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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

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Musk appears with black eye at White House farewell – as Trump says he’s ‘not really leaving’

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Musk appears with black eye at White House farewell - as Trump says he's 'not really leaving'

Elon Musk has formally left his role in Donald Trump’s administration.

Mr Musk sported a black eye at a press conference with Mr Trump in which the president confirmed the tech billionaire’s expected departure on Friday.

The billionaire owner of Tesla, SpaceX, and X said his five-year-old son X Æ A-12, or X for short, was responsible for the bruising.

“I was horsing around with my son… I said ‘go ahead and punch me in the face’, and he did,” Mr Musk told reporters in the Oval Office.

“It turns out a five-year-old can punch, actually. I didn’t really feel much at the time.”

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Musk sported a black eye

At the press conference, Mr Trump thanked Mr Musk “for his incredible service” with his work for his help setting up and running the Department of Government Efficiency, or DOGE, and suggested he would continue to be “back and forth”.

The US president handed Mr Musk a golden key in a White House-branded box, which he described as a “special present”.

“Elon gave an incredible service. [There is] nobody like him. And he had to go through the slings and the arrows, which is a shame, because he is an incredible patriot,” Mr Trump said.

“Some of the media organisations in this room are the slingers,” Mr Musk said when asked about the “slings and arrows” in an apparent dig at The New York Times.

The US president praised Mr Musk as “one of the greatest business leaders and innovators the world has ever produced”, commending him for “stepping forward to put his talents into our nation” by leading DOGE.

Meanwhile, Mr Musk, who was wearing a DOGE-branded baseball cap and a T-shirt with “The Dogefather” written on it, said it was “not the end of DOGE, but the beginning” and that the DOGE team would “only grow stronger”.

The 53-year-old added that he would continue to visit the White House and would still be an adviser to Mr Trump.

Mr Musk wore a T-shirt with "The Dogefather" written on it. Pic: Reuters
Image:
Mr Musk wore a T-shirt with “The Dogefather” written on it. Pic: Reuters

During the press conference, Mr Trump also turned to various conflicts around the globe, telling reporters that Israel and Hamas are “very close to an agreement” for a ceasefire in Gaza.

The president said an agreement with Iran to stop it from developing nuclear weapons was also “very close”.

Meanwhile, following recent tensions between India and Pakistan, Mr Trump took credit for de-escalating the situation between the two countries.

Read more from Sky News:
How USAID cuts are affecting the world
‘Harvard isn’t Harvard anymore’

The US president had handed Mr Musk the task of cutting government spending by sacking federal workers and eliminating bureaucratic waste as head of the newly formed DOGE department.

Mr Musk oversaw drastic cuts to America’s humanitarian efforts, leading to criticism that the US was relinquishing some of its global influence.

Despite promising to save taxpayers as much as $2trn (£1.5trn), DOGE currently estimates its efforts have saved $175bn (£130bn).

Mr Musk claimed the savings could be even higher, saying in the Oval Office on Friday: “We do expect over time a trillion dollars in savings. Say by the middle of next year, with presidential support, we can do it.”

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The moment took place before his interview with Rob Schmitt in front of the Republican crowd.

Mr Trump read out a list of savings DOGE has allegedly made, including cutting $101m spent on DEI (diversity, equity and inclusion) policies in the Department of Education, $59m on hotel rooms for migrants in New York, $42m on a project for social and behavioural change in Uganda, £24m “for an Arab Sesame Street” and $8m “for making mice transgender”.

But questions have been raised about whether the department has actually saved taxpayers as much money as suggested.

Meanwhile, Mr Musk – who famously brought his son X Æ A-12 to the Oval Office – has expressed frustration about resistance to his ideas, and clashed with other senior members of the Trump administration.

He claimed DOGE had been blamed for cuts that had nothing to do with his department.

U.S. President Donald Trump speaks as Elon Musk carries X Æ A-12 on his shoulders in the Oval Office of the White House in Washington, D.C., U.S., February 11, 2025.   REUTERS/Kevin Lamarque     TPX IMAGES OF THE DAY
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Elon Musk carries X Æ A-12 on his shoulders in the Oval Office. File pic: Reuters

“What we found was happening was if there were any cuts anywhere, people would assume that was done by DOGE,” he explained.

