Invasion

"The point is that this virus came to Earth three billion years ago," Sheila said. "At that time the Earth was a very different place. There was very little oxygen in the primitive atmosphere. Since then things have changed. The virus is still fine when it is in the latent form or even when it has been enabled and has transformed the cell. But if it is induced to form virions, it's destroyed by oxygen."

"Interesting idea," Harlan said. He looked down at the culture whose top was now off, exposing its surface to room air. "If that's the case then we'll see damaged, un-infective virus if we make another mount."

"That's exactly what I'm hoping," Sheila said.

Without wasting any time, Sheila and Harlan set to work creating a second sample. Pitt helped as best he could. Jonathan went back to playing with the computer-run security system.

When Harlan focused in on the new mount, it was immediately apparent that Sheila was right. The viruses appeared as if they had been partially eaten.

Sheila and Harlan jumped up from their seats and enthusiastically high-fived and then embraced each other. They were ecstatic.

"What a brilliant idea," Harlan said. "You're to be congratulated. It's a joy to see science in action."

"If we were doing real science," Sheila said, "we'd go back and exhaustively prove this hypothesis. For now, we'll just take it at face value."

"Oh, I agree," Harlan said. "But it makes such sense. It's amazing how toxic oxygen is and how few laypeople know it."

"I don't think I understand," Pitt said. "How does this help us?"

The smiles faded from Sheila's and Harlan's faces. They regarded each other for a beat, then retook their seats. Both were lost in thought.

"I'm not sure how this discovery is going to help us," Sheila said finally. "But it has to. I mean, it must be the alien Achilles' heel."

"It must have been the way that they lulled off the dinosaurs," Harlan said. "Once they decided to end the infestation, the viruses all went from being latent to being virions. Then bam! They hit the oxygen and all hell broke loose."

"That doesn't sound very scientific," Sheila said with a smile.

Harlan laughed. "I agree," he said. "But it gives us a hint. We have to induce the virus in the infected people to go from being latent to coming out of the cell."

"How is a latent virus induced?" Pitt asked.

Harlan shrugged. "A lot of ways," he said. "In tissue culture it's usually done with electromagnetic radiation like ultraviolet light or soft X rays like we used with the anaerobic bacterial culture."

"There are some chemicals that can do it," Sheila said.

"That's true," Harlan. "Some of the antimetabolites and other cellular poisons. But that doesn't help us. Neither do X rays. I mean it's not as if we could suddenly X-ray the planet."

"Are there regular viruses that are latent like the alien virus?" Pitt asked.

"Plenty," Sheila said.

"Absolutely," Harlan agreed. "Like the AIDS virus."

"Or the whole herpes viral group," Sheila said. "They can hide out for life or cause intermittent problems."

"You mean like cold sores?" Pitt asked.

"That's right," Sheila said. "That's herpes simplex. It stays latent in certain neurons."

"So when you get a cold sore it means that a latent virus has been induced to form virus particles?" Pitt asked.

"That's right," Sheila said with a touch of exasperation.

"I get cold sores every time I get a cold," Pitt said. "I suppose that's why they're called cold sores."

"Very clever," Sheila said sarcastically. "Pitt, maybe you should leave us alone while we brainstorm. This isn't supposed to be a teaching session."

"Wait a second," Harlan said. "Pitt just gave me an idea."

"I did?" Pitt questioned innocently.

"You know what is the best viral induction agent?" Harlan asked rhetorically. "Another viral infection."

"How is that going to help us?" Sheila asked.

Harlan pointed to the large freezer door across the room. ''In there we've got all sorts of viruses. I'm starting to think that we should fight fire with fire!"

"You mean start some kind of epidemic?" Sheila asked.

"That's exactly what I'm thinking," Harlan said. "Something extraordinarily infectious."

"But that freezer is full of viruses designed to be used as biological warfare agents. That will be like going from the frying pan into the fire."

"Hell, that freezer has everything from nuisance viruses to the most deadly," Harlan said. "We just have to pick one that's suitable."

"Well ... " Sheila mused. "It is true our original tissue culture was probably induced by the adenoviral vehicle we used for the DNA assay."

"Come on!" Harlan said. "Let me show you the inventory."

Sheila stood up. She was very dubious about fighting fire with fire, but she wasn't about to dismiss the idea out of hand.

Next to the freezer was a desk with a bookshelf over it. On the bookshelf were three large, black looseleaf notebooks. Harlan handed one each to Sheila and Pitt. He cracked open the third himself.