The Evolution of HIV Diagnostic Testing

Published

1 year ago

December 16, 2024

admin

By Dr. Priyom Bose, Ph.D. Reviewed by Danielle Ellis, B.Sc.

What happens after HIV infection?
Evolution of HIV diagnostic assays
Conclusions
References
Further reading

Acquired immunodeficiency syndrome (AIDS) is caused by the human immunodeficiency virus (HIV) that attacks the body’s immune system, making it vulnerable to all infections. One of the major concerns of the early AIDS epidemic that began in 1981 was the lack of proper diagnostic measures to identify infected individuals.1 Since the development of the first HIV diagnostic assay in 1985, scientists have continued to improve diagnostic accuracy, detection speed, and cost.

Image Credit: Hanna Karpiak/Shutterstock.com What happens after HIV infection?

The immune system produces antibodies after encountering harmful foreign substances or antigens. HIV infects the vital cells associated with immunity, such as macrophages, helper T cells, and dendritic cells, and disrupts their function. The three important HIV antigens are p24, gp 41, and gp 120.2

HIV is a slow-replicating retrovirus that is transmitted through sexual intercourse, sharing an infected needle, or by blood transfer.3 After HIV infection, the viral load cannot be measured immediately due to low plasma load. Typically, the viral RNA can be measured within 10 to 12 days after infection.4

Antibodies to p24 and gp 41 are the first serological markers used to detect HIV infection. IgG antibodies appear approximately three weeks after infection. In the majority of HIV-infected individuals, HIV antibodies appear to circulate within 1 to 2 months of the infection. However, in a few cases, it may take up to six months to appear at a detectable level.5 Evolution of HIV diagnostic assays

Over the years, scientists have developed many immunoassays and nucleic acid amplification tests (NAATs) to accurately and high-throughput HIV diagnosis. These tests are broadly divided into two categories, namely, screening and confirmatory tests. Typically, HIV tests are performed on blood, oral fluids, or urine samples.6

HIV screening is performed by various immunoassays that focus on detecting IgG antibodies against HIV-1 antigens in the serum. Techniques such as Western blot, line immunoassay (LIA), and recombinant immunoblot are used as confirmatory tests.7 Some of the important HIV diagnostic assays are discussed below: Serological testing for HIV

In the mid-1980s, simple serological tests for HIV antibodies were developed based on culture-derived viral antigen preparation.7 These tests enabled HIV diagnosis and assessed blood and blood product supplies. Since the early assays, various serological assays have been developed that aided simple/rapid testing, high-throughput screening, confirmatory tests, incidence determination, and epidemiological surveillance. Since its first development, five generations of enzyme immunoassays (EIAs) have emerged based on varied antigen preparations and detection chemistries.8

First-generation assays: The first-generation EIAs detect IgG antibodies from antigens derived from whole viral lysates of HIV-positive cultures. Since crude antigen lysate contains impurities, this method exhibited reduced specificity and high false positivity. In contrast, immunofluorescence assays or Western blotting (WB) have shown higher specificity and lower false positivity.

Second-generation assays: Second-generation assays involve the use of recombinant proteins or synthetic peptides derived from the immunodominant regions (IDR) of HIV-1 proteins and gp36 of HIV-2, which increases sensitivity and decreases false positivity.

Third-generation assays: Third-generation assays, including the Genetic Systems HIV-1/HIV-2 Plus O EIA, use a variety of antigens to detect HIV-1 and -2 antibodies in the serum. A major advantage of third-generation sandwich format assays is their ability to detect HIV-1 IgM antibodies early, enabling quicker HIV diagnosis.

Fourth-generation assays: The fourth-generation EIAs, including the Abbott Architect HIV Ag/Ab Combo assay, utilize fully automated chemiluminescent microparticle technology that can instantaneously identify antibodies to HIV-1 and HIV-2 and HIV-1 p24 antigen. This technique has further allowed early HIV diagnosis. Other advantages of fourth-generation high-throughput assays are their capacity to perform more than 150 tests per hour and their ability to test specimens immediately upon arrival and generate results within 30 minutes. These assays are suitable for facilities, such as blood banks, that handle high volumes of blood samples.

