Cytoplasm. Cell organelles include mitochondria, chloroplasts in plants and ribosomes. Cytoplasm. Ribosomes present….Bacterial cells.

The vesicle fuses with a lysosome. The lysosome’s hydrolytic enzymes then destroy the pathogen. Figure: Lysosomes digest foreign substances that might harm the cell: A macrophage has engulfed (phagocytized) a potentially pathogenic bacterium and then fuses with a lysosomes within the cell to destroy the pathogen.

What Do Lysosomes Do? Lysosomes break down macromolecules into their constituent parts, which are then recycled. These membrane-bound organelles contain a variety of enzymes called hydrolases that can digest proteins, nucleic acids, lipids, and complex sugars. The lumen of a lysosome is more acidic than the cytoplasm.

Other organelles like endosomes and mitochondria are also exploited by different viruses during their cellular entry, uncoating, replication, and egress.

Organelles like mitochondria, ER, peroxisomes play an important role in innate immunity and host defence. Recently lipid droplets have also been reported to be essential for innate response against viral infection.

The scientists have uncovered that certain RNA viruses take control of a cellular enzyme to design a replication compartment on the cell’s membrane filled with PI4P lipids. Those lipids, in turn, allow the RNA viruses to attract and stimulate the enzymes they need for replication.

The reproductive cycle of viruses ranges from 8 hrs (picornaviruses) to more than 72 hrs (some herpesviruses). The virus yields per cell range from more than 100,000 poliovirus particles to several thousand poxvirus particles.

Bacteriophages — a name that literally means “bacteria-eating” — are viruses that target, infect, and destroy different strains of bacteria.

Viruses may cause disease but some can fall ill themselves. For the first time, a group of scientists have discovered a virus that targets other viruses.

Besides the cell membrane, the phages have another obstacle on their way out — a hard shell called cell wall that protects the bacteria. Only by destroying the cell wall can the phages release their offspring.

Two scientists contributed to the discovery of the first virus, Tobacco mosaic virus. Ivanoski reported in 1892 that extracts from infected leaves were still infectious after filtration through a Chamberland filter-candle. Bacteria are retained by such filters, a new world was discovered: filterable pathogens.

Dmitry Ivanovsky was still a student in 1887 when he began his work on the Tobacco Mosaic Disease (later to be renamed Tobacco Mosaic virus) that led to the first discovery of the virus.

In 1892, Dmitri Ivanovsky used one of these filters to show that sap from a diseased tobacco plant remained infectious to healthy tobacco plants despite having been filtered. Martinus Beijerinck called the filtered, infectious substance a “virus” and this discovery is considered to be the beginning of virology.

The Brain Boot Sector Virus Brain, the first PC virus, began infecting 5.2″ floppy disks in 1986. As Securelist reports, it was the work of two brothers, Basit and Amjad Farooq Alvi, who ran a computer store in Pakistan.

The term “malware” applies to viruses, worms, trojan horses, and spyware. The most expensive malware infection to date was the MyDoom worm, which resulted in roughly $38 billion of total damage.

The ILOVEYOU virus comes in an e-mail note with “I LOVE YOU” in the subject line and contains an attachment that, when opened, results in the message being re-sent to everyone in the recipient’s Microsoft Outlook address book and, perhaps more seriously, the loss of every JPEG, MP3, and certain other files on the …

Onel de Guzman

The man behind the world’s first major computer virus outbreak has admitted his guilt, 20 years after his software infected millions of machines worldwide. Within 24 hours, it was causing major problems across the globe, reportedly infecting 45 million machines. …

Twenty years on, the ILOVEYOU virus remains one of the farthest reaching ever. Tens of millions of computers around the world were affected. It also exposed vulnerabilities which we are still dealing with to this day, despite two decades of advances in computer security and technology.

While investigators were wary that those clues could be a smokescreen, the virus also communicated with a server hosted by the Manila-based Sky Internet, to which it sent passwords scraped from victims’ computers. Sky quickly took the server offline, which stopped at least part of the virus in its tracks.

Mydoom

The Melissa virus, reportedly named by Smith for a stripper in Florida, started by taking over victims’ Microsoft Word program. It then used a macro to hijack their Microsoft Outlook email system and send messages to the first 50 addresses in their mailing lists.

The Melissa virus was a mass-mailing macro virus released on or around March 26, 1999. As it was not a standalone program, it was not classified as a worm….Melissa (computer virus)

Hamza Bendelladj

It creates a new e-mail message to be sent to up to 50 addresses listed in the user’s MS Outlook address book. It gives the email message a subject line: “Important Message From USERNAME”, where USERNAME is taken from MS Word setting.

It is best simply to delete the email message. The Melissa worm replicates by sending multiple copies of itself to other recipients who execute the worm, enabling each of the copies to do the same. You, as an unsuspecting user, receive a message with an attached Word document that contains the macro.

The first known mobile virus, “Timofonica”, originated in Spain and was identified by antivirus labs in Russia and Finland in June 2000.

Once Conficker infects a computer, it disables many security features and automatic backup settings, deletes restore points and opens connections to receive instructions from a remote computer. Once the first computer is configured, Conficker uses it to gain access to the rest of the network.