Virology 276, 202–213 (2000) doi:10.1006/viro.2000.0564, available online at http://www.idealibrary.com on Evaluation of Recombinant Vaccinia Virus—Measles Vaccines in Infant Rhesus Macaques with Preexisting Measles Antibody Yong-de Zhu,*,1 Paul Rota,† Linda Wyatt,‡ Azaibi Tamin,† Shmuel Rozenblatt,‡,2 Nicholas Lerche,* Bernard Moss,‡ William Bellini,† and Michael McChesney*,§,3 *The California Regional Primate Research Center and §Department of Pathology, School of Medicine, University of California, Davis, California 95616; †Measles Virus Section, Respiratory and Enteric Viruses Branch, Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333; and ‡Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892 Received June 20, 2000; returned to author for revision July 28, 2000; accepted August 1, 2000 Immunization of newborn infants with standard measles vaccines is not effective because of the presence of maternal antibody. In this study, newborn rhesus macaques were immunized with recombinant vaccinia viruses expressing measles virus hemagglutinin (H) and fusion (F) proteins, using the replication-competent WR strain of vaccinia virus or the replication- defective MVA strain. The infants were boosted at 2 months and then challenged intranasally with measles virus at 5 months of age. Some of the newborn monkeys received measles immune globulin (MIG) prior to the first immunization, and these infants were compared to additional infants that had maternal measles-neutralizing antibody. In the absence of measles antibody, vaccination with either vector induced neutralizing antibody, cytotoxic T cell (CTL) responses to measles virus and protection from systemic measles infection and skin rash. The infants vaccinated with the MVA vector developed lower measles-neutralizing antibody titers than those vaccinated with the WR vector, and they sustained a transient measles viremia upon challenge. Either maternal antibody or passively transferred MIG blocked the humoral response to vaccination with both WR and MVA, and the frequency of positive CTL responses was reduced. Despite this inhibition of vaccine-induced immunity, there was a reduction in peak viral loads and skin rash after measles virus challenge in many of the infants with preexisting measles antibody. Therefore, vaccination using recombinant vectors such as poxviruses may be able to prevent the severe disease that often accompanies measles in infants. © 2000 Academic Press INTRODUCTION and effective, they are neutralized in vivo by maternal antibody (Albrecht et al., 1977). To avoid the interference Measles virus (MV) is a negative-strand RNA virus in of maternal antibody, vaccine is administered at the age the Morbillivirus genus of the family Paramyxoviridae, of 9 months in developing countries and at 12–15 months and it is the causative agent of measles (Griffin and of age in the developed nations. The existence of a Bellini, 1996). Measles is a highly contagious childhood window of susceptibility to infection, between the time of disease characterized by fever and respiratory and sys- decay of maternal antibody below a protective level and temic infection. Measles in the infant is frequently asso- the time of vaccination, contributes to a worldwide child- ciated with serious complications and a high mortality hood measles mortality of 1,000,000 annually, mainly in rate. Measles cases have dropped dramatically world- the developing countries (World Health Organization, wide since the introduction of live, attenuated vaccines 1996). Recently, several reports demonstrated that in- in the 1960s, especially in the developed countries. fants even less than 4 months old can contract measles There were only 100 reported cases in the U.S. in 1999 (Oshitani et al., 1998; Wairagkar et al., 1998). The use of (CDC, 2000), and the interruption of indigenous MV trans- high-titered or inactivated measles vaccines was found mission in the U.S. has been maintained since late 1993 to be unacceptable as a means to overcome the inter- (CDC, 1996; Watson et al., 1998). Although the currently ference of maternal antibody (Aaby et al., 1988, 1993; used live, attenuated measles vaccines are very safe Fulginiti et al., 1967; Halsey, 1993; Kumar et al., 1998; Whittle et al., 1988). The two envelope glycoproteins of MV, the hemagglu- 1 Present address: Seattle Biomedical Research Institute, Seattle, tinin (H) and fusion (F) proteins, are important compo- WA. nents of a measles vaccine. During MV infection, the H 2 Present address: Tel Aviv University, Tel Aviv, Israel. and F proteins elicit both neutralizing antibodies and 3 To whom reprint requests should be addressed at California Re- gional Primate Research