Detection of human immunodeficiency virus type 1 (HIV-1) antibody by western blotting and HIV-1 DNA by PCR in patients with AIDS

Western blotting: evolution of an old analytical method to a new quantitative tool for biomarker measurements

Western blotting (WB) is a widely used laboratory technique for detecting specific proteins in biological matrices. Recent advances in antibody production, automation, gel and membrane manufacturing and highly sensitive detection platforms have transformed WB from a labor-intensive and qualitative method into a highly reproducible and quantitative assay suitable for biomarker detection. Despite these significant improvements in the capabilities and efficiency of WB, there remain challenges that hinder its widespread application as a research, diagnostic (in two-tiered assays like Lyme disease testing) and drug development tool. This article describes recent innovations introduced to WB methodology and the remaining challenges that prevent its wider adoption for biomarker measurements throughout the drug development process.

Are HIV-1-Specific Antibody Levels Potentially Useful Laboratory Markers to Estimate HIV Reservoir Size? A Review

Despite the benefits achieved by the widespread availability of modern antiretroviral therapy (ART), HIV RNA integration into the host cell genome is responsible for the creation of latent HIV reservoirs, and represents a significant impediment to completely eliminating HIV infection in a patient via modern ART alone. Several methods to measure HIV reservoir size exist; however, simpler, cheaper, and faster tools are required in the quest for total HIV cure. Over the past few years, measurement of HIV-specific antibodies has evolved into a promising option for measuring HIV reservoir size, as they can be measured via simple, well-known techniques such as the western blot and enzyme-linked immunosorbent assay (ELISA). In this article, we re-visit the dynamic evolution of HIV-1-specific antibodies and the factors that may influence their levels in the circulation of HIV-positive individuals. Then, we describe the currently-known relationship between HIV-1-specific antibodies and HIV reservoir size based on study of data from contemporary literature published during the past 5 years. We conclude by highlighting current trends, and discussing the individual HIV-specific antibody that is likely to be the most reliable antibody for potential future utilization for quantification of HIV reservoir size.

Molecular and Immunological Diagnostic Techniques of Medical Viruses

Viral infections are causing serious problems in human population worldwide. The recent outbreak of coronavirus disease 2019 caused by SARS-CoV-2 is a perfect example how viral infection could pose a great threat to global public health and economic sectors. Therefore, the first step in combating viral pathogens is to get a timely and accurate diagnosis. Early and accurate detection of the viral presence in patient sample is crucial for appropriate treatment, control, and prevention of epidemics. Here, we summarize some of the molecular and immunological diagnostic approaches available for the detection of viral infections of humans. Molecular diagnostic techniques provide rapid viral detection in patient sample. They are also relatively inexpensive and highly sensitive and specific diagnostic methods. Immunological-based techniques have been extensively utilized for the detection and epidemiological studies of human viral infections. They can detect antiviral antibodies or viral antigens in clinical samples. There are several commercially available molecular and immunological diagnostic kits that facilitate the use of these methods in the majority of clinical laboratories worldwide. In developing countries including Ethiopia where most of viral infections are endemic, exposure to improved or new methods is highly limited as these methods are very costly to use and also require technical skills. Since researchers and clinicians in all corners of the globe are working hard, it is hoped that in the near future, they will develop good quality tests that can be accessible in low-income countries.

Screening for human immunodeficiency virus using a newly developed fourth generation lateral flow immunochromatography assay

BACKGROUND

High sensitivity for detection of HIV-1 p24 antigen allows for early detection of primary HIV-1 infections.

OBJECTIVES

To evaluate the detection sensitivity and specificity of the Daina Screen® HIV Combo assay using clinical specimens in Japan where the pretest probability (prevalence) is low.

STUDY DESIGN

We screened 17,373 preoperative outpatient blood samples using 4^th generation lateral flow immunochromatography Daina Screen® HIV Combo assay for simultaneously detecting anti-HIV-1/2 and HIV-1 p24 antigen.

RESULTS

Of the samples tested, 24 were positive for HIV-1 p24 antigen and 49 for HIV-1/2 antibody. Of the 49 samples, 36 were WB and HIV-1 RNA negative, 10 were WB and HIV-1 RNA positive, and 3 were WB positive, HIV-1 RNA negative, and in-house HIV-1 proviral DNA positive. RT-PCR revealed that of the 24 samples that were p24 antigen positive, one sample was HIV-1 RNA positive, which was reconfirmed using an in-house HIV-1 provirus DNA assay. From the 17,300 HIV-1 p24 antigen and anti-HIV-1/2 negative samples, pools containing 10 negative samples each were tested for HIV-1 by RT-PCR; all results were negative.

CONCLUSION

The Daina Screen® HIV Combo assay had a sensitivity and specificity of 100% and 99.7%, respectively, which sufficiently detected HIV infection in the cohort.

Identifying the early post-HIV antibody seroconversion period

BACKGROUND

Identifying persons with recent human immunodeficiency virus (HIV) antibody seroconversion is useful for treatment, research, and prevention, but the sensitivity and specificity of tests for this purpose are uncertain.

