HIV resistant

Any infection at different people proceeds differently. The course of a disease in a particular person is determined by a number of factors: the general condition of the body and previous diseases, the type of microorganism that entered the body, the characteristics of the patient's genotype, the presence of concomitant infections, etc. For most diseases, the statistics of typical symptoms and the timing of their course does not include cases when the disease has passed "mildly" or is generally asymptomatic. And although such situations usually fall out of the medical field, they are of particular interest, because they can point to unknown mechanisms of protection against infections. In this sense, the infamous AIDS, which today is considered an incurable disease, is no exception.

Almost from the very beginning of the HIV epidemic, rare cases have been noted when a person turned out to be completely resistant to the virus or the carriage of the virus did not pass into the stage of AIDS. Studies have shown that the surface lymphocytic protein CCR5 is “to blame” for this, or rather, its absence in some people.

The fact is that when the HIV virus enters the body, it seeks to penetrate into lymphocytes - the most important immune blood cells involved in protecting the body from infections. To be able to enter a lymphocyte, the envelope protein on the surface of the virus must bind to two cellular protein receptors on the surface of lymphocytes, one of which is the CCR5 protein (Deng et al., 1996). It turned out that some people are carriers of a mutation that prevents the synthesis of CCR5 and, accordingly, their lymphocytes are resistant to infection by most HIV variants.

There may be other mechanisms of resistance to HIV that we simply do not know about. For example, a team of French scientists working with a group of 1700 HIV-infected people recently published the results of a study of two unusual cases of resistance to infection that were not associated with the absence of the CCR5 protein (Colson et al., 2014). In the first case, the patient was diagnosed as early as 1985, but although he did not take any antiviral drugs, standard tests indicated complete elimination of the virus. Neither in the blood nor in the blood cell culture of this person were traces of the presence of a "live" virus.

Of course, the first question that arose was – was the patient really infected, or did the researchers encounter a rare diagnostic error? However, additional tests showed that the fact of infection had taken place: antibodies to HIV and individual fragments of viral proteins were found in his blood, as well as negligible amounts of viral DNA, which could only be determined using highly sensitive methods.

The researchers tried to infect lymphocytes taken from this patient with a "laboratory" variant of HIV. However, this attempt failed, unlike control lymphocytes taken from other patients. This time, the researchers accurately established that the CCR5 protein is present on the lymphocytes of an unusual patient, and realized that they are dealing with a new mechanism for blocking the replication of the HIV genome.

* Codon - a unit of the genetic code, which is a triple of nucleotide residues in DNA or RNA that codes for one amino acid

A possible clue to the explanation of this phenomenon was found in the small amounts of viral DNA that were still able to be isolated from the patient's blood. An analysis of their nucleotide sequence showed that this viral genome is simply crammed with mutations. About a quarter of the codons * encoding the amino acid tryptophan turned out to be mutated, which as a result turned into stop codons that stop protein synthesis.

In fact, the immune defense mechanisms that could inactivate the virus in this way are already known. HIV refers to viruses with an RNA genome, and in order to multiply, it must go through the reverse transcription stage, i.e. RNA must turn into DNA. A group of cellular proteins from the APOBEC3G family can “intercept” the viral genome at this stage. They “tear off” the amino group (–NH 2) from cytosine nucleotides, turning them into uracil ones. As a result, instead of complementary pairs of nucleotides "cytosine-guanine", pairs "uracil-adenine" appear in the genome. And since two guanines enter the tryptophan codon, replacing them with adenine turns the tryptophan codon into a stop codon (Sheehy et al., 2002).

Usually HIV manages to bypass this level of protection: it has a special protein that attacks and destroys APOBEC3G. But for some reason this did not happen this time, and the entire viable virus was mutated to a state of complete loss of functionality.

Assuming that this case may not be isolated, the researchers began to search among their 1500 patients with a similar history. And found! This person also failed to detect DNA or RNA viruses using standard methods. The tiny fragments of viral DNA that were found in his blood also contained a large number of mutations similar to those found in the first case. However, the lymphocytes of the second patient turned out to be unstable to infection with the “laboratory” version of HIV, so it is possible that he has a different mechanism of resistance to the virus.

