HIV-1 antibody testing strategy: evaluation of ELISA screening and western blot profiles in a mixed low risk/high risk patient population

HIV serologically indeterminate individuals: Future HIV status and risk factors

BACKGROUND

Indeterminate HIV test results are common, but little is known about the evolution of indeterminate serology and its sociodemographic and behavioral correlates. We assessed future HIV serological outcomes for individuals with indeterminate results and associated factors in Rakai, Uganda.

METHODS

115,944 serological results, defined by two enzyme immunoassay (EIAs), among 39,440 individuals aged 15-49 years in the Rakai Community Cohort Study were assessed. Indeterminate results were defined as contradictory EIAs. Modified Poisson regression models with generalized estimating equations were used to assess prevalence ratios (PRs) of subsequent HIV serological outcomes and factors associated with HIV indeterminate results.

RESULTS

The prevalence of HIV serologically indeterminate results was 4.9%. Indeterminate results were less likely among women than men (adjPR 0.76, 95% CI 0.71,0.81), in unmarried participants than married participants (adjPR 0.92, 95% CI 0.85,99), and in individuals with primary (adjPR 0.90, 95% CI 0.80,1.02), secondary (adjPR 0.83, 95% CI 0.73,0.96) and post-secondary (adjPR 0.75, 95% CI 0.60,0.94) education, relative to no education. The proportions of persons with indeterminate results progressing to HIV positive, negative or indeterminate results in subsequent visits was 5%, 71% and 24%, respectively.

CONCLUSION

HIV serologically indeterminate results were associated with gender and marital status. HIV surveillance programs should develop a protocol for reporting individuals with mixed or persistently indeterminate HIV results on multiple follow-up visits. Most indeterminate results became HIV-negative over time, but follow-up is still needed to detect positive serologies.

Human immunodeficiency virus in cadavers: A review

Millions of people are infected with human immunodeficiency virus (HIV); however, limited research focuses on post-mortem HIV detection. Post-mortem HIV testing is vital because medical records are not always available, and the HIV status can be unknown. The aims of this study were to review the available literature and determine the most efficient HIV test for post-mortem samples, the optimal tissue or bodily fluid to be tested, and the duration that HIV remains reliably detectable. A literature search was conducted using PubMed and Google Scholar. Terms were related to HIV (HIV detection, HIV testing, HIV prevalence) and deceased individuals (post-mortem, cadaver, deceased, organ donor). Inclusion criteria included English studies, or articles with at least an English abstract, while review articles were excluded. From this literature search, 43 studies were applicable. These studies most commonly used enzyme-linked immunosorbent assay and Western blot as screening and confirmation tests, respectively. As for the optimal tissue or bodily fluid, serum remained the golden standard, while testing skin seemed promising. HIV remains detectable in the body up to 58 days after death, although few studies tested samples after 48 h. Knowledge of the HIV status can be beneficial in the case of accidental exposure and can create a range of possible research opportunities on the effects of HIV in different organ systems. This review outlined several gaps in the current literature and future studies should investigate these gaps because this information can be relevant to numerous professions. Clin. Anat. 32:603-610, 2019. © 2019 Wiley Periodicals, Inc.

Seroprevalence of blood-borne infections and population sizes estimates in a population of injecting drug users in Croatia

Similar to some other Central European countries, Croatia has low HIV prevalence among injecting drug users (IDUs) but high hepatitis C (HCV) prevalence. This may indicate different patterns of risk behaviour in this region than in other parts of Europe. The main objectives of this study were to assess the seroprevalence of HIV and hepatitis B and C and related risk factors among IDUs in the three largest Croatian cities (Zagreb, Split, Rijeka) and within the national prison system, as well as to apply a multiplier-method population size estimation of IDUs in Zagreb, Split and Rijeka. Recruitment sites were selected in collaboration with the local public health institutes, NGOs, Centers for treatment municipalities and the judiciary system. Participants were recruited during September and October 2007. Trained peer-recruiters were used to recruit IDU participants at treatment and harm reduction centres as well as pre-identified social, commercial and street based venues. Participants completed the study questionnaire and provided venous blood samples for HIV, hepatitis B and hepatitis C testing. The study included 601 participants, of whom 121 were recruited in Split, 130 in Zagreb, 150 in Rijeka and 200 in the prison system. The prevalence of positive anti-HCV tests was 65% in Split, 51% in Zagreb, 29% in Rijeka and 44% in the prisons. The prevalence of anti-HBcAg was 31% in Split, 13% in Zagreb, 9% in Rijeka and 24% in prison. No case of HIV infection was found. The estimated IDUs population sizes were 2,805 for Zagreb area, 3,347 for Split and 1,370 for Rijeka area, however confidence intervals were very large, indicating the need for larger samples. A high frequency of positive markers on hepatitis B virus and C virus in the population of injecting drug users in Croatia has been confirmed with this research, as well as a low prevalence of HIV infection. This may be related to relatively low levels of injecting risk behaviour and injecting frequency although it is not possible to make strong conclusions on risk behaviour, as participants were mostly recruited in harm reduction programmes. This research should be followed by targeted activities for reducing risks of infectious diseases among injecting drug users in the Republic of Croatia and future research at the national level.