Fifth-generation assays: Fifth-generation assays, such as the Bio-Rad BioPlex 2200 HIV Ag-Ab assay, use magnetic beads coated with p24 monoclonal antibodies and epitopes specific for HIV-1 and HIV-2. This type of assay has a major advantage in that it can confirm HIV infection in a single test. Interested in Assay Kits? Explore Equipment Here

Despite the advancements in EIA assays, the challenges associated with the generation of false positive results persist. Therefore, EIA-reactive specimen is typically retested with supplemental tests, such as Western Blot. Rapid diagnostic tests Related StoriesSweden exceeds UNAIDS HIV goals but faces new challengesNutrition's pivotal role in combating tuberculosis: addressing N-AIDS for better outcomes

The first HIV rapid test was available in the early 1990s. It determined an individual's serostatus before surgery, maternal labor/delivery, and organ transplant. Rapid diagnostics is based on immunochromatographic technology that uses blood from finger pricks to assess HIV status. 9 This test can provide results in less than 30 minutes and can be used in point-of-care (POC) settings. Since this test presents both false positive and negative results, it is essential to confirm the findings with laboratory-based HIV assays.

The main advantage of this technique is that any non-laboratory staff can perform it in a primary health care center. Even though decentralization of HIV diagnostic services has increased HIV test service in remote areas, it has been challenged by the lack of national guidelines, waste disposal, inventory management, and quality assurance (QA) monitoring.10

HIV self-testing, based on rapid testing methods, has allowed individuals who would otherwise refrain from testing in fear of discrimination to perform the test privately and start proper intervention. The World Health Organization (WHO) has prequalified several HIV rapid tests for HIV self-testing, including the Insti HIV-1/HIV-2 antibody tests and the Oraquick rapid HIV-1/2 antibody test.10 Nucleic acid test (NAT)

The NAT identifies HIV nucleic acid, i.e., either RNA or proviral DNA, in the blood sample. This test is based on the principles of polymerase chain reaction (PCR), nucleic acid sequence-based amplification, or ligase chain reaction.11 This test has proved to be vital in situations when an antibody against HIV is absent in serum. NAT is also performed in newborns of HIV-infected mothers. Unlike other assays, this test can detect HIV even after recent or possible exposure to the virus. Furthermore, NAT can quantify viral load.

Revolutions in Infectious Disease Testing Conclusions

The advancements in HIV diagnostic assays have played a vital role in identifying, staging, and monitoring infected individuals, even when they are under antiretroviral therapy. These assays have played an important role in surveillance and identification of transmission hot spots. Extraordinary progress in HIV testing methodologies has not only reduced false positives but decreased assessment time as well. References Sharp PM, Hahn BH. Origins of HIV and the AIDS pandemic. Cold Spring Harb Perspect Med. 2011;1(1):a006841. doi: 10.1101/cshperspect.a006841. Foster JE., et al. Viruses as Pathogens: Animal Viruses, With Emphasis on Human Viruses. Viruses. 2018; 157-187. doi.org/10.1016/B978-0-12-811257-1.00007-3 Dasgupta A, Wahed. Human immunodeficiency virus (HIV) and hepatitis testing. Clinical Chemistry, Immunology and Laboratory Quality Control (Second Edition). 2021; 513-533. doi.org/10.1016/B978-0-12-815960-6.00015-7 Konrad BP, et al. On the duration of the period between exposure to HIV and detectable infection. Epidemics. 2017; 20, 73-83. doi.org/10.1016/j.epidem.2017.03.002 Davis LE. Acute viral meningitis and encephalitis. Infections of the Nervous System, 1987; 156-176. doi.org/10.1016/B978-0-407-02293-5.50014-3 Pant PN. Oral fluid-based rapid HIV testing: issues, challenges and research directions. Expert Review of Molecular Diagnostics. 2007; 7 (4), 325-328, DOI: 10.1586/14737159.7.4.325 Abdullah DM, et al. The contemporary immunoassays for HIV diagnosis: a concise overview. Asian Biomed (Res Rev News). 2023;17(1):3-12. doi: 10.2478/abm-2023-0038. Alexander TS. Human Immunodeficiency Virus Diagnostic Testing: 30 Years of Evolution. Clin Vaccine Immunol. 2016;23(4):249-53. doi: 10.1128/CVI.00053-16. Aidoo S, et al. Suitability of a rapid immunochromatographic test for detection of antibodies to human immunodeficiency virus in Ghana, West Africa. J Clin Microbiol. 2001;39(7):2572-5. doi: 10.1128/JCM.39.7.2572-2575.2001. Parekh BS, et al. Diagnosis of Human Immunodeficiency Virus Infection. Clin Microbiol Rev. 2018;32(1):e00064-18. doi: 10.1128/CMR.00064-18. Garrett, P. E. Quality control for nucleic acid tests: Common ground and special issues. Journal of Clinical Virology. 2001; 20(1-2), 15-21. doi.org/10.1016/S1386-6532(00)00150-5