A promising direction of this work is the further study of the mechanisms of resistance of lymphocytes of the first patient in experiments on infection with a "laboratory" strain of the virus. This person is thought to have a rare variant of the APOBEC3G gene that HIV cannot bypass. But although this would be an interesting find, such a discovery, most likely, will not be widely practical application, since only its carriers can benefit from such a mutation. However, the hope remains that the study will uncover some hitherto unknown immune defense mechanisms, which will give impetus to the development of new drugs or methods to prevent HIV infection.

The authors of this work also put forward a hypothesis that virus "fragments" in the form of short proteins, formed as a result of early stoppage, may play a role in protecting cells from re-infection with HIV. protein synthesis on new stop codons. These proteins can perform a protective function either, for example, by competing with some proteins necessary for the virus, or by stimulating the immune system in some special way. It has even been suggested that the observed phenomenon of the formation of viral resistance is a natural process of HIV endogenization, i.e., an evolutionary process, as a result of which the viral nucleic acid becomes part of the genome of another species (in this case, a human).

This assumption is not so fantastic: our genomes are full of "traces" of ancient infections - infections with retroviruses that can integrate their hereditary material into our DNA. After all, if not a pathogenic, but an inactivated virus is inserted into the carrier's genome, which also provides protection against re-infection, then it has a much greater chance of spreading in the population. And if we start a large-scale search for people who carry a virus with a large number of inactivating mutations, then we will have a chance to observe HIV endogenization in real time.

Literature.
Colson P., Ravaux I., Tamalet C., et al. HIV infection enroute to endogenization: two cases. // Clin. Microbiol Infect. 2014. V. 20. N. 12. P. 1280-1288.
Sheehy A. M, Gaddis N. C., Choi J. D., and Malim M. H. Isolation of a human gene that inhibits HIV-1 infection and is suppressed by the viral Vif protein. // Nature. 2002. V. 418. P. 646-650. DOI: 10.1038/nature00939.
Deng H., Liu R., Ellmeier W., et al. Identification of a major co-receptor for primary isolates of HIV-1. Nature. 1996. V. 381. P. 661-666.

Scientists from the Russian National Research Medical University named after N.I. Pirogov together with specialists from the Scientific Center named after N.I. Kulakova and Moscow State University have created human embryos with a genome that determines resistance to infection with the human immunodeficiency virus (HIV).

The results were achieved by editing the genome of embryos at the stage of one cell (zygote) using the CRISPR-Cas9 system. Zygotes were edited by cutting out 32 nucleotides from the CCR5 gene sequence, which encodes the receptor for which the virus attaches to blood cells.

Do some of the people on Earth naturally have this particular variant of the CCR5 gene? and they showed increased resistance to HIV infection. Such technology in the future may help protect children from HIV-infected mothers with a poor response to antiviral therapy from infection with the immunodeficiency virus.

The Pravda.Ru correspondent spoke about the successes of Russian scientists in the fight against HIV, as well as about the tasks of genetic engineering, with Denis Rebrikov, Doctor of Biological Sciences, Professor of the Russian Academy of Sciences, Vice-Rector for Research of the Russian National Research Medical University. N. I. Pirogova, Head of the Laboratory of Genome Editing, NMIC V. I. Kulakova.

— I would like to know the details on the issue of creating HIV-resistant human embryos?

- In general, work with systems for editing the genome of human embryos began not so long ago. The first attempt was made by Chinese researchers in 2015, three years ago. Their work made its way into publication with great difficulty, because scientific journals at that time, it was poorly understood whether it was possible to publish such data and how legally it was allowed to do such experiments. Changing the human genome at the level of the embryo is a new direction, and it is still poorly developed both in terms of legislation and at the level of public perception.

Our society is very conservative. Even GMOs, which have been used in agriculture for over 30 years, still cause controversy among people. Already two generations grew up on GMOs. Numerous studies have proven that GMOs are safer for humans than "classical" agricultural technologies. And society is still wary of plants and animals created using genetic engineering methods.

But this is natural: people are always very suspicious of what they do not understand. For them, this is a black box, beautifully presented in theaters with blockbusters about mad scientists making mutants in their laboratories. Therefore, the entry of technologies for changing the genome of human embryos into medical practice will be difficult, primarily because of the perception of society.

