Thursday, July 18, 2024

How Many Strains Of Hiv Are There

Implications For Vaccine Development

How many viruses are there?

Ultimate control of the HIV-1 pandemic is dependent on the development of an effective, preventive vaccine . Among the many challenges to achieving this goal, one of the greatest is HIV-1 diversity reflected by the presence of HIV-1 subtypes, circulating recombinant forms, and continuous viral evolution within populations and individual hosts. Hosts infected with HIV-1 have cellular and humoral immune responses to their infecting strains, but there is evidence of mutational escape by viruses from responses by CD8+ cytotoxic T cells and neutralizing antibodies over time., Although cross-reactive responses to other viral subtypes have been shown,, the strength and breadth of these responses are typically limited. Several researchers have developed multisubtype consensus sequences or expression cassettes and have coadministered vaccines and selected cytokines in attempts to increase the breadth and strength of the cyto-toxic T-cell response., Critical to the development of a successful HIV-1 vaccine will be our ability to decipher the genetic diversity of the virus, elicit broadly neutralizing antibodies, and generate strong CD4+ and CD8+ T-cell responses.,

Can You Contract More Than One Strain

Its possible to contract more than one strain of HIV. This is called superinfection. When superinfection occurs, the new strain can either replace or coexist in the body along with the original strain.

The exact prevalence of HIV superinfection is unknown, and estimates can vary based on individual studies. Some data suggest that the incidence rate of superinfection can range between 0 and 7.7 percent per year.

Superinfection can impact HIV treatment. This is because the new virus may be resistant to the antiretroviral drugs that a person is currently taking.

According to the CDC , superinfections that are difficult to treat with antiretroviral drugs are rare. Additionally, continuing to take antiretroviral drugs as directed can help to prevent a superinfection from occurring.

Its also possible for a person to contract both HIV-1 and HIV-2. This dual infection has a prevalence of up to

Beta South African Variant

This variant, known as B.1.351 or Beta, emerged independently from the U.K. strain but shares some of its mutations, according to the CDC. Data indicates that it first emerged in South Africa in October 2020 and has since spread to other countries, including the U.S. In late January, CDC director Rochelle Walensky told TODAY that it had already reached the point of community spread. This variant could also make reinfection more likely a vaccine study in South Africa found 2% of people who’d already had a version of the coronavirus had been reinfected with a variant. It also has an estimated 50% increase transmission.

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Mutation Rate And Quasispecies

The replication cycle of HIV within the cytoplasm of a susceptible CD4 T lymphocyte, macrophage or dendritic cell starts after entry into the cell and cleavage of the core followed by synthesis of one new DNA strain. The reverse transcriptase synthesizes the first DNA strain using the viral RNA as a template. After RNA digestion by the RNase activity the RT synthesizes the second complementary strand. Finally, the double-stranded DNA molecule is released into the nucleus and integrated into the human host cell genome .

Hiv Strains And Types

How Many Strains Of Hiv Are There?  ucsf


  • There are two main types of HIV HIV-1 and HIV-2 .
  • Like many viruses, HIV has the ability to mutate and change over time – within the main types of HIV there are many genetically distinct subgroups.
  • Tests to diagnose HIV and monitor the level of virus in the body that are sensitive to the full range of subtypes do exist, but may not be readily available in all settings.

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What Are The Types Of Hiv/aids Medicines

There are several different types of HIV/AIDS medicines. Some work by blocking or changing enzymes that HIV needs to make copies of itself. This prevents HIV from copying itself, which reduces the amount of HIV in the body. Several medicines do this:

  • Nucleoside reverse transcriptase inhibitors block an enzyme called reverse transcriptase
  • Non-nucleoside reverse transcriptase inhibitors bind to and later change reverse transcriptase
  • Integrase inhibitors block an enzyme called integrase
  • Protease inhibitors block an enzyme called protease

Some HIV/AIDS medicines interfere with HIVs ability to infect CD4 immune system cells:

  • Fusion inhibitors block HIV from entering the cells
  • CCR5 antagonists and post-attachment inhibitors block different molecules on the CD4 cells. To infect a cell, HIV has to bind to two types of molecules on the cells surface. Blocking either of these molecules prevents HIV from entering the cells.
  • Attachment inhibitors bind to a specific protein on the outer surface of HIV. This prevents HIV from entering the cell.

In some cases, people take more than one medicine:

  • Pharmacokinetic enhancers boost the effectiveness of certain HIV/AIDS medicines. A pharmacokinetic enhancer slows the breakdown of the other medicine. This allows that medicine to stay in the body longer at a higher concentration.
  • Multidrug combinations include a combination of two or more different HIV/AIDS medicines

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Hiv Transmission Risk For Several Sexual Activities



Dry kissing

Using unshared inserted sexual devices

Genital stimulation by a partner but no contact with semen or vaginal fluids

Bathing or showering together

Contact with feces or urine if skin is intact


Wet kissing

Fellatio without ejaculation or if a condom is used

Cunnilingus if a barrier is used

Oral-anal contact

Digital vaginal or anal penetration, with or without a glove

Use of shared but disinfected inserted sexual devices

Fellatio without a condom and with ejaculation

Cunnilingus if no barrier is used

Vaginal or anal intercourse if a condom is used correctly

Use of shared but not disinfected inserted sexual devices


Vaginal or anal intercourse with or without ejaculation if a condom is not used or is not used correctly

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The Animals In The Covid

The video claims that the animals involved in the Covid-19 vaccine studies had a 100% death rate. This may be true, but isnt likely to be due to effects of the vaccine.

