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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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Politics

‘Shameful’ that black boys in London more likely to die than white boys, says Met Police chief

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'Shameful' that black boys in London more likely to die than white boys, says Met Police chief

It is “shameful” that black boys growing up in London are “far more likely” to die than white boys, Metropolitan Police chief Sir Mark Rowley has told Sky News.

The commissioner told Sunday Morning with Trevor Phillips that relations with minority communities “is difficult for us”.

Sir Mark, who came out of retirement to become head of the UK’s largest police force in 2022, said: “We can’t pretend otherwise that we’ve got a history between policing and black communities where policing has got a lot wrong.

“And we get a lot more right today, but we do still make mistakes. That’s not in doubt. I’m being as relentless in that as it can be.”

He said the “vast majority” of the force are “good people”.

However, he added: “But that legacy, combined with the tragedy that some of this crime falls most heavily in black communities, that creates a real problem because the legacy creates concern.”

Sir Mark, who also leads the UK’s counter-terrorism policing, said it is “not right” that black boys growing up in London “are far more likely to be dead by the time they’re 18” than white boys.

“That’s, I think, shameful for the city,” he admitted.

The Met Police chief’s admission comes two years after an official report found the force is institutionally racist, misogynistic and homophobic.

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Police chase suspected phone thief

Baroness Casey was commissioned in 2021 to look into the Met Police after serving police officer Wayne Couzens abducted, raped and murdered Sarah Everard.

She pinned the primary blame for the Met’s culture on its past leadership and found that stop and search and the use of force against black people was excessive.

At the time, Sir Mark, who had been commissioner for six months when the report was published, said he would not use the labels of institutionally racist, institutionally misogynistic and institutionally homophobic, which Casey insisted the Met deserved.

However, London Mayor Sadiq Khan, who helped hire Sir Mark – and could fire him – made it clear the commissioner agreed with Baroness Casey’s verdict.

After the report was released, Sir Mark said “institutional” was political language so he was not going to use it, but he accepted “we have racists, misogynists…systematic failings, management failings, cultural failings”.

A few months after the report, Sir Mark launched a two-year £366m plan to overhaul the Met, including increased emphasis on neighbourhood policing to rebuild public trust and plans to recruit 500 more community support officers and an extra 565 people to work with teams investigating domestic violence, sexual offences and child sexual abuse and exploitation.

Watch the full interview on Sunday Morning with Trevor Phillips from 8.30am on Sunday.

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Backlash as Air India crash report points to possible human error – here’s what experts think

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Backlash as Air India crash report points to possible human error - here's what experts think

As investigators continue to piece together the full picture, early findings of the Air India crash are pointing towards a critical area of concern — the aircraft’s fuel control switches.

The flight, bound for London Gatwick, crashed just moments after taking off from Ahmedabad airport on 12 June, killing all but one of the 242 people on board the plane and at least 19 on the ground.

According to the preliminary report by India’s Aircraft Accident Investigation Bureau (AAIB), the two engine fuel control switches on the plane were moved from the “RUN” to “CUTOFF” position.

These switches control fuel flow to the engines and should only be used when the aircraft is on ground, first to start the engines before a flight and later to shut them down at the gate.

They are designed so they’re unlikely to be changed accidentally, pointing to possible human error on the Air India flight.

The findings include the final conversation between the pilots and show there was confusion in the cockpit as well.

When one pilot asked the other why he cut off the fuel, he responded to say he did not do so.

Pic: Takagi
Image:
The Air India plane before the crash. Pic: Takagi

Moments later, a Mayday call was made from the cockpit, but the plane could not regain power quickly enough and plummeted to the ground.

Captain Amit Singh, founder of Safety Matters Foundation, an organisation dedicated to aviation safety, told Sky News: “This exchange indicates that the engine shutdowns were uncommanded.

“However, the report does not identify the cause – whether it was crew error, mechanical malfunction, or electronic failure.”

Previous warning of ‘possible fuel switch issue’

“The Boeing 787 uses spring-loaded locking mechanisms on its fuel control switches to prevent accidental movement,” Mr Singh explained.

But a previous bulletin from the Federal Aviation Administration (FAA) “warned that these switches might be installed with the locking feature disengaged,” he said.

This could “make them susceptible to unintended movement due to vibration, contact, or quadrant flex”, he added.

A tail of an Air India Boeing 787 Dreamliner plane that crashed is seen stuck on a building. Pic: Reuters
Image:
The plane’s tail lodged in a building. Pic: Reuters

Speaking to Sky News, aviation expert Terry Tozner said: “The take-off was normal, the aircraft rotated at the correct speed left the ground and almost immediately, the cut-off switches were selected to off, one then two.