Returning to the history of editing the genome of embryos, it should be clarified that, in fact, DNA modification is carried out not on the embryo as such, but on a single cell - the zygote, which is obtained as a result of fertilization: the fusion of the egg and sperm. The zygote is the first cell from which the human body develops. Accordingly, the most convenient moment when we can change the genetic program so that it is changed throughout the body is the zygote stage.

Interviewed by Lada Korotun

Prepared for publication by Svetlana Shirokova

The inhabitants of Russia are genetically resistant to AIDS - St. Petersburg geneticists came to such a paradoxical conclusion when they decided to figure out what prevents the immunodeficiency virus from scything down careless Russians with its deadly scythe, Novye Izvestia writes today. The Americans were the first to talk about the genetic predisposition of some people to AIDS at the beginning of the 21st century.

Scientists from the US National Cancer Center were interested in the question: why among drug addicts and other people at high risk of contracting AIDS are people who are constantly bypassed by HIV infection. It turned out that their genes stood guard over the health of specific people. Or rather, a single mutation of a gene called CKR-5.

According to the publication, the altered gene strengthens lymphocytes and, ultimately, makes the body relatively resistant to HIV infection, although the chance to get deadly virus still remains. In extremely rare cases, the same person may have two identical mutations of the mentioned CKR-5 gene, protecting against AIDS by 100%.

Immediately after the sensational discovery, scientists from other countries became interested in the CKR-5 gene mutation. It turned out that the percentage of owners of the altered gene depends on nationality. The Poles were the most immune to AIDS. In the course of research, it turned out that 26-27% of the inhabitants of Poland have a modified gene that protects against AIDS. In England, this figure was 22%. But as we moved to the East, the number of lucky ones rapidly decreased. So, only 2-3% of Turks are resistant to AIDS. In the genotype of the inhabitants of the Land of the Rising Sun, there is no saving mutation at all. Representatives of the Negroid race do not have it either, regardless of their country of origin.

In Russia, the study of the genotype of citizens was carried out by specialists from the laboratory of prenatal (prenatal) diagnostics of the Ott Research Institute of Obstetrics and Gynecology under the guidance of Corresponding Member of the Russian Academy of Medical Sciences Vladislav Baranov. A total of 700 people were examined, including Russians, Tatars, Uzbeks, Azerbaijanis, Kazakhs, Georgians.

The most resistant to AIDS infection were Russians and Tatars. Nature has awarded every fourth representative of these peoples with a mutated gene that provides relative resistance to HIV infection. But 1-1.5% of our fellow citizens have as many as two mutations of the CKR-5 gene, which completely protects them from HIV. The Uzbeks were a little less fortunate, only 15% of them have an altered gene. For Azerbaijanis and Kazakhs, the figure is even lower - 10%. And among the Georgians there was not a single lucky one, in this they are sadly similar to the Japanese and Africans. Based on materials from the site: inter.su

Researchers at the Stanford Institute have proven that not all people are susceptible to this virus. Let's see what the essence of the virus is and how it works inside the body.

The spread of HIV today is a global biological problem of mankind. Drug addiction, promiscuity, unsterile medical supplies, and sometimes an HIV-positive mother are the main routes of transmission from one person to another. People with HIV are considered to be the living dead, as the human immunodeficiency virus turns into acquired immunodeficiency syndrome, and then a person can die from a simple infection or wound, since his body is simply not able to fight anything.

The main task of medical scientists who deal with this particular disease is to find a way to treat HIV. The first step to finding this very method is the invention of drugs that, no matter how, support the life of patients. They do not cure, but only cause addiction, but still maintain the health of patients, which is just as important.
Researchers at the Stanford Institute have proven that not all people are susceptible to this virus. Let's see what the essence of the virus is and how it works inside the body. Having entered the body, the virus enters T-cells, which are the central regulators of the immune response (in fact, they ensure the body's fight against various infections), where the virus binds to the surface of the CCR5 and CXCR4 proteins. It turned out that people who have mutations in CCR5 are resistant to HIV. It turned out as follows. One person had two problems at once: HIV and leukemia. As you know, the treatment of leukemia requires a bone marrow transplant, which they did. this person. After the transplant, he got rid of both leukemia and HIV. Scientists, of course, began to understand why this happened. It turned out that the donor had mutations in the CCR5 protein, which were passed on to the person who received the bone marrow transplant.

