Fatty acid composition of rubella virus and BHK21/13S infected cells

Lipid of white-spot syndrome virus originating from host-cell nuclei

The hypothesis that white-spot syndrome virus (WSSV) generates its envelope in the nucleoplasm is based on electron microscopy observations; however, as yet there is no direct evidence for this. In the present study, the lipids of WSSV and the nuclei of its host, the crayfish Procambarus clarkii, were extracted and the neutral lipid and phospholipid contents were analysed by high-performance liquid chromatography, thin-layer chromatography and gas chromatography/mass spectrometry. Phosphatidylcholine (PC) and phosphatidylethanolamine comprised 62.9 and 25.8 %, respectively, of WSSV phospholipids, whereas they comprised 58.5 and 30 %, respectively, of crayfish nuclei phospholipids. These two phospholipids were the dominant phospholipids, and amounts of other phospholipids were very low in the total WSSV and crayfish nuclei phospholipids. The data indicate that the phospholipid profile of WSSV and crayfish nuclei are similar, which is in agreement with the model that the lipids of WSSV are from the host-cell nuclei. However, the fatty acid chains of PC were different between the WSSV virions and crayfish nuclei, and the viral neutral lipid component was also found to be somewhat more complicated than that of the host nuclei. The number of species of cholesterol and hydrocarbon in virus neutral lipid was increased compared with that in host-cell nuclei neutral lipid. It is suggested that the differences between WSSV and its host are either due to selective sequestration of lipids or reflect the fact that the lipid metabolism of the host is changed by WSSV infection.

Altered membrane fatty acids of cultured human retinal pigment epithelium persistently infected with rubella virus may affect secondary cellular function

Persistent infection with rubella virus (RV) can alter secondary functions of host cells. Previously we had documented defective phagocytosis of latex beads by cultured human retinal pigment epithelial cells (RPE), persistently infected with M-33 RV (RPE/RV). Here, examining possible mechanisms for altered function, we reported significant differences between the total esterified fatty acids (FA) of RPE and RPE/RV membranes, measured by gas liquid chromatography. RPE/RV contained an increased proportion of saturated FA, particularly palmitic acid, with a presence of unusual chromatographic FA peaks co-eluting with odd-numbered long-chain carbon atom FA not normally found in human cells. Apical membrane microvilli, structures essential to phagocytic activity of RPE and RPE/RV, observed by scanning and transmission electron microscopy, were similar in number and appearance between uninfected RPE and RPE/RV cells before and after latex bead addition. However, RPE/RV microvilli, possibly reflecting altered membrane FA composition, engaged latex beads less effectively than uninfected RPE microvilli. In addition, microvilli remained abnormally distributed on RPE/RV cell surfaces at 48 h after latex addition. Thus, RV persistent infection may affect the cellular membrane fluidity and functional activity of human cells with increased saturated FA proportions and altered FA components of membrane phospholipids. These changes may participate in the defective phagocytosis of RPE/RV.

Molecular biology of rubella virus

This chapter summarizes the present medical significance of rubella virus. Rubella virus infection is systemic in nature and the accompanying symptoms are generally benign, the most pronounced being a mild rash of short duration. The most common complication of rubella virus infection is transient joint involvement such as polyarthralgia and arthritis. The primary health impact of rubella virus is that it is a teratogenic agent. The vaccination strategy is aimed at elimination of rubella and includes both universal vaccination of infants at 15 months of age with the trivalent measles, mumps, rubella (MMR) vaccine and specific targeting with the rubella vaccine of seronegative women planning pregnancy and seronegative adults who could come in contact with women of childbearing age, although it is recommended that any individual over the age of 12 months without evidence of natural infection or vaccination be vaccinated. Medically, the current challenge posed by rubella virus is to achieve complete vaccination coverage to prevent resurgences.

Arachidonic acid immunoregulation in lambs persistently infected with border disease virus

To evaluate arachidonic acid-related immunoregulatory mechanisms during long-term persistent pestivirus infection, we measured plasma contents of leukotriene C4 (LTC4), prostaglandin D2 (PGD2) and their plasma fatty acid (FA) precursor, arachidonic acid (AA), in six lambs with congenital border disease (BD). Significantly elevated average plasma LTC4 during the first half year of life was associated with increased PDG2 when compared to uninfected control lambs. Significantly elevated total plasma esterified AA stores suggest an effective BDV-mediated prostenoid immunostimulation. However, at 1 yr old, prostenoid secretion had fallen to normal (LTC4) or below normal (PGD2) levels. In contrast, there remained significantly elevated plasma esterified AA, present as available substrate for formation of these anti-viral immunoregulatory agents. These results suggested that preventing mobilization of AA from lipid stores for effective immune responses may be a viral strategy of BD virus that is associated with long term border disease effects.