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http://ipsapp003.lwwonline.com/content/getfile/1980/106/3/abstract.htm
Parainfluenza type 3 virus (PIV-3) infections cause lower respiratory tract illness in children throughout the world. A licensed PIV-3 vaccine is not yet available.
A live attenuated cold-adapted (ca) and temperature-sensitive (ts) PIV-3 vaccine, designated cp-45, was evaluated sequentially in open label studies in 20 adults and in placebo-controlled, double blind studies in 24 PIV-3-seropositive children, 52 PIV-3-seronegative infants and children and 49 infants 1 to 2 months old. A single dose of this intranasal vaccine was evaluated in adults [106 plaque-forming units (pfu)] and seropositive children, and 104 and 105 pfu were evaluated in seronegative children. In the infant study, two 104 pfu doses of vaccine were administered at 1- or 3-month intervals. Safety, infectivity, immunogenicity and phenotypic stability of the vaccine were evaluated in all cohorts.
The cp-45 vaccine was well-tolerated in all age groups and infected 94% of vaccinated seronegative children and 94% of vaccinated infants. Although immunization with the first dose of cp-45 diminished the replication of a second dose in all infants, those immunized after 3 months shed vaccine virus more frequently than those immunized after 1 month (62% vs. 24%, respectively). Antibody responses to PIV-3 were readily detected in seronegative children with a variety of assays; however, the IgA response to the viral hemagglutinin-neuraminidase was the best measure of immunogenicity in young infants. Of 109 vaccine virus specimens recovered from nasal washes, 98 were ts and 11 were temperature-sensitive intermediate (tsi) viruses, with pinpoint plaques visible at 40°C. tsi viruses appeared transiently at the time of peak viral replication, represented a very small proportion of the total virus shed and were not associated with changes in clinical status. ca revertants were not detected.
The cp-45 vaccine is appropriately attenuated and immunogenic in infants as young as 1 month of age. Further development of this vaccine is warranted.
From the Center for Immunization Research, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD (RAK, BT, BB); the Department of Medicine, Saint Louis University, St. Louis, MO (RBB, FN, JC); Vanderbilt Vaccine Center, Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN (PFW, JT); Wyeth Research, Viral Vaccines, Pearl River, NY (TT, MP, SLW, YM, JH, JMT); and Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD (BRM).
Accepted for publication Jan. 9, 2003.
Address for reprints: Dr. Ruth A. Karron, Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Hampton House 117, 624 N. Broadway, Baltimore, MD 21205. Fax 410-955-2791; E-mail rkarron@jhsph.edu.
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