Immunogenicity and safety in adults of a new chromatographically purified Vero-cell rabies vaccine (CPRV): a randomized, double-blind trial with purified Vero-cell rabies vaccine (PVRV)

Recent improvements in chromatographic purification procedures have made it possible to develop a new chromatographically purified rabies vaccine (CPRV) by further purifying the current rabies vaccine prepared from Vero-cell culture (Verorab; Pasteur Mérieux Connaught). The immunogenicity and safety of primary immunization, followed by a booster at one year, with CPRV was compared to that of the purified Vero cell vaccine (PVRV) in a randomized, double-blind study carried out at four veterinary schools in France. A total of 330 healthy, male and female, first-year veterinary students, aged at least 18 years and who required pre-exposure rabies prophylaxis, were enrolled in this study. Included subjects were randomly assigned either CPRV (n = 163) or PVRV (n = 167) to be given as a primary immunization series of three intramuscular injections (D0, D7, D28), followed by a booster after 1 year (D365). Blood samples for serological analysis were taken at D0 (before first injection), D28, D42, D180, D365 (before booster) and D379. All subjects developed a strong immune response to the primary series, and at D42, all subjects had seroconverted for rabies neutralizing antibody (serum titre > or = 0.5 IU/ml). The rabies virus-neutralizing antibody GMT value at D42 in the CPRV group (23.0 IU/ml) was non-inferior to that in the PVRV group (29.6 IU/ml), according to a one-sided non-inferiority test. While antibody titres tended to decrease over the period of follow-up, at D365 (before booster), 97.5% subjects in the CPRV group and 98.8% of subjects in the PVRV group remained seroconverted. After booster, although the rabies antibody GMT value in the CPRV group was lower than that in the PVRV group, all subjects in both groups were seroconverted, and the difference is probably not clinically important. The incidence of local and systemic reactions tended to decrease with each dose during the primary immunization series, followed by a slight increase after booster (significant time-effect in an exploratory logistic regression analysis). Although mild or moderate local reactions tended to be more frequent after injection with CPRV compared to PVRV, systemic reactions were reported less often (significant group-effects in exploratory logistic regression analyses). One serious adverse event possibly related to vaccine occurred during this study (severe asthenia after the third dose of PVRV). This comparative study in healthy young adults demonstrates that the new chromatographically purified rabies vaccine is as immunogenic as PVRV, and seems to be associated with fewer systemic reactions.

[Vaccinations of the traveller]

Travelers' immunization has 2 aims: for the traveler, to prevent the risk of contracting an endemic disease during his stay abroad; for the community to prevent the risk of importing an infectious agent yet unknown in the country. Travelling offers an opportunity to update routine immunizations: tetanus, diphtheria, poliomyelitis, hepatitis B; for young people: measles and rubella; for elderly people: influenza. Two vaccinations are compulsory: yellow fever for travelers to tropical Africa and Amazonian forest; meningococcus A + C for Mecca pilgrims. Other vaccines are recommended for travelers to specific areas: typhoid fever, hepatitis A, cholera in countries with poor hygiene; rabies for exposed travelers (expatriates, trekkers...); Japanese encephalitis for persons spending a month or longer in rural agricultural areas during the monsoon season; tickborne encephalitis for persons visiting forested areas of central Europe from may to september. Yet, most of travelers' diseases such as malaria cannot be prevented by vaccination and appropriate preventive measures (chemoprophylaxis and protection against insects) should be taken.

RU 41 740 (Biostim) and IL-4, or IL-13, have opposite effects on CD14, CD23, HLA-DR and HLA-DQ on monocytes

RU 41 740 (Biostim) is a glycoprotein extract obtained from Klebsiella pneumoniae. Its immunostimulating properties on monocytes have been established in vivo and in vitro. To confirm its spectrum of action at molecular level we studied its role on the modulation of four molecules involved in antigen presentation (HLA-DR, HLA-DQ), uptake of endotoxin (CD14) and activation (CD23). These four molecules are known to be modulated by interleukins IL-4 and IL-13. We found that HLA-DR, HLA-DQ, CD14 and CD23 were differentially regulated by biostim and IL-4 or IL-13. Surprisingly, Biostim inhibited the IL-4 or IL-13-induced expression of CD23, HLA-DQ and HLA-DR, while it did not have any action on these molecules by itself. We therefore hypothesize that Biostim, through the action on its receptor, could interact with the IL-4 receptor and IL-13 receptor and/or inhibit the IL-4 and IL-13 receptor transducing signal.

A 3-week hepatitis B vaccination schedule provides rapid and persistent protective immunity: a multicenter, randomized trial comparing accelerated and classic vaccination schedules

Hepatitis B (HB) vaccinations given once weekly for 3 weeks can provide early seroprotection. This study compared immune responses induced by the accelerated (A; days 0, 10, 21) and classic (C; days 0, 28, 56) HB vaccination schedules. Two hundred seventy healthy subjects (95 men, 175 women) with a mean age of 23.8 years received 3 doses of GenHevac B, a recombinant vaccine produced in mammalian cells. The subjects were randomly assigned to schedules A or C. A booster dose was given 1 year later. One month after the third dose, 70% (schedule A) and 92% (schedule C) of the subjects were seroprotected and 100% (A) and 99% (C) had developed anti-pre-S2 antibodies. Before booster injections, 93% (A) and 95% (C) of the subjects were seroprotected, and 1 month after the booster, almost all subjects were seroprotected. A 3-week HB vaccination schedule with GenHevac B can confer early protective immunity lasting up to 1 year.

Three-week hepatitis B vaccination provides protective immunity

To determine whether a 3-week hepatitis B (HB) vaccination could achieve protective immunity, 89 healthy non-immunized young adults received three doses of 20 micrograms each of HBs antigen (GenHevac B, Pasteur) and were randomly assigned to schedule A (n = 44): two doses at day 0, one dose at day 21; or schedule B (n = 45): one dose at days 0, 10 and 21. Seroprotection rates (anti-HBs > or = 10 mIU ml-1) for groups A and B respectively were: 23 and 40% at day 21; and 77 and 91% at day 82 (not significant). Anti-HBs geometric mean titres were higher in group B than in group A (p < 0.05) at days 21 (6.4 versus 3.8) and 82 (77.6 versus 33.5). One year after primary vaccination, the seroprotection rate remained as high as 90% in the vaccinees of group B; after boosting all vaccinees had protective levels of anti-HBs antibodies. Thus 3-week HB vaccination with GenHevac B allowed early and durable protective immunity.