“We essentially became the ‘DOGE’ boogie man.”

It comes after Mr Musk’s father, Errol Musk, speaking to Gillian Joseph on The World earlier this week, insisted there had been “no rift between Elon and Donald Trump”.

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Errol Musk says his son isn’t a very good politician

As a “special government employee”, US law allowed Mr Musk to serve for 130 days, which would have ended around Friday.

He announced he was leaving in a post on X, in which he said: “I would like to thank President Donald Trump for the opportunity to reduce wasteful spending.”

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Podcast: new Tesla Model S/X, robotaxi service is coming, new EV price war, and more

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Podcast: new Tesla Model S/X, robotaxi service is coming, new EV price war, and more

In the Electrek Podcast, we discuss the most popular news in the world of sustainable transport and energy. In this week’s episode, we discuss the new Tesla Model S/X “refresh”, robotaxi service is coming, a new EV price war in China, and more.

The show is live every Friday at 4 p.m. ET on Electrek’s YouTube channel.

As a reminder, we’ll have an accompanying post, like this one, on the site with an embedded link to the live stream. Head to the YouTube channel to get your questions and comments in.

After the show ends at around 5 p.m. ET, the video will be archived on YouTube and the audio on all your favorite podcast apps:

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We now have a Patreon if you want to help us avoid more ads and invest more in our content. We have some awesome gifts for our Patreons and more coming.

Here are a few of the articles that we will discuss during the podcast:

Here’s the live stream for today’s episode starting at 4:00 p.m. ET (or the video after 5 p.m. ET:

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Environment

Kia hits a milestone as the EV5 launches in Singapore

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Kia hits a milestone as the EV5 launches in Singapore

Kia’s electric SUV has already become a hit in several overseas markets. The EV5 is now arriving as the first electric Kia to be assembled in Singapore, as it rolls out to new global markets.

Kia EV5 arrives as its first locally made EV in Singapore

Shortly after its introduction at the 2023 Chengdu Motor Show, Kia launched the EV5 in China, with prices starting at about 20,000 (149,800 yuan).

Kia is now seeing a full-on recovery in China, largely thanks to the new electric SUV. Its joint venture partner in China, Yueda Kia, ranked first in sales growth among JV brands.

In China, Kia sold over 248,000 vehicles last year, the first time it has crossed the 200,000 mark since 2020. The EV5 is made at Yueda Kia’s manufacturing plant in China and exported to overseas markets like Australia and Thailand.

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In fact, the EV5 is currently the fourth best-selling EV in Australia this year through April, ahead of every BYD vehicle.

The EV5 is slightly smaller than the Tesla Model Y at 4,615 mm in length, 1,875 mm in width, and 1,715 mm in height.

Kia-EV5-singapore
Kia EV5 (Source: Kia Singapore)

After launching the EV5 in Singapore on May 28, Kia hit a milestone. The electric SUV arrives as Kia’s first locally assembled EV in the region.

The EV5 was officially launched during an event at Hyundai Motor Innovation Groupe Centre Singapore, where it will be made. It will join other Hyundai Motor electric cars, including the IONIQ 5 and IONIQ 6. Hyundai also builds the IONIQ 5 robotaxi here and exports it to the US.

Kia-EV5-Singapore
Kia EV5 (Source: Kia)

Kia’s distributor, Cycle and Carriage, will sell the EV5 in three variants: Air, Earth, and a sporty GT-line. Two battery sizes will be available, 64.2 kWh and 88.1 kWh, providing range of 400 km and 540 km, respectively.

Prices for the base Air trim start at $194,000 (SDG), including COE. The Earth and GT-Line models start at $210,500 (SDG) and $260,000 (SDG) with COE.

Kia-EV5-interior
Kia EV5 interior (Source: Kia)

Later this year, Kia will launch the global version of the EV5, which will be made at its Autoland Gwangju manufacturing plant in South Korea. It will be sold in overseas markets, including Europe and Canada, but not the US.

Kia confirmed the EV5 will be “exclusively for the Canadian market” in North America. It will be available in FWD and AWD powertrains. Two battery sizes will be offered: 60.3 kWh or 81.4 kWh, providing a range of up to 500 km (310 miles).

Source: Cycle & Carriage Kia Pte Ltd, The Straits Times

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