L. Sinibaldi

Transplacental transmission of human polyomavirus BK

The presence of BK virus (BKV) and JC virus (JCV) in autopsy materials (placenta, brain, and kidney) of aborted fetuses was investigated by PCR using two sets of primers, specific for the regulatory region (RR) and for the capsid protein VP1, respectively. The RR of BKV was detected in 12 samples of placenta and brain and in nine samples of kidney obtained from 15 fetuses. Out of the 12 positive cases, four placentas, one brain, and three kidney samples also showed the presence of BKV DNA in the VP1 region. Of 12 placentas from a control group with a normal pregnancy outcome, the RR of BKV was detected in six samples, four of which were also positive for the VP1 region. None of the samples from either group was positive for the RR of JCV. In two cases, the nucleotide sequence of the BK RR demonstrated that the viruses isolated from maternal and fetal tissues showed a high homology with one another and had a characteristic deletion of the R63 box compared to the archetype strain. The results indicate that BKV may be transmitted vertically. J. Med. Virol. 56:372–376, 1998.

Detection of BK polyomavirus genotypes in healthy and HIV-positive children.

Urine samples from 211 community children (3–7 years age), from 33 HIV type-1 infected children and from 56 HIV- negative children were collected and analyzed for the presence of BK virus (BKV) DNA by PCR. PCR amplifications were carried out using primers specific for the BKV structural region VP1. We also investigated the distribution of BKV subtypes by a restriction fragment polymorphism assay (RFLP). We demonstrated BKV DNA in 3.8% of 211 community children with a higher prevalence of subtype I. In HIV-1 positive children we detected BKV DNA in 2 urine samples (6%) out of 33, both belonging to subtype I. The HIV-negative cluster did not show any positivity to BKV DNA. The results confirm a more frequent primary BKV infection in children of 3–5 years of age and a higher prevalence in hospitalized children affected by HIV-1. The most relevant finding was that among both the community and HIV-1 positive children the subtype I was the most frequently detected.

Metal complexes of lactoferrin and their effect on the intracellular multiplication of Legionella pneumophila

The action of bovine lactoferrin saturated with iron, zinc and manganese on the intracellular multiplication of Legionella pneumophila in HeLa cells has been tested. The results obtained showed that lactoferrin did not influence the invasive efficiency of Legionella. The intracellular multiplication of the bacterium was inhibited by apo-lactoferrin and by lactoferrin saturated with manganese and zinc, whereas lactoferrin saturated with iron enhanced the intracellular growth. Experiments in parallel were performed with iron, manganese and zinc citrate to test the effect due to the metal ions alone. Even in this condition the addition of an iron chelate enhanced the multiplication of Legionella while the manganese chelate produced a certain inhibition.

Involvement of gangliosides in the interaction between BK virus and Vero cells

SummaryBK virus infectivity was inhibited by gangliosides extracted from Vero cells and by standard preparations of different gangliosides. Gangliosides were also able to restore the susceptibility of glycosidase-treated Vero cells to BK virus infection.

Inhibition of BK Virus Haemagglutination by Gangliosides

The effect of gangliosides extracted from human group O Rh+ erythrocytes on haemagglutination by BK virus was investigated. Experiments were performed on both ganglioside mixtures and isolated fractions separated by column chromatography and characterized by thin-layer chromatography. These results were compared with those obtained with standard preparations of gangliosides, and the inhibiting activity was shown to be confined mainly to gangliosides with a RF lower than GM1. It was also observed that the insertion of gangliosides in liposomes increased the haemagglutination-inhibiting activity and that ganglioside coating restored the ability of glycosidase-treated human red blood cells to agglutinate.

Identification of a new control region in the genome of the DDP strain of BK virus isolated from PBMC

The various strains of human polyomavirus BK (BKV) show a marked heterogeneity in the noncoding control region (NCCR), which includes the origin of replication and the regulatory region for early and late transcription. A new BKV strain (DDP, U91605) was identified by direct detection and sequencing of PCR products of BKV‐NCCR DNA obtained from PBMC samples of HIV‐positive or ‐negative subjects. The DDP strain NCCR sequence showed an organisation not described previously in vivo with the maximum homology with the archetypal strain (WW) (M34048), as compared with those collected in GenBank. Structurally, P68, Q39, and S68 boxes were perfectly conserved, whereas the R63 box was completely deleted. This deletion involves the loss of sequences able to bind cellular factors essential for the DNA transcription, such as NF1 binding sites, normally present twice in the R box and the modification of SP1. It is possible that these rearrangements represent a cause of the loss of the VP1 region observed in 9/22 PBMC samples and never observed in urine isolates, which are similar to the WW strain. J. Med. Virol. 58:413–419, 1999.

Effect of monensin on the invasiveness and multiplication of Legionella pneumophila

The polyether antibiotic monensin exhibited bacteriostatic activity against a clinical isolate of Legionella pneumophila in vitro. Experiments designed to test the effect of the compound on the invasiveness and multiplication of L. pneumophila in HeLa cells showed that, in the presence of the antibiotic, legionellas that penetrated the cells did not multiply. However, monensin did not alter the characteristics of phagosomes that contained ingested legionellas. In the presence of monensin, infected cells exhibited extensive vacuolation and a noticeable reduction in the number of intracellular micro-organisms was evident a few hours after infection.

VSV binding to lipids from different cell lines

SummaryGangliosides from different cells were tested for their inhibiting activity on VSV attachment to CER cells and goose erythrocytes.This inhibiting activity was enhanced when gangliosides were inserted into liposomes, in particular if containing phosphatidylserine.

Multiplication of Legionella pneumophila in HeLa cells in the presence of cytoskeleton and metabolic inhibitors

A study has been carried out on the action of cytoskeleton and metabolic inhibitors on intracellular multiplication in HeLa cells of a virulent strain of Legionella pneumophila serogroup 6. The effects of the substances were separately tested on both penetration and intracellular multiplication of L. pneumophila. Only cytochalasin A and 2‐deoxy‐d‐glucose (2dG) affected bacterial internalisation, whereas intracellular multiplication was inhibited by cytochalasins A, B, C, D and J (D being the most active) and by 2dG with a dose‐response effect. The action of 2dG was counteracted by 50 mM glucose. Experiments carried out with cytochalasin D and a rhodamine‐phalloidin conjugate showed the involvement of cytoskeletal elements in intracellular multiplication of Legionella; compounds acting on microtubules had no effect.

Effect of Sub-Inhibitory Concentrations of Antibiotics on the Hemolytic Activity of Legionella

The effect of sub-inhibitory concentrations of various antibiotics on the hemolytic activity of different strains of Legionella has been tested. By means of a gradient plate technique it was possible to demonstrate that in a limited range of sub-inhibitory concentrations, antibiotics did not affect bacterial growth but inhibited the hemolytic activity of the strains examined.