HTLV-I: The Forgotten Retrovirus

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Pneumocystis Carinii Pneumonia (PCP) cases reported

In June 1981, the U.S. Centers for Disease Control and Prevention (CDC) published a Morbidity and Mortality Weekly Report (MMWR) depicting five cases of a very rare lung infection, Pneumocystis carinii pneumonia (PCP), in young and previously healthy gay men living in Southern California. Besides PCP, these men had other unusual infections, which showed that their immune systems were also greatly compromised.  In fact, two of the men were dead by the time the report was published.

What was significant about this edition of the MMWR was that it marked the first official reporting of what became known as the AIDS epidemic. And closely linked with AIDS, of course, is the infamous retrovirus, HIV, which has been blamed for millions of deaths since then, and continues to take lives. The World Health Organization (WHO) reported that in 2017 alone over 900,000 people died from HIV-related illnesses.

HTLV-I: First, but forgotten

It is no wonder, then, that HIV took center stage among medical professionals, even though it was not the first dangerous human retrovirus uncovered.  The first, found in 1980, was Human T-cell Leukemia Virus-1, also now known as Human T-Cell Lymphotropic Virus or HTLV-I. This discovery caused a minor sensation at the time because, until then, it was believed that retroviruses (an RNA virus that transcribes its own genome into DNA and then integrates it into the host genome) existed only in animals. Now researchers knew that this potentially dangerous retrovirus had wormed its way into human beings as well.  However disturbing that discovery, just one year later it would be quickly eclipsed by an even more disturbing one: HIV.

The rest, as they say, is history.

Plea to irradicate HTLV-I

Today, even though HIV continues to be a serious problem, some voices are calling on the medical world to start dealing more pro-actively with HTLV-I, which they fear poses a powerful threat as well.  In an open letter to the WHO, some well-known virologists (including Robert Gallo, known for his pioneering work on HIV), warned that the time had come for the medical community to get serious in seeking to eradicate HTLV-I.  Though it has been 38 years since it’s discovery, there has not been an effective attempt to deal with it, even though it has been stated that “HTLV-I remains a strong threat to individual and community health, and even more so to global health because of the accelerated rate of human migration in recent times.”

So, what is HTLV-I anyway?

HTLV I TEM Image of Thin Section #2 HTLV I TEM Image of Thin Section #9 HTLV I TEM Image of Thin Section #12

Though most everyone has heard of HIV, few know about HTLV-I, despite its growing prevalence and potential danger.  The full name itself, Human T-cell Leukemia Virus-1, reveals something of what is involved here.  Leukemia?  Yes, but not just leukemia, either. HTLV-I is linked also to lymphoma and numerous other dangerous and crippling diseases, including a condition (known as HTLV-I associated myelopathy/tropical spastic paraparesis, or HAM/TSP) that causes symptoms similar to multiple sclerosis.

HTLV-I is clearly not a retrovirus that you want in your bloodstream.  Unfortunately, scientists estimate the number of infected people is upwards of five to ten million people. In southern Japan, for instance, about six percent of pregnant women are infected.  Numbers are also high, and getting higher, in the Caribbean, South America, Africa, and among some aboriginal communities in Australia.  Most people infected never show symptoms, making it easier to pass the retrovirus on (HTLV-I spreads like HIV, through blood, semen and breast milk). About three to five percent of those who have it will develop Adult T-Cell Leukemia, a cancer that generally kills people within a year of diagnosis.

Though great progress has been made in understanding and dealing with HIV, much more needs to be done with research on HTLV-I, the forgotten retrovirus.

Advanced Biotechnologies’ growth and purification of the HTLV-I virus in 1984 propelled the company into providing highly purified virus products to the global marketplace.

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1Open Letter to WHO from Gallo –
2MMWR Report from 1981 –
3WHO Global Health Observatory (GHO) data –
4The discovery of HTLV-1, the first pathogenic human retrovirus –