“But nobody has said with any clarity whether or not the latch mechanisms worked okay on this particular aircraft. So we can only assume that they were in normal working order.”

In India, there has been a backlash over the findings, with some saying the report points to pilot error without much information and almost dismisses the possibility of a mechanical or electric failure.

Indian government responds

India’s civil aviation minister Kinjarapu Ram Mohan Naidu has been quick to respond, saying: “We care for the welfare and the wellbeing of pilots so let’s not jump to any conclusions at this stage, let us wait for the final report.

“I believe we have the most wonderful workforce of pilots and crew in the whole world.”

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India plane crash survivor carries brother’s coffin

Both pilots were experienced, with around 19,000 flying hours between them, including more than 9,000 on Boeing 787s.

The report says the aircraft maintenance checks were on schedule and that there are no signs of fuel contamination or a bird strike.

So far, no safety recommendations have been issued to Boeing or General Electric, the engine manufacturers.

Concern over destroyed flight recorder

Mr Singh said “the survivability of the flight recorders also raises concern”.

The plane’s rear flight recorder, designed to withstand impact forces of 3,400 Gs and temperatures of 1,100C for 60 minutes, “was damaged beyond recovery”.

Read more:
Everything you need to know about the crash
Air India’s lone survivor is nothing short of miracle

“The Ram Air Turbine (RAT), which deploys automatically when both engines fail and power drops below a threshold, was observed as deployed in CCTV footage when the aircraft was approximately 60ft above ground level,” Mr Singh said.

“This suggests that the dual engine failure likely occurred before the official timestamp of 08:08:42 UTC, implying a possible discrepancy.”

Prime Minister Narendra Modi/X/AP
Image:
India’s Prime Minister Narendra Modi visiting the crash site. Pic: X/AP

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Mr Singh said it was also “of particular note” that the plane’s emergency locator transmitter (ELT) did not send any signal after the crash.

“Was the ELT damaged, unarmed, mis-wired, or malfunctioning?” he said.

The report has generated more questions than answers on topics including human error, power source failures and mechanical or electrical malfunction.

The final report is expected to take a year. Meanwhile, families grapple with the unimaginable loss of loved ones in one of the worst disasters in India’s aviation history.

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Environment

Tesla launches new software update with Grok, but it doesnt even interface with the car

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Tesla launches new software update with Grok, but it doesnt even interface with the car

Tesla has launched a new software update for its vehicles that includes the anticipated integration of Grok, but it doesnt even interface with the car yet.

Earlier this week, CEO Elon Musk said that Tesla would integrate Grok, the large language model developed by his private company, xAI, into its vehicles.

Today, Tesla started pushing the update to the fleet, but there’s a significant caveat.

The automaker wrote in the release notes (2025.26):

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Grok (Beta) (US, AMD)

Grok now available directly in your Tesla

Requires Premium Connectivity or a WiFi connection

Grok is currently in Beta & does not issue commands to your car – existing voice commands remain unchanged.

First off, it is only available in vehicles in the US equipped with the AMD infotainment computer, which means cars produced since mid-2021.

But more importantly, Tesla says that it doesn’t send commands to the car under the current version. Therefore, it is simply like having Grok on your phone, but on the onboard computer instead.

Tesla showed an example:

There are a few other features in the 2025.26 software update, but they are not major.

For Tesla vehicles equipped with ambient lighting strips inside the car, the light strip can now sync to music:

Accent lights now respond to music & you can also choose to match the lights to the album’s color for a more immersive effect

Toybox > Light Sync

Here’s the new setting:

The audio setting can now be saved under multiple presets to match listening preferences for different people or circumstances:

The software update also includes the capacity to zoom or adjust the playback speed of the Dashcam Viewer.

Cybertruck also gets the updated Dashcam Viewer app with a grid view for easier access and review of recordings:

Tesla also updated the charging info in its navigation system to be able to search which locations require valet service or pay-to-park access.

Upon arrival, drivers will receive a notification with access codes, parking restrictions, level or floor information, and restroom availability:

Finally, there’s a new onboarding guide directly on the center display to help people who are experiencing a Tesla vehicle for the first time.

Electrek’s Take

Tesla is really playing catch-up here. Right now, this update is essentially nothing. If you already have Grok, it’s no more different than having it on your phone or through the vehicle’s browser, since it has no capacity to interact with any function inside the vehicle.

Most other automakers are integrating LLMs inside vehicles with the capacity to interact with the vehicle. In China, this is becoming standard even in entry-level cars.

In the Xiaomi YU7, the vehicle’s AI can not only interact with the car, but it also sees what the car sees through its camera, and it can tell you about what it sees:

Tesla is clearly far behind on that front as many automakers are integrating with other LLMs like ChatGPT and in-house LLMs, like Xiaomi’s.

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