Viral Diseases and Immunity

Azidothymidine (AZT) is the antiretroviral medication used for AIDS treatment. Retrovir is a brand name, and Azidothymidine Phosphate is not the standard drug name. Acyclovir treats herpes viruses, not HIV.

Howard Temin and David Baltimore independently discovered reverse transcriptase in 1970, an enzyme that transcribes RNA into DNA - a process crucial for HIV replication. Watson and Crick discovered DNA's double helix structure, while Wilkins and Franklin contributed to X-ray crystallography studies of DNA.

Polymorphic, companion, and FAT viruses are all recognized types of computer viruses. 'Memory virus' is not a standard classification in virology or computer science. While viruses do reside in memory, this is not considered a distinct virus category.

Worms (A) and Direct Action Viruses (C) both possess self-replication capabilities. Worms replicate independently across networks, while Direct Action Viruses replicate when specific files are executed. Trojan Horses (B) cannot self-replicate as they disguise themselves as legitimate software, and Polymorphic Viruses (D), while capable of replication, are not primarily defined by this property.

RNA viruses are unique because they use RNA instead of DNA as their genetic material. This allows for faster mutation rates since RNA viruses lack the proofreading mechanisms that DNA-based organisms have, making them evolve more quickly.

The A1C test (glycated hemoglobin) measures average blood sugar levels over the past 2-3 months by determining the percentage of hemoglobin coated with sugar. It's used to diagnose and monitor diabetes. It does not test for HIV, blood group, or dengue fever.

HIV primarily infects CD4 positive T-lymphocytes (helper T cells), which are crucial for immune system function. It can also infect macrophages and dendritic cells. HIV does not infect CD4 negative cells. Therefore option D (Both A and B) is correct because it includes both CD4 positive T-cells and macrophages.

All listed measures are valid HIV prevention strategies. Faithfulness to one partner reduces exposure risk, protected sex with condoms prevents fluid exchange, screened blood transfusion avoids contaminated blood, and sterile needles prevent transmission. HIV prevention requires multiple simultaneous precautions as no single measure is sufficient.

Acute HIV Syndrome (also called acute retroviral syndrome or seroconversion illness) is the initial flu-like illness occurring 2-4 weeks after HIV infection. It represents the body's immune response to viral replication, not progression to AIDS (which takes years without treatment). This stage includes fever, rash, and swollen lymph nodes.