Variable sequences in the long terminal repeat and Its downstream region of some of HIV Type 1 CRF01_AE recently distributing among Thai carriers.

Human immunodeficiency virus type 1 (HIV-1) proviral DNA sequences in and downstream of the 5' long terminal repeat (LTR) were compared among samples obtained from 13 HIV-1 CRF01_AE-infected individuals in Thailand from 1998 to 1999. Eleven individuals had highly conserved sequences compared with previously reported CRF01_AE viruses. However, T cell-specific factor (TCF)-1alpha motif, which is located just beside the 3' terminus of the nef sequence, was duplicated in 2 out of the 13 subjects, one of whom had also lost the 24 nucleotides next to the 3' of the primer-binding site. Thus, several characteristics of CRF01_AE LTR and gag-leader sequence were identified in some samples recently obtained in Thailand.

Full-length sequences of two CRF01_ae (subtype e) HIV type 1 isolates from 1995 samples of patients with sexually transmitted diseases in Thailand.

We isolated two CRF01_AE human immunodeficiency virus type 1 (95TNIH022 and 95TNIH047) from the 1995 blood samples derived from asymptomatic carriers in Ubonratchatani province of northeastern Thailand. Both isolates can replicate in peripheral blood mononuclear cells, but not in several T cell lines examined. The full-length sequences recovered from proviruses in infected cells by long-range polymerase chain reaction were determined. Phylogenetic analyses of these sequences at individual genes showed them to be closely related to those of reported CRF01_AE HIV-1, such as 1990 isolate CM240 and 1993 isolate 93TH253. Two isolates in this study also showed a similar pattern of CRF01_AE mosaicism and a similar structure at the long terminal repeat, i.e., a copy number of NF-kappaB binding sites, sequence at the TATA box, and the putative secondary structure of stem-loop in the transactivation response region. Our results showed that 1995 Thai E isolates could contribute to our understanding of the epidemiology, pathogenesis, and diagnostics of HIV-1 CRF01_AE and further to vaccine development.

Low or no antibody responses to human immunodeficiency virus type 1 Nef in infected carriers with subtype E, in contrast to subtype B that showed antibodies preferentially recognizing subtype-specific Nef epitopes.

The viral accessory gene product Nef has been shown to play an important role in human immunodeficiency virus type 1 (HIV-1)-induced pathogenesis. Only little information is available regarding the differences in the host immune responses against Nef protein and its function in vivo among different subtypes of HIV-1. In the present study, we showed marked differences in the immune responses to Nef protein between subtypes B and E. The amino acid sequence in subtype E Nef showed 72% homology with that in subtype B. Most murine monoclonal antibodies obtained by immunization with subtype B or E Nef protein showed cross-reactivity with both Nef proteins (80 and 67%, respectively). Next, we focused on the immune responses among infected Japanese and Thai individuals. Subtyping of the individuals into B and E was carried out by enzyme-linked immunosorbent assay (ELISA) using synthetic peptides corresponding to the V3 loop representing the principal neutralizing domain. Most of the sera from these individuals reacted strongly with Gag p24 proteins derived from subtypes B and E at similar levels. However, the immune responses among these individuals to Nef protein were markedly different. Some subtype B-infected Japanese and Thai individuals (40 and 35%, respectively) showed higher levels of anti-Nef antibodies, although these antibodies preferentially recognized epitopes specific to subtype B. On the other hand, most of the subtype E-infected Japanese and Thai individuals showed low or no antibody responses to Nef proteins. Thus, immune responses to Nef were markedly different between subtypes B- and E-infected carriers, suggesting different function(s) for Nef in AIDS pathogenesis. Further, vaccine design must take into account the different subtypes of HIV-1.

Highly variable sequences in the env V3 region of HIV type 1 distributing among Thai carriers from 1995 to 1997.

The amino acid sequences of the Env V3 region of HIV-1 subtype E in Thailand were highly variable in the samples obtained from 1995 to 1997, compared with the previously reported sequences in samples obtained from 1990 to 1993. The sequences of the V3 region in the samples from five provinces in Thailand revealed that the variability was much higher in the samples from Bangkok and Ubonrachathani than in those from Chiangmai, Prathumthani, and Trang. There was no apparently different level of diversity at the V3 region in the samples from symptomatic and asymptomatic individuals. The V3 loop motif in most (66.7%) of the samples was GPGQ, although this motif was more heterogeneous in the samples from Bangkok and Ubonrachathani than in those from the other three provinces. The N-linked glycosylation sites in the V3 region among these samples were relatively conserved. There was no apparent difference in the presence of positively charged amino acids at positions 306 and 320 between the samples from symptomatic and asymptomatic individuals.

The association of skin diseases with human herpesvirus 8 infection in HIV carriers.

The seroprevalence to Kaposi's sarcoma-associated herpesvirus (KSHV) or human herpesvirus type 8 (HHV-8) was surveyed in human immunodeficiency virus type 1 (HIV-1) carriers with or without skin diseases, and also in HIV-1 negative individuals in Thailand. Using an immunofluorescence assay, the seropositive rates to lytic antigens of HHV-8 in HIV-1 carriers with or without skin diseases were 25% and 7.4%, respectively, but none of HIV-1 negative individuals had antibody. The seroprevalence to HHV-8 antigens was high in HIV positive individuals with low CD4/CD8 ratio, suggesting that HHV-8 is reactivated during the immunosuppressive state. Several polypeptides with apparent molecular weights of 34-38,000 and 40,000, which were specific to HHV-8, were identified by the immunoprecipitation test using the seropositive sera. Our results suggested that HHV-8 co-existed with HIV in HIV-1 carriers and the existence of HHV-8 may be associated with clinical features in the skin.

