Researchers Launch a Web-Based Resource for Smallpox Research

POXVIRUS RESOURCE CENTER

An important component of this federal initiative is the development of an online genomics and bioinformatics resource center, funded by the National Institute of Allergy and Infectious Disease, to foster research on smallpox and other poxviruses, such as vaccinia and monkeypox. The project, which is being overseen by investigators at the University of Alabama at Birmingham (UAB) and St Louis University in Missouri, will feature repositories of genetic information about poxviruses, information that will be freely available to anyone with Web access.

As a start, the site (http://www.genome.uab.edu/pox/) provides access to information about a dozen complete genomes of poxviruses, such as variants of vaccinia (the strain used to make the smallpox vaccine), two strains of variola major, fowlpox, and others.

"Ultimately, we intend to have a portal set up [at UAB] that has links to various resources," said UAB microbiologist Elliot Lefkowitz, PhD, who is one of the two lead investigators on the $3.6 million project. Some of the links will be to databases such as GenBank, the National Institutes of Health genetic sequence database, which is an annotated collection of all publicly available DNA sequences, including those deposited with two other databases, the DNA DataBank of Japan and the European Molecular Biology Laboratory.

Another aspect of the project involves determining the DNA sequence of a variety of poxviruses, including additional variants of the smallpox virus, explained David Buller, PhD, of St Louis University, the other lead investigator.

"We're going to do some sequencing of other orthopox viruses that are useful as models for testing antivirals, and we're also going to sequence some of the strains of monkeypox," said Buller.

A POX ON THEIR HUTCHES

One of the viruses that Buller's lab will sequence is rabbitpox, a virus that is believed to have evolved from vaccinia. Rabbitpox suddenly appeared at about the same time in two laboratory rabbit colonies, at universities in New York and Amsterdam. Like smallpox (but unlike vaccinia), rabbitpox is virulent via an aerosol route, so that a single infected rabbit could quickly infect a room full of animals.

Buller noted that his laboratory is sequencing the rabbitpox virus for two reasons. "Rabbitpox in rabbits is another good model for testing antivirals," he said. "And by comparing the genetic strain of rabbitpox with vaccinia, which is where we think rabbitpox came from, we might find some clues as to what happened to make it so virulent by the aerosol route."

Collaborators at the CDC will sequence variants of the smallpox virus. In the United states, hands-on work with smallpox is allowed to be conducted only at the CDC for reasons of security and safety. In addition, collaborators at the US Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Md, where researchers are working on the development of antiviral drugs for smallpox, will sequence strains of monkeypox.

Having information about the DNA sequences of various strains of viruses will provide invaluable data that can be used in developing antivirals and vaccines. For example, researchers working to develop a drug that targets a specific viral enzyme will be able to look for gene sequences that are highly conserved from strain to strain—indicating that those sequences are important for the virus to function. Drugs based on such genetically conserved targets are more likely to be active against various viral strains and less likely to be foiled by the development of resistance mutations.

Studying these viruses at the molecular level may also help researchers gain a better understanding of such important issues as virulence. Monkeypox, for example, is found in monkeys and squirrels in African rain forests, but it also can infect humans. When it does, it results in a disease that is similar to smallpox and can be fatal.

"What monkeypox doesn't do very well is spread in human populations," said Buller. "One of the goals [of the project] is to try to understand if there is a potential for monkeypox to evolve into a better human pathogen." Although smallpox vaccine protects against monkeypox, few people in Africa have been immunized, or immunized recently enough, to have that protection.

"Because there's a lot more access to rain forests by people [in Africa], and no vaccine program in place to protect the population from smallpox, these people are susceptible to infection by monkeypox," he said.

ANNOTATING GENES

Another aspect of the project is to enhance the repository of raw genetic sequences of the poxvirus strains by annotating this data with what researchers already know about the various viral genes and their functions. Paula Traktman, PhD, of the Medical College of Wisconsin, Milwaukee, is overseeing this aspect of the work, which will involve combing the literature and contacting laboratories around the world to gather as much information about each of the poxvirus genes as possible, said Lefkowitz.

"In essence, we'll have little minireviews of each gene," he said. Other project collaborators, at the University of Victoria, British Columbia, are developing software that will allow researchers to analyze genomes of variola and other poxviruses to glean information from the DNA sequences, explained Buller. A better understanding of this family of viruses at the genetic level will help researchers apply what they learn from animal studies to human threats, such as smallpox and monkeypox. What researchers learn about the function of genes in one type of poxvirus often can be applied to those genes' counterparts in smallpox, especially if the genes are highly conserved through evolution.

A recent alarming report from Australian researchers who inadvertently created a deadly mousepox virus underscores the need for this type of research, said Lefkowitz. As part of research aimed at creating a contraceptive vaccine for pest control, the investigators spliced a gene for interleukin 4 into a viral vector, the mousepox virus. Instead of having the desired effect, the modified virus killed all the test mice within 9 days and made vaccines that normally protect mice against mousepox less effective, the researchers report in this month's issue of the Journal of Virology.

However, it doesn't necessarily take a scientist—or a bioterrorist—skilled in genetic engineering to put human genes into poxviruses, because these viruses can pick up host genes on their own, Lefkowitz noted.

"So whether it happens naturally, or whether it happens by accident in the laboratory, or whether it happens on purpose by some group trying to develop a new disease agent, the more we know about these viruses in general, the more we know about the possibilities—and how to respond," he said.