We have written about this before. Chris Magee, head of policy and media at UK non-profit Understanding Animal Research , previously told Full Fact that in the case of Covid-19 vaccines, data already existed to indicate the vaccines were safe, which enabled researchers to run animal trials alongside the early stages of human trials.

Had the animals died during this process, he said, the human trials would have been immediately halted. The fact that they were not indicates the animals did not die unexpectedly.

He also told Full Fact that the animals used in drug trials are usually euthanized, so scientists can examine their internal organs for signs of pathology.

In addition, a Pfizer spokesperson has previously denied these claims to Reuters. They highlighted a September 2020press release about the effects oftheirmRNA vaccine in mice and non-human primates and a on its vaccine in primates.

AstraZeneca has published similar papers regarding its research in mice and non-human primates. Moderna hasalso released information about its animal trials.

None of these publications describe concerns arising from the results of the animal studies.

Coreceptor Use By Hiv

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Differential characteristics of viral subtypes and their interactions with the human host may influence HIV transmission and disease progression. The HIV strains capable of using the chemokine coreceptor CCR5 are more frequently transmitted than strains that use the CXCR4 co-receptor X4 viruses emerge later in infected patients and are associated with more rapid disease progression. All HIV-1 subtypes can use both coreceptors, but subtype D may be dualtropic most frequently. The percentage of X4 virus appears to be lower in subtype C than in subtype B, even when the viruses are obtained from patients with advanced AIDS.

Another important question is whether subtype differences result in variable rates of disease progression. There have been several prospective, observational studies of the course of HIV-related disease in cohorts infected with various subtypes. An early study was published in 1999 by Kanki et al., who had examined subtypes in 54 female sex workers in Senegal who were infected with HIV-1. Subtypes A, C, D, and G were represented, and the likelihood of AIDS developing was increased by a factor of eight among women infected with a non-A subtype as compared with those infected with subtype A. The subtypes were determined on the basis of the standard at the time, envelope-gene subtyping only thus, further genetic complexity may have been present.

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The 8 Week Interval Between Vaccines Is Not To Hit The Immune System While It’s Down

The Instagram video claims that it takes eight weeks for the body to produce new white blood cells. It says that the interval between the first and second dose of vaccine is therefore designed to hit the immune system while its down, as it claims that the first vaccine decreases the bodys ability to produce white blood cells by 50%. There is no evidence to support this.

White blood cells help the body defend against infection and disease. These blood cells have a range of different life spans, from hours to years, and white blood cell production is a continuous process. NHS Blood & Transplant says that when you donate blood, and therefore lose white blood cells, your body stimulates their production and levels return to normal within a few days.

It is true that the Joint Committee on Vaccination and immunisation is currently recommending a minimum interval of eight weeks between the first and second doses of the available Covid-19 vaccines.

The Green Book, which provides health professionals with the latest information on vaccinations, states that the consistent interval should be used for all vaccines to avoid confusion and simplify booking.

In addition, it says, this interval will help to ensure a good balance between achieving rapid and long-lasting protection. It references studieswhichhave shown better immune responses with longer intervals between vaccine doses.

What Is A Covid

Viruses are always changing, and that can cause a new variant, or strain, of a virus to form. A variant usually doesn’t affect how the virus works. But sometimes they make it act in different ways.

Scientists around the world are tracking changes in the virus that causes COVID-19. Their research is helping experts understand whether certain COVID-19 variants spread faster than others, how they might affect your health, and how effective different vaccines might be against them.

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What Is An Undetectable Viral Load

The aim of HIV treatment is to make you undetectable. This means that your viral load is so low that it cant be detected by the tests used to measure it.

Different laboratories may have different cut off points when classifying an undetectable viral load. However, most clinics in the UK classify undetectable as being below 20 copies/ml.

When youre on effective treatment and have an undetectable viral load, you cannot pass on the virus and HIV is not able to damage your immune system.

A large study called PARTNER looked at 888 gay and straight couples where one partner was HIV positive and one was HIV negative. Results found that where the HIV positive partner was on treatment and had an undetectable viral load, there were no cases of HIV transmission whether they had anal or vaginal sex without a condom.

A follow-up study PARTNER 2 also reported zero transmissions after almost 800 gay couples had sex more than 77,000 without condoms.