METHODS

We used longitudinal specimens panels from 155 persons identified prior to HIV seroconversion to assess antibody-based methods for classifying persons as within 30, 60, or 90 days of seroconversion, including 2 incidence assays, a less-sensitive (LS) enzyme immunoassay (EIA), and the BED assay.

RESULTS

Sensitivity and specificity, respectively, for identifying persons within 30 days of seroconversion were: 34%-57% and 98%-100% for 2 standard EIAs (employing a signal-to-cutoff ≤4.0; ≥1.0 defines HIV positive), 84% and 73% for the LS-EIA (≤0.2 cutoff), 88% and 72% for the BED (≤0.2 cutoff), and 43%-58% and 98% (≤3 bands) for 2 Western blot (WB) assays. By area under the receiver operator curves, the best test for identifying persons within 30 days of seroconversion was the number of bands on the Bio-Rad WB (0.90); within 60 days, the LS-EIA and BED (both 0.85); and for persons within 90 days the BED (0.86).

CONCLUSIONS

Standard EIAs, Western blots, and HIV incidence assays provide useful information for identifying persons 30 to 90 days after seroconversion.

[Ambulatorial prevalence of hepatitis B and C markers in patients with human immunodeficiency virus infection in a general hospital]

BACKGROUND

Hepatitis B and C viruses and human immunodeficiency virus share the same route of transmission, and the prevalence of HBV and HCV infection in patients infected with HIV is greater than it is in the general population.

AIM

To determine the prevalence of hepatitis B and C markers in a population of patients with HIV as well as the risk factors involved.

PATIENTS AND METHODS

From 5,870 registration forms of patients with HIV of an Infectology Unit, 587 were randomly selected. From these, the 343 which had investigated the presence of any hepatitis B (HBsAg, anti-HBc or anti-HBs) or C (anti-HCV) marker were retrospectively analyzed.

RESULTS

HBsAg was positive in 14/306 (4.6%), anti-HBs was positive in 40/154(26.0%), and anti-HBc in 79/205 (38.5%). The anti-HCV test was reactive in 126/330 (38.2%). HBV and HCV co-infection was observed in 7 of the 296 patients who had both HBsAg and anti-HCV tests (2.4%). For those who were HBsAg positive, the main exposure factor was homosexual intercourse (50.0%). For those who were anti-HCV reactive, the main risk factor was intravenous drug use (75.3%). In the HIV mono-infected (185 patients), the most prevalent exposure risk factor was promiscuous heterosexual practices or sexual intercourse with a spouse infected with HIV (83 patients - 44.9%).

CONCLUSION

In our environment HBV-HIV and HCV-HIV co-infections are frequent, a greater relevance being observed in the association between HCV and HIV.

Multistrip Western blotting to increase quantitative data output

The qualitative and quantitative measurements of protein abundance and protein modification states are essential in understanding their role in diverse cellular processes. Traditional Western blotting technique, though sensitive, is prone to produce substantial errors and is not readily adapted to high-throughput technologies. We propose a modified immunoblotting procedure, which is based on simultaneous transfer of proteins from multiple gel-strips onto the same membrane, and is compatible with any conventional gel electrophoresis system. As a result, the data output per single blotting cycle can readily be increased up to ten-fold. In contrast to the traditional "one protein detection per electrophoresis cycle", this procedure allows simultaneous monitoring of up to nine different proteins. In addition to maintaining the ability to detect picogram quantities of protein, the modified system substantially improves data accuracy by reducing signal errors by two-fold. Multistrip Western blotting procedure allows making statistically reliable side-by-side comparisons of different or repeated sets of data. Compared to the traditional methods, this approach provides a more economical, reproducible, and effective procedure, facilitating the generation of large amounts of high-quality quantifiable data.

[Evaluation of the cellular immunity in patients coinfected by the hepatitis C virus and the human immunodeficiency virus]

BACKGROUND

The immune activation provoked by the hepatitis C virus can be deleterious in patients with human immunodeficiency virus, favouring the destruction of CD4 cells. By the other side, the immune restoration observed after the onset of antiretroviral therapy can be partially obscured in patients with the hepatitis C virus.

AIM

The objective of the present study was to evaluate the impact of coinfection by hepatitis C virus and the human immunodeficiency virus in the cellular immunity.

METHODS

Two groups of patients were considered: coinfected patients were prospectively evaluated in the gastroenterology clinic at "Hospital Nossa Senhora da Conceição", Porto Alegre, RS, Brazil (group 1 - 385 patients), and monoinfected patients by human immunodeficiency virus based on the review of the charts from the infectious diseases clinic (group 2 - 198 patients). Demographic (gender, race, age) CD4 and CD8 cell count, CD4/CD8 index and human immunodeficiency virus viral load were evaluated. A 5% significance level was adopted.

