IMMUNOGENICITY OF MEASLES VIRUS VACCINE STRAINS

USPHS的主要目标之一是在区域内消除 到2000年，麻疹，这一目标是可以实现的， 在免疫接种率和执行两剂计划方面， 麻疹疫苗 然而，仍有一些未解之谜 关于麻疹疫苗的最佳使用。 例如，研究是 为了了解最安全的免疫接种方法， 免疫缺陷儿童，如艾滋病毒感染者， 因感染麻疹而患上严重疾病或担任 麻疹病毒持续散发和传播的焦点， 阻碍根除工作。 该实验室参与了一项评估麻疹的临床试验 艾滋病毒阳性儿童的免疫接种。 ACTG 225是一个多中心， 单盲、随机临床试验，以评估安全性和 麻疹早期两剂疫苗接种后6个月和12个月免疫原性 与12个月时常规初次免疫相比， 年龄（CV）在HIV感染和未感染的婴儿。 110名婴儿 入组方案A（6个月和12个月时接种麻疹疫苗）或方案B （12个月时接种麻疹疫苗），并按艾滋病毒状况分层（艾滋病毒-组， A1[n=66]和B1[n=30]或HIV+组，A2[n=7]或B2[ n=7]）。 招生 1998年4月，由于HIV+的累积， 婴儿低符合增加使用抗逆转录病毒药物 在美国的孕妇治疗。 对麻疹疫苗的反应是 在研究第0、6、26和32周通过中和试验测量。 所有 艾滋病毒阳性儿童在6个月大时麻疹抗体滴度< 25，75%的儿童 婴儿也同样容易感染艾滋病毒。 阳转率 接受EV的HIV+儿童与接受CV的HIV+儿童进行了比较：3/4 (75 13个月大时检测时，HIV+EV儿童对MV有反应（%） 相比之下，4/4（100%）HIV+ CV。 有趣的是，5/5的HIV+EV对 第一剂MV，然而，一名儿童在接种前失去了麻疹抗体。 再次免疫，接种第二剂疫苗后无反应 在12个月大的时候 37/45（82%）的HIV-EV儿童对MV有反应 而13/13（100%）的HIV-CV应答。 虽然几何平均数 早期接种麻疹疫苗的儿童抗体滴度较低 比12个月大时接种疫苗的儿童的平均滴度高， 差异不显著。 未观察到严重不良反应 HIV+儿童EV或CV后，包括CD 4+淋巴细胞无减少 CD 4+淋巴细胞计数或百分比。 这些数据表明 HIV+婴儿的早期麻疹免疫可能有助于保护这一点， 弱势群体。 早期的疫苗接种计划可能会 在世界上麻疹和艾滋病毒流行的地区， 共循环

One of the major goals of the USPHS is the regional elimination of measles by the year 2000, a goal that is achievable due to an increase in immunization rates and implementation of a two dose schedule for measles vaccine. However, there are still some unanswered questions regarding optimal use of measles vaccines . For example, research is needed in order to understand the safest method for immunization of immunocompomised children, such as those with HIV infection, who could suffer serious disease as the result of measles infection or serve as a focus of persistent shedding and spread of measles virus that could impede eradication efforts. This laboratory participated in a clinical trial to evaluate measles immunization of HIV+ children. ACTG 225 was a multi-center , single-blinded, randomized clinical trial to assess the safety and immunogenicity of early two-dose measles vaccination at 6 and 12 months of age (EV) compared with conventional primary immunization at 12 months of age (CV) in HIV infected and uninfected infants. 110 infants were enrolled in regimen A (measles vaccine at 6 and 12 months) or regimen B (measles vaccine at 12 months) and stratified by HIV status (HIV- groups, A1[n=66) and B1[n=30] or HIV+ groups, A2[n=7] or B2[ n=7]). Enrollment into the study was discontinued in April, 1998 because accrual of HIV+ infants was low coincident with the increase use of anti-retroviral therapy in pregnant women in the US. Response to measles vaccine was measured by neutralization assay at study weeks 0, 6, 26 and 32. All HIV+ children had measles antibody titers < 25 by 6 months of age and 75% of HIV- infants were similarly susceptible. Seroconversion rates of HIV+ children who received EV were compared to HIV+ receiving CV: 3/4 (75%) HIV+EV children responded to MV when tested at 13 months of age compared to 4/4 (100%) HIV+CVs. Interestingly, 5/5 HIV+EV responded to the first dose of MV, however one child lost measles antibody prior to re-immunization and did not respond to the second dose when vaccinated at 12 months of age. 37/45 (82%) of HIV-EV children responded to MV while 13/13 (100%) of HIV-CVs responded. Although the geometric mean antibody titers of children receiving early measles vaccine was lower than the mean titer of children immunized at 12 months of age, these differences were not significant. No serious adverse affects were seen after EV or CV of HIV+ children including no decrease in CD4+ lymphocyte count or percentage of CD4 + lymphocytes. These data indicate that early measles immunization of HIV+ infants may help to protect this vulnerable population. An early vaccination schedule may have application in areas of the world where measles and HIV are cocirculating.