Further ReadingAll HIV ContentThe Economic Impacts of AIDSRecent Advancements in Treating HIV

Last Updated: Nov 29, 2024

World

Vladimir Putin’s spymaster ‘has telephone call with MI6 chief’ as EU leaders meet to discuss Ukraine funding

Published

1 hour ago

December 19, 2025

admin

Vladimir Putin's spymaster 'has telephone call with MI6 chief' as EU leaders meet to discuss Ukraine funding

Vladimir Putin’s spymaster has said he had a “rather lengthy telephone conversation” with the new head of MI6, Russian state news agency Tass has reported.

Sergei Naryshkin, Russia’s foreign intelligence director, said: “A few days ago, I had a rather lengthy telephone conversation with the newly appointed chief of MI6 [Blaise] Metreweli.”

He added that Russian intelligence officers worked officially in London while MI6 officers worked officially in Moscow, according to Tass.

Ms Metreweli took over as chief of the Secret Intelligence Service on 1 October.

Sky News military analyst Michael Clarke believes it shows Moscow is “trying to imply that the Brits are somehow appealing to them… because of the negotiations going on in Washington”.

Further US-Russia talks are expected to take place over the coming days.

EU talks stall amid fears over ‘Russian retaliation’

Mr Naryshkin’s comments came as the European Union held crunch talks on Ukraine funding in Brussels.

EU leaders met at the bloc’s headquarters on Thursday to discuss a plan to use frozen Russian assets – but tensions have arisen, with Belgium vocally opposed to the plan amid fears of Russian retaliation.

Most of the €190bn (£166bn) of assets frozen after the start of the war in 2022 are currently held in Belgium, specifically by Euroclear, the Brussels-based financial clearing house.

Belgium’s Prime Minister Bart De Wever said the plan to loan Ukraine the frozen assets “drastically increases the risk of Russian retaliation”.

“It’s not acceptable that this happens to Belgium alone,” he added. “If we jump, we jump together.”

Ukraine’s President Volodymyr Zelenskyy said he understands “the risks that he is talking about, but I think that we face bigger risks”.

“Ukraine has the right to this money because Russia is destroying us,” Mr Zelenskyy said.

In a post on X, he added: “The decision now on the table – the decision to fully use Russian assets to defend against Russian aggression – is one of the clearest and most morally justified decisions that could ever be made.”

Trump claims peace deal is ‘close’

On the other side of the Atlantic, Donald Trump has been pressuring Ukraine to move quickly to secure a peace deal.

The US president’s envoys are scheduled to meet with a top adviser to Mr Putin in Miami on Saturday, where they are due to discuss the evolving US peace agreement aimed at ending the war.

Mr Trump has been optimistic that a deal can be reached.

“Well, we’re getting close to something, but I hope Ukraine moves quickly because Russia is there,” he said. “Every time they take too much time, Russia changes their mind.”

Russia ‘deploys nuclear-capable missiles’ to Belarus

Russia has deployed its latest nuclear-capable missile system to Belarus according to the country’s president, Alexander Lukashenko.

The authoritarian leader said the Oreshnik, an intermediate range ballistic missile system, arrived in the country on Wednesday and is entering combat duty.

He did not provide any further details.

Russia has previously deployed tactical nuclear weapons to Belarus, the territory of which it used to launch the full-scale invasion of Ukraine in February 2022.

World

Democrats release more Epstein photos – with crucial deadline now just hours away

Published

1 hour ago

December 19, 2025

admin

Democrats release more Epstein photos - with crucial deadline now just hours away

Democrats have shared more pictures from Jeffrey Epstein’s estate, a day before the government’s deadline for the full release.

The 68 photos published on Thursday are among more than 95,000 images that the House Oversight Committee Democrats said they were reviewing.

They said the images were “selected to provide the public with transparency into a representative sample of the photos” and to “provide insights into Epstein’s network and his extremely disturbing activities”.

But the Democrats added that they are still analysing thousands more images that are “both graphic and mundane”.

There is no suggestion of wrongdoing on the part of those pictured in the images – and the context surrounding the photos is not known.

Mystery text quotes price for ‘girl’

The latest cache includes a text message appearing to discuss the price for a girl.

It isn’t clear who sent the messages and to whom, but the screenshot shows some details on an unidentified girl, described as a teenager here.