RESULTS

There were no difference between the parameters evaluated: mean CD4 count (374,7 +/- 215,7 x 357,5 +/- 266,0), CD8 (1.512,4 +/- 7.274,6 x 986,7 +/- 436,4) and HIV viral load (83.744,2 +/- 190.292,0 x 104.464,0 +/- 486.880,5) respectively in both groups evaluated, as well as the proportion of patients with CD4/CD8 rate below 1.

CONCLUSION

Coinfection by both viruses did not have a negative impact in relation to monoinfection by human immunodeficiency virus, and the immune profile was similar in all groups.

Simple DNA extraction method for dried blood spots and comparison of two PCR assays for diagnosis of vertical human immunodeficiency virus type 1 transmission in Rwanda

Dried blood spots (DBS) on filter paper facilitate the collection, transport, and storage of blood samples for laboratory use. A rapid and simple DNA extraction procedure from DBS was developed and evaluated for the diagnosis of human immunodeficiency virus type 1 (HIV-1) infection in children by an in-house nested-PCR assay on three genome regions and by the Amplicor HIV-1 DNA prototype assay version 1.5 (Roche Molecular Systems). A total of 150 samples from children born to HIV-1-infected mothers were collected in Kigali, Rwanda, in parallel as DBS and as peripheral blood mononuclear cell (PBMC) pellets. The results obtained on DBS by the two PCR assays were compared to the results of nested PCR on PBMCs. Of 150 PBMC samples, 10 were positive, 117 were negative, and 23 were indeterminate for HIV-1 infection. In DNA extracted from filter papers and amplified by using the in-house nested PCR, 9 of these 10 positive samples (90%) were found to be positive, and 1 was found to be indeterminate (only the pol region could be amplified). All of the negative samples and all of the 23 indeterminate samples tested negative for HIV-1 infection. When we used the Amplicor DNA test on DBS, all of the 10 PBMC-positive samples were found to be positive and all of the 23 indeterminate samples were found to be negative. Of the PBMC-negative samples, 115 were found to be negative and 2 were found to be indeterminate. We conclude that this simple rapid DNA extraction method on DBS in combination with both detection methods gave a reliable molecular diagnosis of HIV-1 infection in children born to HIV-infected mothers.

Sup35p yeast prion-like protein as an adapter for production of the Gag-p55 antigen of HIV-1 and the L-chain of botulinum neurotoxin in Saccharomyces cerevisiae

Effective expression of the HIV-1 core protein Gag-p55 was obtained in Saccharomyces cerevisiae under control of the inducible UASgal/CYC1 promoter as a translational fusion with the prion-forming NM domain of the translation terminator Sup35p (eRF3) of S. cerevisiae. where only poor expression of the original-type Gag-p55 was observed. A deletion within the Sup35NM prion-forming domain altering Sup35-associated [PSI] inheritance did not compromise expression of the Sup35NM Gag-p55 fusion protein. Therefore, either the mechanism of this phenomenon is not directly related to the effect of Sup35p prion-formation or the modified protein maintains residual prion-forming abilities. The recombinant Sup35p-Gag-p55 protein was quite stable under boiling in an alkali/sodium dodecyl sulfate (SDS) solution and completely retained its antigenic properties. Moreover, 10-min boiling of the native yeast cells in this solution allowed immediate inhibition of lysosomal and other yeast proteases, responsible for autolysis of many natural and recombinant proteins. The use of this method of preliminary enrichment for the recombinant fusion protein Sup35p-Gag-p55 with the SDS-alkaline extraction could be useful for yeast heterologous expression and purification of other of insoluble and unstable proteins. A translational fusion with the NM domain of Sup35p was also used to produce another poorly soluble protein, the L-chain of botulinum exotoxin A, in S. cerevisiae. When the Sup35p fragment was removed from the recombinant construct encoding a fused Sup35/BoNT protein, a dramatic drop in both transformation efficiency and growth rate of transformants was shown.

Optimization of polymerase chain reaction for detection of HIV type 2 DNA

The aim of this study was to increase the sensitivity of an earlier version of an HIV-2 nested PCR assay based on primers in the gag, pol, LTR, and env regions. The assay was first optimized with regard to concentrations of dNTP, MgCl2, and primers, using a method that allowed optimization of all three parameters in only two test runs. We then designed and optimized new primer sets in the LTR, gag, and gag/pol regions that were based on more isolates than were the former (old) primer sets. Samples from 57 HIV-2 antibody-positive individuals were tested with the four old primer sets as well as with the three new primer sets. Five primer sets from this run (new gag, new gag/pol, old LTR, old env, and new LTR) were then tested with 35 more samples, giving a total number of 92 tested samples from HIV-2-infected individuals. At initial testing of the 92 samples a combination of primer sets from two different regions yielded a sensitivity ranging from 93.5 to 98.9%. After repeated testing the sensitivity ranged from 96.7 to 100% for the different primer combinations. The specificity was 100% for all primer sets except old LTR, which had a specificity of 97%. In conclusion, it is possible to create a more sensitive PCR assay by optimizing the different PCR parameters as well as by including primer sets based on more isolates.