Thus, knowing the possibilities of removing the virus from the body, it can be treated. The way to make the CCR5 protein "mutated" relies on a technique by California scientists. Their work is related specifically to the study of connections in CCR5, methods of penetration into it and breaking DNA fragments in the protein. The challenge for the Stanford scientists is to properly fold three genes into DNA in the CCR5 protein that confer resistance to HIV. Such a triplet provides the strongest protection of a person from HIV infection.
Clinical studies of this method of treatment will begin within 3-5 years. For people who are infected with HIV, it is not guaranteed that they will completely get rid of the virus, but they will be able to stop the complete immune inactivity of the body absolutely free of charge. Patients will be injected with mutated T cells.

Is HIV not as scary as it is painted?

I have two news for you: good and bad. I'll start with a good one. In September of this year, UNAIDS (UNAIDS - the UN organization that deals with the problem of HIV / AIDS on a global scale) published new statistics on HIV. Since 2001, the number of reported HIV infections worldwide has dropped by a third. The number of deaths from AIDS has also decreased. In 2001, 2.3 million people died from AIDS and related diseases. In 2012 - 1.6 million people.

As the report says, all this is due to the fact that antiretroviral therapy has become more accessible. More than half of officially registered HIV-infected people are being treated.

Back in 2008, epidemiologists exhaled and stated: our fears about the HIV pandemic are greatly exaggerated. Extinction of earthlings from AIDS and accompanying diseases is not expected. Except in Africa. And then, if we take the whole world, there are real chances to stop the infection.

Modern medicine claims that HIV can be safely transferred to the category of chronic diseases, with which - with adequate therapy - you can live a full life. With proper therapy and healthy way An HIV-infected person can live longer than an uninfected person. In medical terms, the right therapy will delay the development of immunodeficiency syndrome indefinitely. All in all, HIV is like diabetes, you can't cure it, but you can live.

In general, HIV is a slow killer and in most cases is in no hurry to bury its owner. The disease develops within 5-10 years. At the same time, the carrier of the virus does not experience any particular inconvenience, except for enlarged lymph nodes, which do not even hurt. The person may not be aware that they are infected. Obvious symptoms appear only on two final stages. Without any treatment, an HIV-infected person can live 10 years. Occasionally more.

The modern method of treating HIV has the complex name Highly Active Antiretroviral Therapy (HAART or VART). To suppress and reduce the content of the virus in the body, at least 3 drugs are used. When the concentration of the virus falls, the number of lymphocytes in the blood is restored. Almost normal immunity returns to the infected. With a minimum content of the virus in the blood, the risk of infecting a partner is greatly reduced and it becomes possible to conceive a healthy child.

There are people who are resistant to HIV infection. These lucky ones have a genetic mutation, which, as scientists suggest, appeared about two and a half thousand years ago. Strangely, only in Europe. Completely immune to HIV 1% of the European population, 10-15% of Europeans have partial resistance. Among those already infected, about 10% are non-progressors, i.e. They do not develop AIDS for a long time.
Elusive and relentless killer

And now the bad news. Die of AIDS. Guaranteed. No matter how well a person is treated, AIDS will sooner or later reap its harvest. For comparison: mortality from the most terrible disease of the past, "God's punishment", bubonic plague - 95%, from pulmonary - 98%. From AIDS - 100%. AIDS makes no exception.
Despite the fact that the HIV virus is one of the most studied pathogens of infectious diseases , there is no cure for HIV/AIDS. And probably never will. The difficulty is that the HIV virus has a high ability to mutate. In fact, there is not one, but four varieties of HIV viruses: HIV-1, HIV-2, HIV-3 and HIV-4. The most common, because of which, in fact, there was a danger of a pandemic, is HIV-1. It was first opened in 1983. HIV-2 hosts mainly in West Africa. The other two varieties are rare. There are dozens of recombinant variants of the virus. If you follow the news, you have probably heard or read about a new type of HIV-1 recently identified in Novosibirsk.

That's not all. Each variety also knows how to mutate and forms more and more new strains in the carrier's body. Eventually, a drug-resistant strain emerges. Doctors can't keep up with the fast virus. Developing new vaccines and testing them is a long, complicated, and expensive undertaking. That's why any therapy sooner or later becomes ineffective, and death awaits an HIV-infected person.