Unusually high seroprevalence of Borna disease virus in clade E human immunodeficiency virus type 1-infected patients with sexually transmitted diseases in Thailand.

The seroprevalence of Borna disease virus (BDV) in human immunodeficiency virus type 1-infected individuals in Thailand was examined by using recombinant BDV p24. A high (38 to 48%) rate of seroprevalence of BDV was observed in clade E-infected patients with sexually transmitted diseases, compared with those in clade E-infected prostitutes (8.3%), pregnant women (0%), clade B-infected intravenous-drug users (0%), and human immunodeficiency virus type 1-negative blood donors (1.9%).

PIP: Borna disease virus (BDV) is a neurotropic, yet unclassified, nonsegmented, negative-sense, single-stranded RNA virus which naturally infects horses and sheep, and induces a disease characterized by a progressive meningoencephalopathy. It has been suggested that BDV, or a related agent, is associated with specific psychiatric disorders. Previous seroprevalence studies of HIV-1-infected individuals identified a BDV seroprevalence of 4-8% at the early stage of HIV-1 infection which grew to 13.9% in later stages. BDV may be more widespread than previously thought and possible reactivated in immunosuppressed patients. BDV seroprevalence in HIV-1-infected individuals in Thailand was examined using recombinant BDV p24. The rates of infection were 38-48% in clade E-infected patients with sexually transmitted diseases, 8.3% in clade E-infected prostitutes, 0% in pregnant women, 0% in clade B-infected IV drug users, and 1.9% in HIV-1-negative blood donors.

Effects of human alpha, beta and gamma interferons on varicella zoster virus in vitro.

The antiviral effects of interferon (IFN) on varicella zoster virus (VZV) and herpes simplex virus (HSV) in vitro were examined. The values for the 50% inhibitory dose (ID50) of IFN-alpha, beta and gamma determined by plaque reduction assay, were 0.813, 0.650 and 13.750 IU/ml, respectively, against VZV and 18.00, 10.38 and 115.0 IU/ml, respectively, against HSV. Thus IFN-alpha and beta were more effective than IFN-gamma against both VZV and HSV and VZV was more sensitive than HSV to the IFNs. Five mutants of VZV which were resistant to acyclovir (ACV), phosphonoacetic acid (PAA) or bromodeoxyuridine (BUDR) were also sensitive to IFN beta, their average ID50 being 1.31 IU/ml. Analysis of virus-specific proteins by the immunofluorescent technique with various antisera showed that IFN had a significant effect before early protein synthesis.

Hantaanvirus among urban rats from a slum area in Bangkok.

A total of 106 rodents sera from slum Wat Phai Ton and slum Klong Toey were examined by immunofluorescent antibody assay during May to August 1990. The positive sera were further tested by plaque reduction neutralization test with the prototype hantaanvirus and the rat-associated hantaan like virus. Isolation attempts were also performed from their tissues. Antibody-positive rats were found in both slum areas, 32.7% in slum Wat Phai Ton and 5.6% in slum Klong Toey. Rattus norvegicus was the major species found positive. Positive plaque reduction neutralization results indicated that the infecting virus was antigenically similar to the strain of rat-associated hantaanvirus. The presence of low titer antibodies (IFA titer 32 to 128) may be an obstacle to isolation of associated virus using tissue culture.

Immunofluorescence, enzyme-linked immunosorbent assay, particle agglutination and western blot for the detection of antibody to human immunodeficiency virus type 1.

Immunofluorescence assay (IFA) has been applied for detection of antibody to human immunodeficiency virus type 1 (HIV-1). To compare the IFA with an enzyme-linked immunosorbent assay (ELISA) and particle agglutination (PA), we examined the antibody response to HIV-1 in 475 sera from AIDS, PGL and ARC patients as well as several risk groups and healthy persons by three methods. The positive results by any methods were confirmed by western blot (WB). The results by all methods were well correlated on the sera from 45 asymptomatic male homosexuals and 70 female prostitutes. There were some false positive results by ELISA in the sera from prisoners and healthy persons. Four sera from drug abusers were positive only by PA and IFA and were negative by ELISA. All were WB-inconclusive. Particle agglutination and IFA results were compared with western blot analysis on 208 ELISA-positive sera. All IFA-strongly positive sera (84%) were positive by western blot. The sera with weakly positive, negative and inconclusive results by IFA (16%) were possibly any of positive, inconclusive or negative by western blot. By PA, 200 of 208 (97%) sera were PA-positive and 1% of these sera were WB-inconclusive while the PA-negative sera were either negative or inconclusive by western blot. These results suggested that PA is a simple and sensitive method for screening of HIV-1 antibody while IFA could be a primary confirmatory test and western blot would then be used for confirming any IFA-negative or inconclusive results.

Prevalence of antibody to human herpesvirus 6 in women and children.

The antibody prevalence to human herpesvirus 6 (HHV-6) was compared between pregnant women and control women of similar ages in Thailand. No significant difference was detected in the antibody positive rate and antibody titers between both groups. The antibody titers in sera collected from pregnant women at 1st and 3rd trimester remained unchanged. Next, the antibody prevalence in infants were examined and the positive rate decreased until 3 months and started to increase from 6 months after birth. The present results suggest that the reactivation of HHV-6 might not occur during pregnancy and this virus infects infants postnatally.