Human Protoparvovirus DNA and IgG in Children and Adults with and without Respiratory or Gastrointestinal Infections

Three human protoparvoviruses, bufavirus (BuV), tusavirus (TuV) and cutavirus (CuV), have recently been discovered in diarrheal stool. BuV has been associated with diarrhea and CuV with cutaneous T-cell lymphoma, but there are hardly any data for TuV or CuV in stool or respiratory samples. Hence, using qPCR and IgG enzyme immunoassays, we analyzed 1072 stool, 316 respiratory and 445 serum or plasma samples from 1098 patients with and without gastroenteritis (GE) or respiratory-tract infections (RTI) from Finland, Latvia and Malawi. The overall CuV-DNA prevalences in stool samples ranged between 0–6.1% among our six patient cohorts. In Finland, CuV DNA was significantly more prevalent in GE patients above rather than below 60 years of age (5.1% vs 0.2%). CuV DNA was more prevalent in stools among Latvian and Malawian children compared with Finnish children. In 10/11 CuV DNA-positive adults and 4/6 CuV DNA-positive children with GE, no known causal pathogens were detected. Interestingly, for the first time, CuV DNA was observed in two nasopharyngeal aspirates from children with RTI and the rare TuV in diarrheal stools of two adults. Our results provide new insights on the occurrence of human protoparvoviruses in GE and RTI in different countries.     

Possible Dual Function of M Protein: Resistance to Bacteriophage A25 and Resistance to Phagocytosis by Human Leukocytes

Spontaneous phage A25-resistant (A25(R)) mutants of group A streptococci, strain K56, were isolated. The mutant cultures were unable to adsorb phage particles and hyperproduced M protein. Trypsin-digested A25(R) cells regained the ability to adsorb phage particles, but failed to become infectious centers. This failure indicated that the mutation created a double barrier to phage growth: (i) receptors were masked by M protein; (ii) irreversibly adsorbed phage were unable to multiply. Spontaneous variants of one A25(R) mutant, shown to be M negative (M(-)) by electron microscopy, serological tests, and sensitivity to phagocytosis, rapidly adsorbed phage and were able to become infectious centers. Therefore, it was concluded that the mutant phenotype, A25(R), arose by a single mutation and genes coding for this trait and M protein synthesis were either genetically linked, controlled by a common gene or were biochemically interdependent. The A25(R) phenotype was unstable and, as expected for plasmid-coded properties, acridine orange induced segregation of this phenotype. The parental M(+), A25-sensitive (A25(S)) cultures proved to be a mixed population. Infection at various multiplicities indicated that this culture was composed of phage A25(S) cells and cells more resistant to infection. Morphological comparison of thin sections of A25(R) and A25(S) cells by electron microscopy demonstrated striking differences. The A25(R) culture was composed entirely of cells uniformly covered with M protein, whereas the A25(S)M(+) wild-type culture was a mixed population, the majority of cells devoid of M protein. Phagocytosis by human blood enriched the culture for the latter cell type, suggesting that differences in phage sensitivity in the wild-type culture were also determined by the presence or absence of M protein. Thus M protein can serve a dual function for the streptococcal cell by allowing it to avoid infection by bacteriophage and ingestion by human leukocytes.     

Effect of metabotropic glutamate receptor activation on receptor-mediated cyclic AMP responses in primary cultures of rat striatal neurones

Co-activation of group I metabotropic glutamate (mGlu) receptors and adenosine receptors resulted in an augmented cyclic AMP response in primary cultures of rat striatal neurones. -glutamate and the selective group I agonist, (S)-dihydroxyphenylglycine (S-DHPG) evoked concentration-dependent potentiations of cyclic AMP accumulation stimulated by the adenosine receptor agonist, 5′-N-ethylcarboxamidoadenosine (NECA), with EC₅₀ values of 3.41±0.39 and 5.69±1.64 μM, respectively, and maximal augmentations of approximately 350% at concentrations of 100 μM. The S-DHPG potentiation was inhibited by group I mGlu receptor antagonists and a protein kinase C inhibitor, Ro 31-8220, implicating products of PI hydrolysis in this effect. Furthermore, -glutamate and S-DHPG stimulated PI hydrolysis in striatal neuronal cultures with similar EC₅₀ values to those observed for the augmentation of NECA cyclic AMP responses (5.19±1.18 and 3.78±1.42 μM, respectively). In situ hybridization and immunofluorescence techniques indicate that group I mGlu receptor-evoked potentiations are likely to be mediated via mGlu₅ receptors, which are expressed at high levels in these cultures. In contrast to cross-chopped slices of neonatal rat striatum, of equivalent age, the group II mGlu receptor agonist, (2S,2′R,3′R)-2-(2′,3′-dicarboxycyclopropyl)glycine (DCG-IV) was without effect on NECA- or forskolin-stimulated cyclic AMP responses in primary striatal neuronal cultures. This lack of effect might be due to a low level of expression of group II mGlu receptors in cultured striatal neurones.     

Oropharyngeal malignant epithelial cell, lymphocyte and macrophage CD44 surface receptors for hyaluronate are expressed in sustained EBV infection: Immunohistochemical data and EBV DNA tissue indices

The role of CD44 in Epstein-Barr virus (EBV)-related epithelial tumors is poorly understood. We studied the expression of CD44 in EBV infection in patients with oral squamous cell carcinoma (SCC) and nasopharyngeal carcinoma (NPC) and measured the EBV DNA. Whole blood, plasma and tissue samples from 8 male and 2 female patients with oral SCC, NPC, salivary gland lymphoepithelioma, normal salivary gland and buccal mucosa were assayed for EBV DNA. Expression of CD44, latent membrane protein (LMP), and labeling of lymphocytes, macrophages and dendritic cells were estimated by immunohistochemistry. Tissue EBV DNA was detected in 7 of 8 cases (87.5%) of oral malignant, benign and border-line lesions. LMP expression levels in tumors varied from absence and minimal to moderate - 50.3, 43.6, 6.0% and 91.1, 6.7, 2.2% for SCC and NPC, respectively. Levels of CD44 positivity in neoplasms were minimal (15.5 and 16.7%), moderate (30.3 and 47.8%), and diffuse (54.2 and 35.5%) for SCC and NPC, respectively, thus deviating from normal oral mucosa revealing heavily stained (100.0%) epithelial contours. CD19-positive B lymphocytes and S100-positive dendritic cells were intermixed with neoplastic cells. Collectively, CD44 mediated signaling may be implicated in EBV infection associated with the pathogenesis of oral SCC and NPC.