Yoshihiro Hirabayashi

Functional role of respiratory tract haemagglutinin-specific IgA antibodies in protection against influenza

Intranasal inoculation of haemagglutinin (HA) purified from influenza virus A/PR/8/34 (PR8, H1N1) together with cholera toxin B subunit, into Balb/c mice resulted in complete protection against PR8 infection in parallel with the induction of high levels of HA-specific IgA and IgG antibodies on the respiratory tract. The respiratory tract IgA and IgG were purified from nasal and lung washings of the immunized mice using affinity columns, and their HA-specific activities were measured by enzyme-linked immunosolvent, plaque neutralization and haemagglutination inhibition assays. The purified IgA and IgG had the following properties: (1) They were able to neutralize virus in vitro. (2) The purified IgA included major antibodies directed against PR8 virus and minor antibodies cross-reactive with A/Yamagata/120/86 (H1N1) or A/Fukuoka/C29/85 (H3N2) virus, while the purified IgG included major antibodies to the homotypic virus, minor antibodies to the H1N1 virus and only a trace amount of antibodies to the H3N2 virus. (3) When separated on a Sephacryl column, most of the IgA anti-HA activities occurred in the polymeric fractions of purified IgA, whereas the IgG anti-HA activities occurred in the monomeric fractions. (4) When passively administered to normal mouse respiratory tract before infection, the purified IgA protected against PR8 infection. These results suggest that HA-specific, polymeric IgA antibodies on the respiratory tract by themselves provide not only protection against the homotypic virus but also higher levels of heterotypic immunity than IgG.

Rapid and Simple Phenotypic Assay for Drug Susceptibility of Human Immunodeficiency Virus Type 1 Using CCR5-Expressing HeLa/CD4+ Cell Clone 1-10 (MAGIC-5)

ABSTRACT We describe a rapid and simple novel phenotypic assay for drug susceptibility of human immunodeficiency virus type-1 (HIV-1) using a CCR5-expressing HeLa/CD4+ cell clone 1-10 (MAGIC-5). MAGIC-5 cells produced large amounts of HIV-1 in culture supernatants, which enabled us to perform the phenotypic resistance assay. Determination of HIV-1 susceptibility to various protease inhibitors (PI) and nucleoside reverse transcriptase inhibitors was completed within 15 days in T-cell-tropic (X4) and macrophage-tropic (R5) viruses using fresh plasma samples containing at least 104copies/ml. The nucleotide sequence of the envelope V3 region of HIV-1 in plasma was almost identical to that of the virus isolated by MAGIC-5 cells, suggesting a lack of selection bias in our assay. The assay variability was confined to within five-fold in all drugs examined. Accordingly, we used a 10-fold increase in the 50% inhibitory concentration as the cutoff value for viral resistance in the present assay. HIV-1 resistant to lamivudine, which was not detected by conventional genotypic assays, was isolated. In HIV-1 with PI-associated primary amino acid substitutions, our assay showed that drug resistance profiles correlated well with previously reported genotypic-assay data. Furthermore, our assay provided comprehensive results regarding PI resistance in the presence of multiple mutations. The novel assay successfully quantified the level of resistance of clinical HIV-1 isolates to a battery of anti-HIV drugs, indicating its clinical usefulness, particularly in patients who failed to respond to antiretroviral chemotherapy.

Cross-protection against influenza B type virus infection by intranasal inoculation of the HA vaccines combined with cholera toxin B subunit

The relationship between the antibody responses to various influenza B type virus HA vaccines and protection against live B virus infection was investigated in Balb/c mice which had been inoculated intranasally with a combination of the HA vaccines and B subunit of cholera toxin (CTB) 4 weeks previously. The inoculation of HA vaccine, prepared from B/Ibaraki/2/85 (B/Ibaraki), B/Nagasaki/1/87 (B/Nagasaki) or B/Aichi/5/88 (B/Aichi) viruses, combined with CTB induced high levels of both nasal IgA and serum HI antibodies to any of B/Ibaraki, B/Nagasaki and B/Aichi viral antigens. Simultaneous inoculation of each CTB-combined HA vaccine provided complete protection against B/Ibaraki virus infection which is demonstrated by both rapid clearance of pulmonary virus and complete survival. On the other hand, the inoculation of HA vaccine prepared from B/Yamagata/16/88 (B/Yamagata) virus together with CTB induced only a low level of nasal IgA antibodies, cross-reactive to B/Ibaraki, B/Nagasaki and B/Aichi viral antigens and protected only partially against B/Ibaraki virus challenge. The involvement of the B type virus-specific immunity in this protection was suggested by the absence of protection against B/Ibaraki virus infection in mice previously inoculated with both A/PR/8/34 (H1N1) virus HA vaccine and CTB. These results suggest that antibodies to various influenza B viruses are cross-reactive to each B type virus antigens and that cross-protection against B virus infection could be conferred depending on the degree of B type virus cross-reactive immunity including secretory IgA antibodies.

