Airway allergy and viral infection.

There are complex interactions between airway allergy and viral infection. Available evidence suggests that viral respiratory infection can initiate, maintain and activate exacerbation of allergic conditions in respiratory tract. Innate and inflammatory responses to acute viral infection play important roles in its relationship to allergic reactions. On the other hand, biased immune responses toward Th2 caused by an allergic reaction may make the immune response ineffective in combating viral infection. It was previously shown that allergy can increase the expression level of rhinovirus receptors on mucosal epithelial cells. This suggests that airway allergy may increase the risk of rhinovirus infection. We have recently shown that allergy may also increase the expression level of influenza virus receptors. This suggests that airway allergy and viral infection may have a reciprocal interaction. The effect of allergy on the risk and outcome of viral infection needs to be further confirmed in clinical studies and its potential implication for clinical practice should be considered.

Trends of HIV seropositivity at Siriraj Hospital: 13 year's observation from 1992-2004.

OBJECTIVE: The aim of the present report was to observe the trend of seroprevalence rates of HIV seropositivity for routine services at Siriraj Hospital for 13 years. MATERIAL AND METHOD: The prevalence rate of HIV seropositivity was analyzed in three groups of subjects: 1) patients who attended the hospital with HIV related diseases; 2) pregnant women at first visit to the antenatal care clinic; 3) emigrating workers who have applied for employment in foreign countries. RESULTS: Of the 13 year-observation, HIV seroprevalence rates in the groups of patients, pregnant women and emigrating workers was 10.6% (95%CI 8.9-12.3%), 2.0% (95%CI 1.8-2.2%) and 0.6% (95%CI 0.4-0.8%), respectively. CONCLUSION: The low prevalence of HIV seropositivity in the group of emigrating workers may be due to self selection, whereas the prevalence in pregnant women, which was rather consistent at about 2.0%, may represent the infection rate in the general population. The seroprevalence rate measured in the group of pregnant women demonstrates that Thailand should increase efforts to confine the spread of HIV infection in the community.

Recombinant envelope protein of HIV-1 subtype E as antigen in HIV-1 antibody detection enzyme immunoassay.

In order to develop a reliable and inexpensive serodiagnostic method to be used for anti-HIV antibody detection in Thailand, recombinant envelope (TM or gp41 subunit) protein of HIV-1 subtype E was produced from prokaryotic cell (Escherichia coli) as the source of antigen in enzyme immunoassay (TE diagnostic EIA kit). HIV-1 gp41 subunit of subtype E was successfully expressed in E. coli in the form of polyhistidine-tagged proteins, comprising of rgp41A (601 bases N-terminal half of TM or 25kDa) and rgp41B (560 bases C-terminal half of TM or 24 kDa) by using an expression vector, pBAD/His C. The amount of protein, dilution of sera, and anti-human IgG labeled HRP used in the EIA test optimized by a checker board titration of the protein and seropositive or seronegative sera, were 5.0 microg/ml, 1:300, and 1:4,000, respectively. The blinded test evaluation of TE-diagnostic EIA in 500 seropositive and 500 seronegative sera which have been simultaneously tested by two available commercial kits and compared with our TE diagnostic EIA, gave 99.6% sensitivity and specificity. The other known genetic subtypes sera such as subtype A (n=5), B (n=9), C (n=4) and D (n=5) were also positive with this EIA. The estimated manufacturer cost per test of rgp41 based anti-HIV antibody detection EIA or TE-diagnostic EIA was about 15 baht. This recombinant envelope (gp41 or TM) protein from HIV-1, which can be produced in large quantities without any hazards from growing the virus and has lower cost to produce anti-HIV antibody serological diagnostic kit, should be considered as an HIV screening test in Thailand.

Detection of anti-human papillomavirus antibodies in patients with cervical neoplasia and in normal population.

Because of the relative simplicity of specimen collection comparing to HPV-DNA detection from cervical specimens, HPV serology might have a role in screening and prediction of cervical cancer risk. Serprevalences to HPV proteins in Thai population has not been assessed. The prevelences of antibodies to HPV-16 E6,E7 oncoproteins-derived peptides in peptides in patients with cervical intraepithelial neoplasia (CIN) and invasive cervical cancer, and in control group with normal cervical cytology were studied. The selected peptides were previously shown to contain immunodominant epitopes. The seroprevalences of antibodies to the peptides in the control group were 4.7% - 11.5%. The antibody to an E6 peptide (E6 aa 1-23) was found in 75.5% of patients with invasive cervical cancer, associated with cervical neoplasia. Eighty-five percent of patients with invasive cervical cancer and 17% of the control group had antibodies to at least one of the three peptides.

Antibody responses to two different yeast-derived hepatitis B vaccines.

Comparative study of antibody responses and adverse reactions after two different yeast derived hepatitis B vaccine administrations was performed. Subjects were 96 medical students who had seronegative for HBV markers. The first group of 47 students received H-B-Vax II® vaccine (MSD) 10 µg and the second group (49 students) received Engerix-B® vaccine (SKF-RIT) 20 µg. the vaccination schedule was two doses one month apart and a booster dose at sixth month. Antibody responses were measured at 1 month after each injection. The result showed that, seroconversion rate after booster dose was 100% in both groups. Anti-HBs titers after first and second doses showed no significant difference among two groups, but after booster dose the anti-HBs geometric mean titer was 3,070 mIU/ml in the first group and 6,634 mIU/ml in the second group, which showed statistical significance. Minor adverse reactions such as local pain, inflammation, itching, and malaise were found.