Search

We developed a carboxyfluorescein succinimidyl ester (CFSE)-based flow-cytometric assay that can detect different subsets of vaccinia-specific T cells capable of both antigen-specific expansion and protective effector functions. Proliferation and effector functions were detected by CFSE dilution and intracellular staining, respectively. Absolute numbers of CD4+/CFSElo/interferon (IFN)-γ+, CD8+/CFSElo/IFN-γ+,CD8+/CFSElo/granzyme A+, and CD8+/CFSElo /CD107a+ T cells present after in vitro stimulation with live vaccinia were significantly higher in immunized individuals (P< .05). These CD4+ and CD8+ T cell increases were >2 log higher than increases detectable by standard lymphoproliferation and cytotoxicity assays. Vaccinia-specific CD8+/CFSEloIFN-γ+ and granzyme A+ T cell responses were significantly correlated with the results of standard 51Cr-release cytolytic assays (P< .05). Furthermore, vaccinia induced antigen-specific memory γδ T cells. We demonstrate that vaccinia induces robust memory effector CD4+, CD8+, and γδ T cells, all of which are relevant for protection against smallpox. CFSE-based flow-cytometric assays will be useful in evaluating cell-mediated immune responses induced by new smallpox vaccines. [ABSTRACT FROM AUTHOR]

Induction of local antibody responses to influenza A virus hemagglutinin by coadministration of two vaccines was investigated. Fifty elderly nursing home residents received inactivated trivalent influenza virus vaccine intramuscularly and simultaneously were randomized to receive either bivalent live attenuated influenza A virus vaccine or saline placebo intranasally in a blinded fashion. More significant increases in anti-H1 and -H3 IgA antibodies were detectable in nasal wash specimens of subjects who received live attenuated virus vaccine than in those who received intranasal placebo. The increased anti-hemagglutinin IgA antibody response was of longer duration in recipients of live attenuated vaccine. The change in antibody titers after vaccination was positively correlated with total blood lymphocyte counts measured before vaccination in both vaccinee groups (P < .05). There was a possible advantage of administering live attenuated with inactivated virus vaccines because of enhanced local antibody responses. [ABSTRACT FROM PUBLISHER]

The safety, infectivity, immunogenicity, and phenotypic stability of the cold-passaged (cp) candidate vaccine cp-45, a cold-adapted (ca), temperature-sensitive (ts) mutant of the J8 strain of human parainfluenza virus type 3 (HPIV-3), was evaluated in 114 children 6 months to 10 years old in a randomized, placebo-controlled, double-blind trial. The cp-45 vaccine was well tolerated when given intranasally to parainfluenza virus type 3 (PIV-3)-seropositive and -seronegative children. With 104 or 105 TCID50 of cp-45 vaccine, 86% of seronegative vaccinees were infected, 83% of whom shed virus at a mean peak titer of 102.2 pfu/mL. Virus present in respiratory specimens retained the ts phenotype, and each of 86 PIV-3 isolates tested retained both the ca and ts phenotypes. One dose of 105 TCID50 of vaccine induced a serum hemagglutination-inhibiting antibody response in 81% of vaccinees; the geometric mean titer was 1:32. These studies indicate that the cp-45 HPIV-3 vaccine is satisfactorily attenuated, infectious, immunogenic, and phenotypically stable and merits further evaluation in infants and young children. [ABSTRACT FROM PUBLISHER]

Twenty-two healthy infants and children received either cold-recombinant, trivalent influenza vaccine or placebo in a three-dose vaccine trial. Most (82%) who received vaccine were seronegative to all three vaccine strains (106 TCID50/dose each): A/Kawasaki/9/86 (H1N1), A/Los Angeles/2/87 (H3N2), and B/Yamagata/16/88. Vaccine was administered intranasally at time 0 and 2 and 4 months later. The vaccine was well tolerated and immunogenic when administered in a multidose regimen. The first dose stimulated antibody to H1, H3, and Bin 59%, 94%, and 35% of vaccinees, respectively, by hemagglutination inhibition (HAI) or ELISA. After two doses of vaccine, 93%, 93%, and 80% had antibody by HAI or ELISA to H1, H3, and B, respectively. Most vaccinees (67%) responded to all three viruses after two doses of vaccine. The third dose contributed little to the vaccine's immunogenicity. Multidose trivalent influenza vaccine is safe and induces an immune response in most vaccinees after two doses. [ABSTRACT FROM PUBLISHER]

Seventeen triply seronegative infants and young children, and 15 infants and young children seropositive to all three influenza virus strains were vaccinated intranasally with 105 TCID50 of each of three (H1N1, H3N2, and B) live attenuated, cold-adapted influenza vaccine strains. Seventeen controls were given placebo. Vaccination with trivalent influenza vaccine was not associated with adverse reactions in triply seronegative or seropositive children. Overall, 12 (71%), 13 (76%), and 13 (76%) of seronegative children were infected by H1N1, H3N2, or B vaccine viruses, respectively, as indicated by viral shedding or by hemagglutination inhibition assay or ELISA antibody response. Of the triply seronegative children, 47% shed all three viruses; 7 children had an antibody rise to all three vaccine viruses and 4 shed all three viruses. A dose of 104.4–105.0 TCIDso of each of three intranasally administered vaccine viruses was safe, immunogenic and antigenic; however, strategies to increase the proportion of children infected by each of the vaccine viruses should be studied, including higher doses and multiple doses oflive trivalent vaccine. [ABSTRACT FROM PUBLISHER]

A letter to the editor is presented in response to the article titled "Interferon-Mediated Antiviral Immunity Against Orthopoxvirus Infection Is Provided by T cells," by C. Agrati, C. Castiletti and R. De Santis, published in a 2006 issue of the "Journal of Infectious Diseases."

We developed a carboxyfluorescein succinimidyl ester (CFSE)-based flow-cytometric assay that can detect different subsets of vaccinia-specific T cells capable of both antigen-specific expansion and protective effector functions. Proliferation and effector functions were detected by CFSE dilution and intracellular staining, respectively. Absolute numbers of CD4(+)/CFSE(lo)/interferon (IFN)- gamma (+), CD8(+)/CFSE(lo)/IFN- gamma (+), CD8(+)/CFSE(lo)/granzyme A(+), and CD8(+)/CFSE(lo)/CD107a(+) T cells present after in vitro stimulation with live vaccinia were significantly higher in immunized individuals (P<.05). These CD4(+) and CD8(+) T cell increases were >2 log higher than increases detectable by standard lymphoproliferation and cytotoxicity assays. Vaccinia-specific CD8(+)/CFSE(lo)/IFN- gamma (+) and granzyme A(+) T cell responses were significantly correlated with the results of standard (51)Cr-release cytolytic assays (P<.05). Furthermore, vaccinia induced antigen-specific memory gamma delta T cells. We demonstrate that vaccinia induces robust memory effector CD4(+), CD8(+), and gamma delta T cells, all of which are relevant for protection against smallpox. CFSE-based flow-cytometric assays will be useful in evaluating cell-mediated immune responses induced by new smallpox vaccines.