“I will send u girls now,” one of the texts read.

Writing on body

Several pictures show handwritten messages on a person’s body.

One appears to be quoting the opening paragraph of the book Lolita – which can be seen in the background of the picture.

The book was written by Vladimir Nabokov and tells the story of a girl groomed by a middle-aged literature professor.

Another shows writing on a foot, which reads: “She was Lo, plain Lo, in the morning, standing four feet ten in one sock.”

Other messages can be seen on the neck, hip, back and chest, with the latter reading: “The tip of the tongue taking a trip of three steps down”.

In a different image, Epstein is pictured with three girls in his house in New York. One appears to be touching Epstein’s chest, one is holding her wrist up and another is looking at a laptop.

The identity of the women has been hidden.

Epstein with high-profile figures

Some high-profile figures also appear in the newly released images, with one showing Epstein sitting alongside Sheikh Jabor Bin Yousef Bin Jassim Bin Jabor al Thani.

He is the chairman and director of several privately established companies and is a member of the Qatari royal family.

Another image shows Epstein with the former president of the UN General Assembly, Miroslav Lajcak, who held the role between 2017 and 2018. He is also a former Slovakian foreign affairs minister.

Last month, he told TASR news agency: “The reopening of the Epstein case occurred after I left New York, and the full extent of his inexcusable actions, which I strongly condemn, only came to light after his arrest.”

Shaher Abdulhak, a deceased Yemeni billionaire businessman whose son is a suspect in the murder of a Norwegian woman in Mayfair, was also pictured with Epstein.

His son, Farouk Abdulhak, fled to Yemen after the rape and death of Martine Vik Magnussen in March 2008 and has been wanted for questioning ever since.

Ms Magnussen was found dead among rubble in a basement in Great Portland Street.

She and her friends had been celebrating finishing their end-of-term exams at the Maddox nightclub before she vanished. Her body was found two days later.

Also featured in the newly released images were former Israeli prime minister Ehud Barak, magician David Blaine, businessman Tom Pritzker, billionaire Bill Gates, director Woody Allen, talk show host Dick Cavett, Trump ally Steve Bannon, and Kuwait’s former information minister Anas al Rasheed.

Photos of identity documents with redacted names were also published, including one with text saying that “the bearer was convicted of a sex offense against a minor”, which could belong to convicted sex offender Epstein.

Also among the identification documents is a heavily redacted Russian passport. It belongs to a female, but other information has been blocked out.

The release also includes ID documents from the Czech Republic, South Africa, Ukraine, and Lithuania.

Deadline looming

The picture drop came a day before the deadline set by a bipartisan bill that compels the US Justice Department to release the Epstein files within 30 days, which was signed into law by US President Donald Trump last month.

Mr Trump had promised to release the Epstein files during his ultimately successful presidential campaign, but he later made a U-turn, even going as far as calling the Epstein files a Democratic “hoax”, before eventually changing path again to sign the bill.

House minority leader Hakeem Jeffries said ahead of the deadline that he believes the Department of Justice will release the files in time, and warned that there will be “strong bipartisan pushback” if they don’t.

“Based on my conversations with some of the top Democrats who’ve been working on this matter, related to full and complete disclosure of the Epstein files, we do expect compliance,” he told reporters on Thursday.

Full release going ‘down to the wire’

National security lawyers inside the Department of Justice are “working down to the wire” as Friday’s deadline for the full release of the Epstein files edges closer, according to Sky News’ US correspondent James Matthews.

He said those lawyers are mulling “how much is actually divulged in these documents”.

“There will be redactions… the question is, how far short of everything? How far short of the full story will the release fall?” Matthews said.

“The issue at the heart of it… where does Donald Trump feature? Remember, he emphatically denies all knowledge of Epstein’s criminal activities and any involvement in them.”

‘Frustration building’

Meanwhile, frustration is building at the justice department ahead of the release, according to CNN.

A source has told the US broadcaster that there could be up to 1,000 redactions needed from each attorney.

Lawyers reportedly believe they aren’t getting clear or comprehensive direction on how to make the most information available under the law.

A previous batch of images featured more high-profile figures, including Donald Trump, Andrew Mountbatten-Windsor, Bill Clinton, British entrepreneur Richard Branson, Emirati businessman Ahmed bin Sulayem, and singer Jimmy Buffett.

Several images of a sexual nature have also been released, including a picture of a bowl of novelty condoms with a caricature of Mr Trump’s face, and various sex toys.

US