Evidence of HIV exposure and transient seroreactivity in archived HIV-negative severe hemophiliac sera

Background

Approximately 25% of hemophiliacs that were frequently exposed to blood clotting factor concentrates (CFCs) contaminated with human immunodeficiency virus (HIV) are presently HIV seronegative. In this study, we sought to determine if some of these individuals were at any time transiently HIV seropositive. In the early to mid-1980s the majority of severe hemophilia patients were exposed to CFCs contaminated with HIV. Although many of these hemophiliacs became HIV-positive, a small percentage did not become infected. To determine if some of these individuals successfully resisted viral infection, we attempted to document the presence of transient HIV reactive antibodies in archived plasma samples (1980–1992) from currently HIV-negative severe hemophiliacs who had a high probability of repeated exposure to HIV contaminated CFC. Archived plasma samples were retrospectively tested using an FDA approved HIV-1Ab HIV-1/HIV-2 (rDNA) enzyme immunoassay (EIA) and a HIV-1 Western blot assay (Wb), neither of which were commercially available until the late 1980s, which was after many of these samples had been drawn.

Results

We found that during the high risk years of exposure to HIV contaminated CFC (1980–1987), low levels of plasma antibodies reactive with HIV proteins were detectable in 87% (13/15) of the haemophiliacs tested. None of these individuals are presently positive for HIV proviral DNA as assessed by polymerase chain reaction (PCR).

Conclusion

Our data suggest that some severe hemophiliacs with heavy exposure to infectious HIV contaminated CFC had only transient low-level humoral immune responses reactive with HIV antigens yet remained HIV-negative and apparently uninfected. Our data supports the possibility of HIV exposure without sustained infection and the existence of HIV-natural resistance in some individuals.

Higher western blot immunoreactivity of glycoprotein 120 from R5 HIV type 1 isolates compared with X4 and X4R5 isolates

The envelope glycoprotein of human immunodeficiency virus 1 (HIV-1) plays important roles in viral life cycle and pathogenesis. Understanding the immune responses the protein elicits during the course of a viral infection in patients is important in designing an effective vaccine candidate against the virus or for better diagnosis of the disease. In this study, we report that gp120 of R5 isolates have higher Western blot (WB) immunoreactivity to antibodies elicited against the protein in virus-infected human patients compared with that of X4 and X4R5 isolates. Analyses of WB immunoreactivity of chimeric gp120s constructed between R5 (AD8) and X4R5 (DH12) HIV-1 isolates indicate that there are complex tertiary interdomain interactions even after a complete denaturation of the protein. Our data suggest that the determinant(s) responsible for the high WB immunoreactivity might be present in all gp120s, but are accessible to antibodies only for R5 gp120s in the WB assay. The V1/V2 and/or V3 regions of X4 and X4R5 gp120s likely interfere with either the formation or surface exposure of the WB immunoreactive determinant. Supplementing HIV-1 WB diagnosis kits with purified R5 gp120 could improve their sensitivity and facilitate earlier diagnosis of virus infection.

Immune complex transfer enzyme immunoassay that is more sensitive and specific than western blotting for detection of antibody immunoglobulin G to human immunodeficiency virus type 1 in serum with recombinant pol and gag proteins as antigens

Antibody immunoglobulin G (IgG) to human immunodeficiency virus type 1 (HIV-1) in serum was detected by ultrasensitive enzyme immunoassays (immune complex transfer enzyme immunoassays) with recombinant reverse transcriptase (rRT), p17 (rp17) and p24 (rp24) of HIV-1 as antigens and beta-D-galactosidase from Escherichia coli as the label. The immune complex, comprising 2,4-dinitrophenyl-bovine serum albumin-recombinant protein conjugate, antibody IgG to HIV-1, and recombinant protein-beta-D-galactosidase conjugate, was trapped on polystyrene beads coated with affinity-purified (anti-2,4-dinitrophenyl group) IgG, eluted with epsilon N-2,4-dinitrophenyl-L-lysine, and transferred to polystyrene beads coated with affinity-purified (anti-human IgG gamma-chain) IgG. Bound beta-D-galactosidase activity was assayed by fluorometry. The assays were highly reproducible with no serious serum interference, and they were much more sensitive than Western immunoblotting for the corresponding antigens. Signals with rRT, rp17, and rp24 for asymptomatic carriers were at least 56,000-, 680-, and 22-fold higher, respectively, than those for seronegative individuals, and neither indeterminate nor false-positive results were observed, whereas some serum samples were false negative or false positive by Western blotting for p17 and/or p24 antigen. In some cases, seroconversion was detected earlier than by conventional methods. Therefore, these assays are suggested to be more useful than conventional methods not only for the confirmation of antibody IgGs to RT, p17, and p24 of HIV-1 in serum but also for the detection of seroconversion.