A 5-day course of oral desensitization to trimethoprim/sulfamethoxazole (T/S) in patients with human immunodeficiency virus type-1 infection who were previously intolerant to T/S

BACKGROUND Trimethoprim/sulfamethoxazole (T/S) is an essential drug in patients with human immunodeficiency virus type-1 (HIV-1) infection to prevent opportunistic infections. About 40% to 60% of them develop skin rash which leads to discontinue the medication. A precise mechanism of the reaction is not known. OBJECTIVE To make the patients more tolerable to the medication and to make clear whether or not the reaction is caused by serum sulfamethoxazole-specific IgE. METHODS We established a 5-day protocol, in which T/S was administered orally as a granular form in increasing doses beginning with 0.005 g (it contains trimethoprim 0.4 mg and sulfamethoxazole 2 mg) and doubled every 12 hours until the therapeutic dose was achieved. We tried to desensitize T/S in 17 patients with HIV-1 infection who were previously intolerant to T/S and measured the specific IgE in sera. RESULTS Desensitization was successfully completed in 15 (88.2%) of the patients. In two patients who failed the desensitization, one was due to fever and the other was gastric irritation. During followup in a mean period of 16.6 months (range, 8 to 23 months) as of May, 1999, none has had Pneumocystis carinii pneumonia (PCP) while receiving T/S after desensitization. Sulfamethoxazole-specific IgE did not increase, indicating that it was not the major cause of skin rash due to T/S in our cases. CONCLUSION These preliminary results show that most patients who were thought to be intolerant to T/S and had no sulfamethoxazole-specific IgE can be safely desensitized and received the drug subsequently as an effective prophylaxis for PCP.

Sustained Cytomegalovirus-Specific CD4+ T Cell Response Associated with Prevention of Recurrence of Cytomegalovirus Retinitis without Secondary Prophylaxis after Highly Active Antiretroviral Therapy in Patients with AIDS

It has been demonstrated that the cytomegalovirus (CMV)-specific CD4(+) T cell response could be restored after ganciclovir and highly active antiretroviral therapy (HAART) in AIDS patients. In this study, we first confirmed the above observation cross-sectionally. We then performed a prospective longitudinal study over a period of 48 weeks. The second study included nine patients. All patients had received HAART. Five patients had a history of retinitis that was, however, under control after discontinuation of anti-CMV therapy more than 1 year before this study (group A). The other four had active CMV retinitis at the start of this study and anti-CMV therapy was required to control retinitis (group B). Median periods between commencement of HAART and the start of this study in group A and in group B were 27 and 4.5 months, respectively. Within both groups, the number of CD4(+) T cells that produced tumor necrosis factor alpha in response to CMV antigen did not vary throughout the observation period (Friedman test; p > 0.05). However, the median number of responsive CD4(+) T cells in group A patients was significantly higher than in group B (p < 0.05). Our results demonstrate that the number of CMV-responsive CD4(+) T cells increased when HIV was well controlled with HAART and was then maintained, and suggest that these cells may play an important role in the control of retinitis in patients with AIDS.

Equations for Estimating Area under Concentration Versus Time Curves for HIV Protease Inhibitors Used in HIV-Infected Patients and Evaluation of Their Effectiveness

Nobuhito Shibata*1, Asako Nishimura1, Kyoko Hukumoto1, Takashi Kuwahara2, Munehiro Yoshino3, Asako Uehira4, Takuma Shirasaka4, Yuka Hirajima5, Takehiro Imamura6, Atsushi Ajisawa6, Ryoto Tsuchiya7, Yoshihiro Hirabayashi7, Shinichi Oka7 and Kanji Takadal Department of Pharmacokinetics, Kyoto Pharmaceutical University1, Department of Pharmacy, Utano National Hospital2, Department of Pharmacy3 and Department of Infectious and Immunological Diseases4, Osaka National Hospital, Department of Pharmacy5 and Department of Infectious Diseases6, Tokyo Metropolitan Komagome Hospital, Clinical Research Laboratory, AIDS Clinical Center, International Medical Center7