This variant potentiates a less vigorous CTL response in the immune system, and thus can ultimately persist in the host organism indefinitely. The latter is referred to as chronic (Clone 13) LCMV infection.LCMV is a spherical enveloped virus with a diameter between 60 and 300 nm. The helical nucleocapsid contains an RNA genome consisting of two negative single-stranded RNA segments. The negative RNA strand, complementary to the necessary mRNA strand, indicates that it must first be transcribed into a positive mRNA strand before it can be translated into the required proteins. The L strand is ambisense RNA, encoding multiple proteins in opposite directions, separated by an intergenic region. It is approximately 7.2 kb in size and encodes a high-molecular-mass protein (L; 200 kDa) and an 11 kDa small polypeptide Z with unknown function and a ring finger motif. The viral RNA-dependent RNA polymerase is encoded by the L protein which contains conserved characteristic motifs throughout all the RNA-dependent, RNA-polymerases. The S strand is ambisense and approximately 3.4 kb in size. It encodes the two main structural proteins: nucleo-protein (NP) (63 kDa) and glycoprotein precursor complex (GPC) (75kDa). The latter undergoes posttranslational cleavage at two separate steps: first in the endoplasmic reticulum, where following translation on the membrane, the stable signal peptide region is cleaved by signal peptidase (SPase); notably, this signal peptide is retained, in contrast to other viruses.
Lymphocytic choriomeningitis (LCM) is a rodent-borne viral infectious disease that presents as aseptic meningitis, encephalitis or meningoencephalitis. Its causative agent is lymphocytic choriomeningitis mammarenavirus (LCMV), a member of the family Arenaviridae. The name was coined by Charles Armstrong in 1934.Lymphocytic choriomeningitis (LCM) is "a viral infection of the membranes surrounding the brain and spinal cord and of the cerebrospinal fluid". The name is based on the tendency of an individual to have abnormally high levels of lymphocytes during infection. Choriomeningitis is "cerebral meningitis in which there is marked cellular infiltration of the meninges, often with a lymphocytic infiltration of the choroid plexuses". Signs and symptoms
LCMV infection manifests itself in a wide range of clinical symptoms, and may even be asymptomatic for immunocompetent individuals. Onset typically occurs between one or two weeks after exposure to the virus and is followed by a biphasic febrile illness. During the initial or prodromal phase, which may last up to a week, common symptoms include fever, lack of appetite, headache, muscle aches, malaise, nausea, and/or vomiting. Less frequent symptoms include a sore throat and cough, as well as joint, chest, and parotid pain. The onset of the second phase occurs several days after recovery, and consists of symptoms of meningitis or encephalitis. Pathological findings during the first stage consist of leukopenia and thrombocytopenia.