Direct detection of proviral gag segment of human immunodeficiency virus in peripheral blood lymphocytes by colorimetric PCR assay as a clinical laboratory tool applied to different at-risk populations

We used a colorimetric polymerase chain reaction (PCR)-based assay in kit form to detect directly human immunodeficiency virus type 1 (HIV-1) proviral gag sequences in peripheral blood cells from 68 healthy blood donors, 51 subjects at risk for HIV infection, 122 patients with HIV-1 infection, 11 patients with indeterminate Western blot (immunoblot) results, 4 blood donors HIV-1 positive by enzyme immunoassay, and 13 children born to HIV-1-seropositive mothers. The results obtained in the blood donors and HIV-1-infected patients demonstrated the high degree of diagnostic specificity and sensitivity of the PCR method. HIV-1 infection was excluded in 10 of the 11 patients with indeterminate Western blot results and in all four enzyme immunoassay-positive blood donors. A diagnosis of HIV infection was ruled out by negative PCR results in 5 of 13 children from seropositive mothers, which excluded vertical transmission of the infection in these cases; these children were younger than 3 months and had positive serological results. Two at-risk patients with negative serological results had positive PCR results. All results were confirmed by conventional PCR. In conclusion, colorimetric PCR, which is commercially available in kit form, is an easy and reliable technique that can be used to detect proviral HIV-1 genomes in blood cells, and despite the limitations owing to HIV genome variability, it is useful in the clinical setting for the diagnosis of HIV infection in selected categories of patients.

A new capture test using conjugated peptides for the detection of HIV antibodies

A new capture test utilizing conjugated peptides has been developed for the detection of antibodies elicited against HIV-1. Human sera diluted 1:1000 were incubated in ELISA plates precoated with protein G. The captured IgG were allowed to react with three synthetic peptides corresponding to the gp41 sequence (591-611) YLKDQQLLGIWGCSGKLICTT, the gp120 sequence (314-329) IRIQRGPGRAFVTIGK and the p27 sequence (182-198) EWRFDSRLAFHHVAREL. The peptides were used in the form of N-hydroxysuccinimido-biotin ovalbumin conjugates. Peroxidase-labelled streptavidin was used to detect antigen-antibody complexes. The sensitivity and specificity of detection of antibodies were analyzed with 40 HIV positive sera, 10 seroconverting sera and 21 normal human sera (NHS). The results were compared with a commercial indirect ELISA in which a single conjugated gp41 peptide was used as antigenic probe. This indirect ELISA recognized 100% of the HIV positive and the seroconverting sera. The new capture test using the gp41 conjugated peptide also recognized 100% of the HIV positive sera but was more specific since it gave no false positive results whereas the indirect test did. The gp120 and p27 conjugated peptides detected 35/40 (87.5%) and 31/40 (77.5%) of HIV positive sera respectively and also detected 9/10 (90%) and 10/10 (100%) of the seroconverting sera respectively, without any false positive results (0/21). The proposed new capture test is a very sensitive and specific assay for detecting HIV antibodies.

Factors associated with clinical and sub-clinical anal human papillomavirus infection in homosexual men

OBJECTIVES

(I) to determine the relative sensitivities of clinical examination, cytology and HPV DNA hybridisation for the detection of anal human papillomavirus infection; and (ii) to examine various factors which may influence presentation of anal human papillomavirus infection in homosexual men.

METHODS AND RESULTS

112 unselected homosexual men attending a Sydney STD clinic for routine screening underwent a complete anogenital and physical examination, during which blood samples (for haematological, serological and immunological investigations), rectal swabs (for culture of anal pathogens) and anal scrapes of the dentate line (for cytology and HPV DNA hybridisation) were collected. Papanicolaou-stained anal smears were examined for cytological abnormalities, including those indicative of HPV infection or anal intraepithelial neoplasia (AIN). HPV DNA was detected by high stringency dot hybridisations using radiolabelled HPV 6, 11, 16 and 18 DNA probes. Visible anal condylomata, situated either externally or in the anal canal, were present in 26% of these men; 46% had cytological evidence of HPV infection, and 19% of the smears showed evidence of mild to moderate dysplastic changes (AIN I-II). Detectable HPV DNA was present in 40% of the anal scrapes. By combining these results, a total of 73 men (65%) were found to have at least one of the indicators of HPV infection. These data, together with that relating to HIV antibody, immune status and past or present infection with other STDs, was correlated with information obtained from a questionnaire administered to the patients at the time of their clinical examination.

CONCLUSIONS

In this study cytology was found to be slightly more sensitive than HPV DNA dot hybridisation for the detection of HPV infection in the anal canal, providing the full range of HPV-associated cytological changes were accepted as a basis for diagnosis. Clinical anal lesions were more likely to be detected in young men, men who had symptomatic HIV infection and those with a history of past anal wart infection. The latter group also had a higher incidence of cytologically apparent HPV infection in their anal smears. There was a significant association between the detection of HPV 16/18 and the presence of anal dysplasia, but there were no significant correlations between HPV infection or anal dysplasia and HIV antibody, immune function status, sexual practices or history of other STDs.