RESUMO
HIV-1 transmission worldwide is predominantly associated with heterosexual activity, and non-clade B viruses account for the most spread. The HIV-1 epidemic in Trinidad/Tobago and the Caribbean shares many features with such heterosexual epidemics, including a prominent role for coincident sexually transmitted diseases. This study evaluates the molecular epidemiology of HIV-1 in Trinidad/Tobago during a period when abrupt transition from homosexual to heterosexual transmission occurred in the absence of injecting drug use, concomitant with a rapid rise in HIV-1 prevalence in the heterosexual population. Of 31 viral isolates studied during 1987-1995, all cluster with subtype B reference strains. In the analysis of full env genes from 22 early seroconverters, the Trinidad isolates constitute a significant subcluster within the B subtype. The Trinidad V3 consensus sequence differs by a single amino acid from the prototype B V3 consensus and demonstrates stability over the decade of this study. In the majority of isolates, the V3 loop of env contains a signature threonine deletion that marks the lineage of the Trinidad HIV-1 clade B epidemic from pre-1984. No phenotypic features, including syncitium induction, neutralization profiles, and chemokine receptor usage, distinguish this virus population from other subtype B viruses. Thus, although the subtype B HIV-1 viruses being transmitted in Trinidad are genetically distinguishable from other subtype B viruses, this is probably the result of a strong founder effect in a geographically circumscribed population rather than genetic selection for heterosexual transmission. These results demonstrate that canonical clade B HIV-1 can generate a typical heterosexual epidemic.
Assuntos
Infecções por HIV/transmissão , HIV-1/classificação , Comportamento Sexual , Sequência de Aminoácidos , Sequência de Bases , Primers do DNA , Feminino , Proteína gp120 do Envelope de HIV/química , Proteína gp120 do Envelope de HIV/genética , Infecções por HIV/epidemiologia , Humanos , Masculino , Dados de Sequência Molecular , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/genética , Homologia de Sequência de Aminoácidos , Especificidade da Espécie , Trinidad e Tobago/epidemiologiaRESUMO
While the worldwide AIDS epidemic continues to expand, directly measured incidence data are difficult to obtain. Methods to reliably estimate human immunodeficiency virus type 1 (HIV-1) incidence from more easily available data are particularly relevant in those parts of the world where prevalence is rising in heterosexually exposed populations. The authors set out to estimate HIV-1 incidence in a population of heterosexual sexually transmitted disease clinic attendees in Trinidad who had a known high prevalence of HIV-1 subtype B. Over the period 1987-1995, HIV-1 incidence estimates from serial cross-sectional studies of HIV-1 prevalence, passive follow-up of clinic recidivists, modeling of early markers of HIV-1 infection (p24 antigen screening), and a cohort study of seronegative genital ulcer disease cases were compared. Measuring incidence density in the genital ulcer disease cases directly gave the highest estimate, 6.9% per annum. Screening for the detection of early HIV-1 markers yielded an incidence of 5.0% per annum, while estimating incidence from serial cross-sectional prevalence data and clinic recidivists gave estimates of 3.5% and 4.5% per annum, respectively. These results were found to be internally consistent. Indirect estimates of incidence based on prevalence data can give accurate surrogates of true incidence. Within limitations, even crude measures of incidence are robust enough for health planning and evaluation purposes. For planning vaccine efficacy trials, consistent conservative estimates may be used to evaluate populations before targeting them for cohort studies.
PIP: HIV incidence data, necessary for the planning and evaluation of national AIDS control programs, are difficult to obtain directly. In this study, HIV-1 incidence in Trinidad was estimated in a population known to be at high risk: heterosexuals attending a sexually transmitted disease clinic in Port of Spain in 1987-95. HIV incidence estimates were obtained from serial cross-sectional studies of HIV-1 prevalence (n = 3625), passive follow-up of clinic recidivists (n = 98), modeling of early markers of HIV-1 infection (p24 antigen screening) (n = 12,154), and a cohort study of seronegative genital ulcer disease cases (n = 196). Measuring incidence density in genital ulcer disease cases directly gave the highest estimate: 6.9% per year. Screening for the detection of early HIV-1 markers yielded an incidence of 5.0% per year, while estimating incidence from serial cross-sectional prevalence data and clinic recidivists provided estimates of 3.5% and 4.5%, respectively. Although these estimates come from groups within the clinic population with differential HIV-1 risk, they were internally consistent. These findings suggest that indirect estimates of incidence based on prevalence data can provide accurate surrogates of true HIV incidence and may be used to target suitable populations for cohort studies.
Assuntos
Infecções por HIV/epidemiologia , HIV-1 , Western Blotting , Estudos Transversais , Ensaio de Imunoadsorção Enzimática , Feminino , Seguimentos , Anticorpos Anti-HIV/análise , Proteína do Núcleo p24 do HIV/imunologia , Infecções por HIV/imunologia , HIV-1/imunologia , Humanos , Incidência , Masculino , Prevalência , Reprodutibilidade dos Testes , Estudos Retrospectivos , Trinidad e Tobago/epidemiologiaRESUMO
While the worldwide AIDS epidemic continues to expand, directly measured incidence data are difficult to obtain. Methods to reliably estimate human immunodeficiency virus type 1 (HIV-1) incidence from more easily available data are particularly relevant in those parts of the world where prevalence is rising in heterosexually exposed populations. The authors set out to estimate HIV-1 incidence in a population of heterosexual sexually transmitted disease clinic attended in Trinidad who had a known high prevalence of HIV-1 subtype B. Over the period 1987-1995, HIV-1 incidence estimates from serial cross-sectional studies of HIV-1 prevalence, passive follow-up of clinic recidivists, modeling of early markers of HIV-1 infection (p24 antigen screening), and a cohort study of seronegative genital ulcer disease cases were compared. Measuring incidence density in the genital ulcer disease cases directly gave the highest estimate, 6.9 percent per annum. Screening for the detection of early HIV-1 markers yielded an incidence of 5.0 percent per annum, while estimating incidence from serial cross-sectional prevalence data and clinic recidivists gave estimates of 3.5 percent and 4.5 percent per annum, respectively. These results were found to be internally consistent. Indirect estimates of incidence based on prevalence data can give accurate surrogates of true incidence. Within limitations, even crude measures of incidence are robust enough for health planning and evaluation purposes. For planning vaccine efficacy trails, consistent conservative estimates may be used to evaluate population before targeting them to cohort studies(AU)