Center, University of California-Davis, Davis cellular immunity. Neutralizing antibodies prevent the CA 95616-8542. Fax: (530) 752-2880. E-mail: mbmcchesney@ucdavis. spread of extracellular virus and the cellular immune edu. response plays a critical role in the recovery from infec- 0042-6822/00 $35.00 Copyright © 2000 by Academic Press 202 All rights of reproduction in any form reserved. PREEXISTING ANTIBODY AND MEASLES VACCINATION 203 FIG. 1. Experimental design: vaccination of infant macaques with vaccinia recombinants expressing MV H and F proteins in the presence or absence of MIG or maternal antibody. tion (Burnet, 1968; Good and Zak, 1956). CTL epitopes RESULTS have been mapped to H and F in a human population (Jaye et al., 1998a,b). Thus, the expression of MV H and Experimental design and humoral immune responses F in a recombinant vector like vaccinia virus might be after vaccination able to circumvent the effect of maternal antibody and to As shown in Fig. 1, infant monkeys were divided into immunize the newborn host to H and F antigens. groups that received 0, 3.5, or 7 ml of MIG 48 h prior to Unlike rodents, Asian macaques contract measles vaccination. At 48 h, the geometric mean neutralizing naturally or experimentally, and the clinical signs of antibody titer (GMT) in the blood was 160 in Group 4, measles are similar to those in humans; thus, the which received 3.5 ml MIG (range 80–320), and the GMT monkey is a practical model for the study of measles was 452 in Group 5, which received 7 ml MIG (range pathogenesis and for the development of new measles 320–2560, Table 1). The GMTs achieved after adminis- vaccines (Griffin and Bellini, 1996; Hall et al., 1971; tration of MIG were similar to the GMT of 226 (range Kobune et al., 1996; McChesney et al., 1997; van Bin- 80–2560) measured in eight monkeys with maternally nendijk et al., 1994). Several studies have shown that derived antibody (Table 2). At the same 48 h time point recombinant vaccinia viruses expressing the MV H (day of vaccination), sera from six monkeys that received and F proteins can protect against MV infection in both 3.5 or 7 ml MIG were also measured by the conventional mice and monkeys (Drillien et al., 1988; van Binnendijk plaque reduction neutralization method, and a GMT of et al., 1997; Wild et al., 1992). The highly attenuated 2466 was calculated (range 1393–3734). These titers are modified vaccinia Ankara (MVA) has been used as a in the range for human newborns with maternal antibody recombinant expression vector and is being devel- (range 32–32,768; Sato et al., 1979). oped as candidate vaccine for humans (Moss et al., The infant monkeys were vaccinated by the intrader- 1996). The aim of the present study was to compare mal (id) route with either WR H&F or WR ␤ gal or by the the immunogenicity and protective efficacy of two vac- intranasal (i.n.) and intramuscular (im) routes with MVA cinia viruses, the WR strain and MVA, which express H&F or MVA control. Humoral immune responses to the measles H and F proteins, in infant monkeys in the vaccination were evaluated by virus neutralization and by presence of neutralizing antibody. MV neutralizing an- radio-immunoprecipitation (RIP) for antibodies to the H tibodies and CTL responses were measured after vac- and the nucleoprotein (N). Table 1 shows the titers of cination in the presence or absence of MV immune neutralizing antibody to MV after vaccination with WR ␤ globulin (MIG) or natural maternal antibody. Differing gal or WR H&F in the presence or absence of MIG. Very levels of protection were observed after a respiratory- low levels of MV neutralizing antibody (titers of 10–20) mucosal challenge with wild-type MV. were detected in the two infants of Group 1 vaccinated 204 ZHU ET AL. TABLE 1 Neutralizing Antibody Titers to Measles Virus in Monkeys Immunized with Recombinant Vaccinia (WR) in the Presence or Absence of MIG Reciprocal neutralizing antibody titer in immunized monkeys Group 2 Group 1 (WR ␤gal ϩ Group 3 Group 4 Group 5 (WR ␤gal) MIG 7 ml) (WR H&F ϩ PBS or NMS) (WR H&F ϩ 3.5 ml MIG) (WR H&F ϩ 7 ml MIG) wksa 30998b 31031 30999 31005 30305 30308 30989 31017 30310 30991 30990 31025 30997 31024 30327 30328 30330 30332 0 20 10 320 160 10 20 10 10 20 160 160 160 320 80 320 320 320 320 220Ͻ10 160 80 80 80 80 40 10 160 80 80 80 40 160 160 160 160 810Ͻ10 40 20 160 320 1280 160 40 20 20 160 40 20 80 10 20 10 10 Ͻ10 Ͻ10 20 10 160 640 1280 160 80 10 20 20 10 20 40 20 10 20 20 Ͻ10 Ͻ10 Ͻ10 Ͻ10 640 1280 1280 320 40 Ͻ10 10 20 10 20 10 20 20 40 22c 1280 640 1280 320 5120 1280 2560 1280 2560 640 320 1280 40 1280 640 1280 10 1280 a MIG, PBS, or NMS (normal monkey serum) was inoculated at 48 h prior to immunization at Week 0.