HAART only reduces the concentration of the virus in the body and keeps it at a minimum level. Physicians have not learned how to completely remove the virus from the body. The virus infects not only lymphocytes, but also other cells with a long lifespan. Such a reservoir for antiviral drugs is invulnerable. In these impregnable fortresses, HIV slumbers for years, waiting in the wings.

In addition, HAART drugs are extremely toxic. Side effects anti-HIV therapies may be as deadly as AIDS itself. Among them are liver necrosis, toxic epidermal necrolysis (Lyell's syndrome), lactic acidosis and other diseases with a high probability of death.
There are cases when people became infected with two different strains of the HIV virus. This is the so-called superinfection. Until now, the causes and methods of its occurrence have not been found. A double set of viruses is more resistant to drugs. Superinfected people die much faster.
HIV is not easy to diagnose. There are 3 methods for diagnosing HIV: PCR, ELISA and immunoblot. PCR analysis is the earliest diagnosis of HIV, it can be taken as early as 2-3 weeks after the alleged infection. However, PCR often deceives and gives a false negative result. For ELISA analysis, you will have to wait about a month. Here the situation is reversed by PCR: ELISA can be positive in people with tuberculosis, multiple blood transfusions, and oncology. The most accurate analysis is the immunoblot. For absolute certainty, you need to take an analysis once a year.

AIDS - a disease of decent people?

HIV arrived in the former USSR in 1986. As you know, there was no sex in the USSR, drug addiction and homosexuals, too, so they did not pay much attention to the virus. In general, against the background of the rest of the world (AIDS and concomitant diseases in Europe by that time had already become, as doctors cautiously put it, a significant cause of death among the population from 20 to 40 years old), the situation in the USSR was rosy. For the entire Union, there are less than a thousand detected cases.

And those are mostly students who got infected from Africans. The belief that HIV is a disease of drug addicts, homosexuals and prostitutes also played a big role. A decent person has nothing to fear. Some even perceived HIV as a new Stalin, who is carrying out a kind of purge of society from the marginalized. And then the USSR collapsed, along with it the epidemiological service. In 1993-95 HIV made itself known rather aggressively with outbreaks in Nikolaev and Odessa. Since then, it has not been possible to stop him.

Here is ITAR-TASS infographic for 2012:

A few more statistics, if you are not tired. According to 2013 data, 719,455 HIV-infected people were recorded in Russia. Over the past 5 years, their number has doubled. Statistics on HIV in Russia competes with those in Africa. And what is the saddest thing, successfully . The real number of infected people in Russia may be about a million people. And these are not gays, drug addicts or prostitutes (although they are still considered a high-risk group). Doctors say that HIV in Russia has a respectable face: the face of a socially secure, often family man, aged 20 to 40. Up to 45% of cases of infection are not due to infection through syringes or anal sex, but through heterosexual contacts. Because of the illusion of security, people are unwilling to be tested and treated. So it turns out that in the main risk group in modern Russia are those very decent people who believe that they have nothing to fear.

Doctors believe that the reason for this, frankly speaking, catastrophic situation is lack of a coherent AIDS program. Academician Pokrovsky is convinced that a systematic preventive campaign is needed among the population. First of all, Russians need to be convinced that HIV can catch up with everyone, regardless of the level of decency. Second, explain the need for protection and regular testing. Third, make prevention and testing easily accessible.

This year, 185 million rubles have been allocated from the budget for HIV prevention. True, the competition for holding an information campaign was announced on October 8. The results of the competition will be summed up on November 13. Prevention, therefore, will take a little over a month. And it should be held within a year, to be honest. So, most likely, the history of 2011 will repeat itself. Then the prophylaxis took 37 days. No testing or real help was provided. The money was spent on TV commercials and promotion of the Ministry of Health's HIV website. So much for fighting AIDS in Russian.

What do HIV and Elvis Presley have in common?

No, Elvis was not infected with HIV. But, like Presley, HIV has had a powerful impact on modern culture. Like Presley, HIV has become a source of various rumors, plausible and not very theories, conjectures and versions. This is typical for modern world, where there are a lot of people who want to earn / become famous and have access to the Internet. Or maybe they're just being honest?

There is a whole movement of HIV/AIDS denial, the so-called "AIDS dissidents". Among them are many famous scientists and even Nobel laureates. For example, Kary Mullis, who received the Nobel Prize for guess what? For the invention of the PCR method! If you remember, this is one of the methods for diagnosing HIV.