What Is The Omicron Variant

How Many Strains Of Hiv Are There?  ucsf

The new variant was first detected in specimens collected on November 11, 2021 in Botswana. Experts in South Africa first reported the Omicron variant to the World Health Organization on Nov. 24, 2021. They discovered the variant after COVID-19 infections suddenly began to go up.

The WHO grouped Omicron as a Variant of Concern. This category means the variant might have a higher transmissibility, cause more intense disease, and may be less likely to respond to vaccines or treatments. But researchers need more information to confirm these factors.

Early evidence suggests that the Omicron variant causes a higher risk of reinfection compared to other variants.

Current PCR tests for COVID-19 can effectively find Omicron cases. Experts found that one specific PCR test doesn’t identify one of the three target genes in people infected with Omicron. Because of this, these tests can specifically mark positive Omicron cases and, because of that, can detect this variant faster than with previous surges.

According to research, breakthrough infections are possible with the Omicron variant even if youre fully vaccinated. However, COVID-19 vaccines and boosters are still effective at preventing severe illness, hospitalizations, and death.

The Omicron variant is now the dominant strain in the U.S.

Experts are keeping a close eye on how the variant spreads or develops.

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Recombinant Strains Of Hiv Are Spreading Rapidly Around The World

Although it has so far only been seen in West Africa, other studies have shown recombinants are spreading more rapidly around the world.

Parts of the world, such as the US and Europe where there are high levels of immigration, are seeing increasingly mixed and complex variants of HIV. This is quite different to the early years of the HIV epidemic, when there were few dominant strains and no recombinants.

The researchers suggest we need to be wary of the rise in recombinants, as senior author Patrik Medstrand, professor of Clinical Virology at Lund University, explains:

HIV is an extremely dynamic and variable virus. New subtypes and recombinant forms of HIV-1 have been introduced to our part of the world, and it is highly likely that there are a large number of circulating recombinants of which we know little or nothing. We therefore need to be aware of how the HIV-1 epidemic changes over time.

The researchers drew their conclusions after looking at data gleaned in a Lund University project that carried out a long-term follow-up of HIV-infected people in Guinea-Bissau.

The team is now planning to spend more time looking at recombinant viruses and their occurrence among HIV-infected people in Europe.

In 2012, scientists at the University of California, Los Angeles , reported finding a clue as to why some people infected with HIV appear to remain healthy for 20 years or more, while others progress to AIDS much faster.

Classification And Molecular Epidemiology Of Hiv

Group M is the predominant circulating HIV-1 group. It has been divided into subtypes, denoted with letters, and sub-subtypes, denoted with numerals. Subtypes A1, A2, A3, A4, B, C, D, F1, F2, G, H, J, and K are currently recognized. HIV-1 subtypes, also called clades, are phylogenetically linked strains of HIV-1 that are approximately the same genetic distance from one another in some cases, subtypes are also linked geographically or epidemiologically. Genetic variation within a subtype can be 15 to 20%, whereas variation between subtypes is usually 25 to 35%. Over the past decade, advances in full-genome sequencing of HIV have led to the identification of circulating and unique recombinant forms . These are the result of recombination between subtypes within a dually infected person, from whom the recombinant forms are then passed to other people. The recombinant progeny are classified as circulating recombinant forms if they are identified in three or more people with no direct epidemiologic linkage otherwise they are described as unique recombinant forms .

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Delta Variant From India

This variant is believed to have first emerged in India in October 2020. It’s since spread to the U.S. and currently accounts for more than 6% of sequenced cases in the U.S., Dr. Anthony Fauci said at a recent news briefing. It also has increased transmissibility compared to other variants, according to the World Health Organization.

There Are Not 81 Strands Of Foreign Bacteria In The First Booster And There Are Not Eight Strands Of Hiv In The Second Vaccine Booster

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The Instagram video says that there are 81 strands of foreign bacteria in the first booster, and eight strands of HIV in the second booster vaccine. This is not true.

It is not clear where the claims originate from. In , there was a news story about a cancelled Covid-19 vaccine trial in Australia. The trial vaccine contained a small component derived from HIV. This was not able to cause HIV infection, but did cause an antibody response meaning that some trial participants had false positive HIV test results. This vaccine trial was terminated, and is not in use at all in the UK.

The JCVI has advised a preference for the Pfizer-BioNTech vaccine for the booster programme, regardless of which vaccine somebody initially had.

It has said that, alternatively, a half dose of the Moderna vaccine may be offered, or where mRNA vaccines cannot be offered, the AstraZeneca vaccine may be considered for those who received it previously.

The Pfizer vaccine and Moderna vaccines do not contain bacteria, or viral particles. They do not contain HIV.

The AstraZeneca vaccine does not contain bacteria. It does use a weakened version of a common cold virus from chimpanzees which has been modified so that it cannot replicate or cause disease. It is an entirely different virus to the HIV virus.

Dr Stephen Griffin, virologist and associate professor at Leeds Institute of Medical Research told us there is no HIV present in the vaccines.

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