science

HL23V

HL23V is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand HL23V rather than just read about it. In short: HL23V was reputedly a type C RNA tumor virus first isolated in 1975 from cultured human acute myelogenous leukaemia peripheral blood leukocytes in the laboratory of Robert Gallo, which would have been the first cancer-causing retrovirus isolated from human sera. It was later shown to be a laboratory contaminant of three monkey viruses.

Key takeaways

HL23V belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect HL23V to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HL23V from memory before moving on to harder problems.

Reference excerpt

HL23V was reputedly a type C RNA tumor virus first isolated in 1975 from cultured human acute myelogenous leukaemia peripheral blood leukocytes in the laboratory of Robert Gallo, which would have been the first cancer-causing retrovirus isolated from human sera. It was later shown to be a laboratory contaminant of three monkey viruses. The journal Nature, which had published the original research, later retracted the article. Investigative journalist John Crewdson, writing in 2003, described how Gallo pretended mysterious laboratory accidents such as the unplugging of a laboratory freezer to excuse his failure to share samples of "HL23V" to researchers. As "HL23V" would have been the first human retrovirus discovered, bringing attention to Gallo and thus scientific prizes, observers noted that "23" was the number of Robert Gallo's birthday. Later in 1986, Max Essex of Harvard would announce the "discovery" of "HTLV-IV" in Senegalese women, supposedly a type C relative of HIV (then called HTLV-III) thought to be HIV-2. This similarly was determined to be a contaminant.

See also Simian sarcoma associated virus (SSAV or SSAV-1), one of two associated viruses comprising HL23V HTLV-1, the actual first human pathogenic retrovirus discovered in 1981

References

Further reading Science Fictions: A Scientific Mystery, a Massive Cover-up, and the Dark Legacy of Robert Gallo ISBN 0316090042, 2002, John Crewdson

Worked examples

Example 1 — a first encounter with HL23V

Start with the simplest possible case. Write down what HL23V claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to HL23V before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about HL23V ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of HL23V

In research: HL23V appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses HL23V in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: HL23V is common in secondary-school and first-year university syllabi. It links to neighbouring topics Controversial taxa, Medical error, RNA viruses, so understanding it makes those chapters shorter.
In everyday life: Look for HL23V outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study HL23V in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HL23V means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain HL23V out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HL23V in simple terms?

Why does HL23V matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study HL23V?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on HL23V.