Wikipedia does not give an intelligible explanation for this amazing fact. But he only notes that Mullis is not a specialist in the field of virology. Or Heinz Ludwig Sanger, former, as Vicky, a professor of virology and microbiology, points out. Or Etienne de Harvin, again former pathology professor. Actively denies the viral nature of AIDS and former South African President Thabo Mbeki, successor to Nelson Mandela. According to the press, his anti-AIDS policy led to the death of 330,000 people.

Dissidents believe that HIV does not cause AIDS. AIDS is a non-communicable disease. Development over 5-10 years is an unusually long time for infection. The causes of AIDS are malnutrition, drugs, stress, anal sex, harsh living conditions, etc. That is why AIDS has chosen Africa, where 70% of the population lives below the poverty line. That is why, despite the supposedly terrible virus, the population of Africa during the official AIDS epidemic, contrary to all forecasts, doubled.

Moreover, dissidents argue that highly toxic HAART drugs may be the cause of AIDS symptoms. Kills what, by design, should save. Some believe that HIV/AIDS is like swine flu, a hoax. Pharmacists and government officials invented AIDS to make money selling expensive, very expensive drugs. Judge for yourself: the annual cost of therapy ranges from 10 to 15 thousand dollars. But these drugs must be taken for life.

In a word, HIV and the AIDS it causes are the perfect disease to make money. Otherwise, why are the companies that produce HAART drugs so eager to remain monopolists in the market? Why are HAART drugs still imported to Africa and India from developed countries, and not produced in Africa and India itself? After all, this would reduce the cost of treatment tenfold. And many more whys.

There are opinions that HIV / AIDS is an artificially derived virus. The latest bioweapon designed specifically to save white humanity from rampant blacks. As an argument, the story of the study of syphilis in Tuskegee (USA, Alabama) is cited. In 1932-1972. physicians observed the natural development of syphilis in African Americans.

The study participants (read: test subjects) did not receive any treatment. Despite the fact that in 1947 penicillin, an effective cure for syphilis, had already appeared. In the case of HIV, the experiment is already being set up on a planetary scale. It has been proven that blacks are more likely to get AIDS. In the United States, blacks make up almost half of AIDS patients - 43.1%. It is not typical for a virus to display such racial discrimination. And while Africa's population continues to grow, the AIDS epidemic could have far-reaching demographic consequences.

HIV is really purging Africa: a 15-year-old African has a 50/50 chance of dying from AIDS before they reach 30. True Russian roulette. HIV is systematically killing Africa's able-bodied population of reproductive age: those who can work and have children. Experts believe that the food crisis in southern Africa in 2002 and 2003 was not caused by drought. The real reason is weakening Agriculture. Workers are dying of AIDS.

Who will win: HIV or us?

Of course, compared to pneumonic plague or the Spanish flu, HIV is just a baby. Compare: in 1918-1919. 50-100 million people died from the Spanish flu. In just a year, the Spaniard killed about 5% of the world's population. Pneumonic plague was responsible for the first known pandemic. In 551-580. the so-called “Plague of Justinian” captured the entire civilized world of that time and claimed more than 100 million people with it. The “accomplishments” of HIV pale in comparison to these greedy and quick killers: in the 32 years since its discovery, HIV has killed “only” 25 million people. According to 2012 data, there are about 32 million HIV-infected people in the world. Even if you add up all the past and potential victims, HIV is barely half the Spanish woman's record.

However, both the Spaniard and the plague, having harvested, left the stage. HIV is in no hurry. For 32 years he has been in charge of the planet and is not going to leave. For 32 years, scientists have been struggling with a cure or vaccine and losing the competition with the virus. HIV is constantly mutating, changing masks, but its essence remains the same - a relentless killer.

The most terrible feature of HIV is that the virus is directly related to the basis of human existence: reproduction (except for the artificially created by man way of spreading the virus through syringes). The only absolutely reliable way to protect yourself from HIV infection is to refuse sex and childbearing. In other words, refuse to procreate.

Who will win in this terrible game “HIV vs humanity” is unknown. Do not forget that in addition to HIV, there are a couple of serious candidates for the killers of earthlings: nuclear weapons and environmental disaster. Perhaps the question is no longer whether our civilization will perish or survive, but what will destroy us first.