CD8+ cytotoxic T-lymphocytes (CTLs) perform a critical role in the immune control of viral infections, including those caused by human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV). As a result, genetic variation at CTL epitopes is strongly influenced by host-specific selection for either escape from the immune response, or reversion due to the replicative costs of escape mutations in the absence of CTL recognition. Under strong CTL-mediated selection, codon positions within epitopes may immediately “toggle” in response to each host, such that genetic variation in the circulating virus population is shaped by rapid adaptation to immune variation in the host population. However, this hypothesis neglects the substantial genetic variation that accumulates in virus populations within hosts. Here, we evaluate this quantity for a large number of HIV-1– (n ≥ 3,000) and HCV-infected patients (n ≥ 2,600) by screening bulk RT-PCR sequences for sequencing “mixtures” (i.e., ambiguous nucleotides), which act as site-specific markers of genetic variation within each host. We find that nonsynonymous mixtures are abundant and significantly associated with codon positions under host-specific CTL selection, which should deplete within-host variation by driving the fixation of the favored variant. Using a simple model, we demonstrate that this apparently contradictory outcome can be explained by the transmission of unfavorable variants to new hosts before they are removed by selection, which occurs more frequently when selection and transmission occur on similar time scales. Consequently, the circulating virus population is shaped by the transmission rate and the disparity in selection intensities for escape or reversion as much as it is shaped by the immune diversity of the host population, with potentially serious implications for vaccine design.

Microbiology is the study of microorganisms, which are unicellular or cell-cluster microscopic organisms. This includes eukaryotes such as fungi and protists, and prokaryotes, which are bacteria and archaea. Viruses, though not strictly classed as living organisms, are also studied. In short; microbiology refers to the study of life and organisms that are too small to be seen with the naked eye. Microbiology is a broad term which includes virology, mycology, parasitology, bacteriology and other branches. Microbiology is researched actively, and the field is advancing continually. We have probably only studied about one percent of all of the microbe species on Earth. Although microbes were first observed over three hundred years ago, the field of microbiology can be said to be in its infancy relative to older biological disciplines such as zoology and botany.

The MIT Biology Department core courses, 7.012, 7.013, and 7.014, all cover the same core material, which includes the fundamental principles of biochemistry, genetics, molecular biology, and cell biology. Biological function at the molecular level is particularly emphasized and covers the structure and regulation of genes, as well as, the structure and synthesis of proteins, how these molecules are integrated into cells, and how these cells are integrated into multicellular systems and organisms. In addition, each version of the subject has its own distinctive material.

Introductory Virology for 2nd and 3rd year courses
The material consists of a series of linked pages exploring an introduction to the concept of viruses, and an exploration of their general properties.

This site provides the basis of material for 7-lecture course in introductory microbiology (MCB2016F) and a 20-lecture course (MCB3024S, Defence and Disease) given to third-year students.

The MIT Biology Department core courses, 7.012, 7.013, and 7.014, all cover the same core material, which includes the fundamental principles of biochemistry, genetics, molecular biology, and cell biology. Biological function at the molecular level is particularly emphasized and covers the structure and regulation of genes, as well as, the structure and synthesis of proteins, how these molecules are integrated into cells, and how these cells are integrated into multicellular systems and organisms. In addition, each version of the subject has its own distinctive material. 7.014 focuses on the application of the fundamental principles toward an understanding of human biology. Topics include genetics, cell biology, molecular biology, disease (infectious agents, inherited diseases and cancer), developmental biology, neurobiology and evolution.

The MIT Biology Department core courses, 7.012, 7.013, and 7.014, all cover the same core material, which includes the fundamental principles of biochemistry, genetics, molecular biology, and cell biology. Biological function at the molecular level is particularly emphasized and covers the structure and regulation of genes, as well as, the structure and synthesis of proteins, how these molecules are integrated into cells, and how these cells are integrated into multicellular systems and organisms. In addition, each version of the subject has its own distinctive material. 7.014 focuses on the application of these fundamental principles, toward an understanding of microorganisms as geochemical agents responsible for the evolution and renewal of the biosphere and of their role in human health and disease.

The MIT Biology Department core courses, 7.012, 7.013, and 7.014, all cover the same core material, which includes the fundamental principles of biochemistry, genetics, molecular biology, and cell biology. Biological function at the molecular level is particularly emphasized and covers the structure and regulation of genes, as well as, the structure and synthesis of proteins, how these molecules are integrated into cells, and how these cells are integrated into multicellular systems and organisms. In addition, each version of the subject has its own distinctive material.7.014 focuses on the application of the fundamental principles toward an understanding of human biology. Topics include genetics, cell biology, molecular biology, disease (infectious agents, inherited diseases and cancer), developmental biology, neurobiology and evolution.

This is an interactive learning adventure for middle school students and has accompanying classroom activities and magazines. In this challenge, students will perform experiments to identify the germ responsible for a fungal disease. Students will follow rules or postulates worked out by Dr. Koch in the late 1800s for establishing whether a specific germ causes a particular infectious disease: 1. The suspected pathogen must be present in every case of the disease; 2. The suspected pathogen must be isolated from the host and grown in pure culture; 3. The disease must be reproduced when a pure culture of the suspected pathogen is inoculated into a healthy susceptible host; 4. The same pathogen must be recovered from the newly infected host. The Germ Theory of Disease holds that germs or microorganisms cause infectious diseases.

Funded through the National Center for Research Resources and the National Institute of Allergy and Infectious Diseases.

This is an interactive learning adventure for middle school students and has accompanying classroom activities and magazines. In Mission Three: Nemesis in Neuropolis, students learn about viruses and vaccines while investigating a smallpox case.

This workshop demonstrates on-line use of the national electronic bulletin board, complete with electronic mail started in 1987 by the National Association of Biology Teachers. Once on-line, 14 special interest areas are available, such as AP- Biology, magazine and book reviews, ABT Journal, NABT membership services, question and answer forum, software reviews, and swap/sale of used equipment. Also available for downloading onto your computer are extensive files of labs, graphics, and handouts. Discussions of this and other databases will emphasize the power of these new professional communication tools. Note: This workshop is not included in the published proceedings volume because it was not submitted by the author.