A virus may be mutated.Logical formLearned from46 sentences. A (bird flu virus) may kill some persons.Logical formLearned from46 sentences. A virus may cause (deficiency syndrome).Logical formLearned from46 sentences. Diseases may be caused by viruses.Logical formLearned from45 sentences. A virus may remain in a body.Logical formLearned from45 sentences. A virus may spread through contact.Logical formLearned from45 sentences. Viruses can be contagious.Logical formLearned from45 sentences. A strain may pertain-to an avian (influenza virus).Logical formLearned from45 sentences. A virus can be in a vaccine.Logical formLearned from45 sentences. Questions can be about a virus.Logical formLearned from45 sentences. Some viruses can be spyware.Logical formLearned from45 sentences. A person may catch a virus.Logical formLearned from45 sentences. A virus may undergo mutations.Logical formLearned from45 sentences. Copies may pertain-to a virus.Logical formLearned from45 sentences. A response can be to a virus.Logical formLearned from45 sentences.