cours de grossesse. Le respect de mesures d'hygiene, dans le but d'eviter la contamination par le virus, est egalement preconise chez la femme enceinte seronegative. Par contre, la recherche systematique en cours de grossesse, d'une eventuelle primo-infection chez la femme seronegative semble a deconseiller.

In a study concerning five CMV-infected bone-marrow-transplant recipients, five congenital CMV diseases and appropriate controls, presence of high levels of circulating interferon (IFN) was demonstrated exclusively during the course of CMV disease. This interferon was predominantly "immune" or gamma interferon (γ-IFN). These results suggest that during CMV disease the interferon compartment of the immune response is modified.

BACKGROUND: The hypothetical responsibility of sperm donation in cytomegalovirus (CMV) transmission to recipients and precautions to prevent this transmission are widely discussed. The aim of this French CECOS Federation study was to evaluate both the reality and the importance of the CMV risk due to donor sperm and the relevance of measures used to screen it. METHODS: We conducted a prospective multicentric study. CMV was detected by rapid and conventional cultures and by PCR in the frozen sperm of donors who met the normal criteria required of semen donors, irrespective of their CMV serological status. RESULTS: 635 samples from 231 donors (39.4% IgG + ) were obtained and tested by culture; 551 samples from 197 donors were also tested by PCR. From those samples, 0.78% were culture + , 1.57% culture + and/or PCR + ; 3.3% of seropositive donors and 0.72% of initially seronegative donors were culture + , but in the latter seroconversion occurred during the quarantine period; of the 197 PCR-tested donors, 3.5% (6.2/1.7) were PCR + , 3.3% (5.3/1.45) culture + and/or PCR + . PCR + samples can be culture- and vice versa. The most strongly positive sample corresponded to an initially seronegative donor. CONCLUSION: The best strategy to prevent potential CMV risk is to test donors for CMV IgG and IgM antibody at the outset and after a 6 month period of quarantine and to reject initially IgM seropositive donors or donors who seroconvert during the quarantine period.

Summary Rapid detection of human cytomegalovirus (HCMV) from blood was performed in parallel using inoculation into human fibroblastic cells of both 500 l of whole blood and of buffy coat derived from 9.5 ml of blood. Of the 46 samples tested, 20 were positive for HCMV, 18 when the buffy coat was inoculated (90 %) and 17 (85 %) when whole blood was used. Fifteen samples were positive by both techniques. Four samples gave discordant results: in three cases, viraemia was detected only by buffy coat assay and in one case only by whole blood assay. These results suggest that HCMV isolation from blood should be performed by inoculating whole blood into cell cultures if only small blood volumes can be collected.

Summary CMV can be detected in blood with two techniques: - isolation of CMV from the buffy-coat on human embryonic fibroblasts; - CMV genome detection by DNA hybridization technique. Isolation of CMV from blood plated on embryonic fibroblasts necessitates a delay of 10–30 days. Using monoclonal antibodies we have developped a 96 hours test to diagnose viremia. Fibroblasts grown on coverslip in tubes are inoculated with buffy-coat. Indirect immunoflourescence test is performed using the monoclonal antibodies E 13, 48 and 96 hours post-infection. DNA-DNA hybridrization technique necessitates purification of CMV DNA. CMV DNA is then labelled with 32 P by nick-translation. This labelled DNA is used as probe for detection of CMV genome in DNA extracted from leukocytes. The hydridization is virus-specific. Cytomegaloviremia correlates with active infection and is not indicate of the carrier state of blood donors. CMV genome research in blood can potentially identify infective donors. Further studies are needed to correlate CMV genome detection in blood with presence of CMV antibodies.