E.O. Caul

Human enteric caliciviruses have a unique genome structure and are distinct from the Norwalk-like viruses

SummaryClassic human enteric caliciviruses (HuCVs) have a distinctive morphology and are primarily associated with pediatric acute gastroenteritis. Although morphologically distinct from the small round structured viruses (SRSVs), the classic HuCVs are thought to be closely related and were anticipated to have a similar genome organisation. We report the first genome sequence and molecular characterisation of a classic human enteric calicivirus associated with a case of acute vomiting and diarrhoea in an infant. The RNA genome (7266 nt) is smaller than the genome of SRSVs from the two genetic groups and has a unique arrangement of open reading frames. Further analysis of the 3′ terminal 3 kb from a second unrelated isolate confirmed this genomic organisation. Analysis of capsid and RNA polymerase sequences together with the unique genomic organisation of classic HuCV suggest these viruses are more closely related to the animal caliciviruses than the enteric SRSV group of viruses.

Further studies on human enteric coronaviruses.

SummaryComparisons were made between human enteric coronaviruses and the enteric coronaviruses of pigs and calves by negative staining.Examination of human intestinal organ culture fluids at various time intervals after inoculation with the human enteric coronavirus showed increasing numbers of particles in the fluids.Thin sections of the columnar epithelial cells of these explants showed a number of features consistent with the replication of known human and animal coronaviruses. Virus particles found in thin sections had a mean diameter of 68 nm. In addition, a structure was found in thin sections which has not been described previously. This structure may represent the viral nucleocapsid.

Seroepidemiology of human group C rotavirus in the UK.

The gene coding for the major inner capsid protein VP6 of human group C rotavirus was cloned into baculovirus using the pBlueBac2TM vector and expressed in insect cells. When cultured in High FiveTM cells, VP6 was expressed at a high level and exported to the cell culture medium. Purified VP6 was used to immunise rabbits. Hyperimmune rabbit serum, which reacted with native human group C rotavirus in infected cells, was used to develop and optimise an EIA for the detection of antibodies to group C rotavirus using the recombinant VP6 as a source of antigen. In a local epidemiological survey of 1000 sera grouped by age, an average of 43% of samples were found to have antibodies to human group C rotavirus with the highest proportion (66%) in the 71–75 year age group. In comparison, 97% of adults and 85% of children had antibodies to recombinant VP6 from the bovine RF strain of group A rotavirus. These results suggest that infection with human group C rotavirus is a common occurrence despite the apparent rarity of reports of human group C rotavirus in clinical samples from patients with gastroenteritis. J. Med. Virol. 52:86–91, 1997.

Replication of an Enteric Bovine Coronavirus in Intestinal Organ Cultures

SummaryA coronavirus isolated in tracheal organ cultures from the faeces of a calf with diarrhoea readily multiplied on passage in intestinal organ cultures. Evidence for multiplication was obtained by the production of viral haemagglutinin in organ culture fluids and the presence of immunofluorescence and viral particles in the columnar epithelial cells of the villi. Thus virus multiplication was studiedin vitro in the cell type in which it multiplies naturally.

Molecular cloning, sequence analysis and coding assignment of the major inner capsid protein gene of human group C rotavirus

The VP6 gene of human group C rotavirus was cloned and sequenced. Hybridization to the human group C and the porcine group C/Cowden dsRNA genomes assigned this coding sequence to segment 5. The complete human VP6 sequence contained an open reading frame of 1185 nucleotides (395 amino acids; deduced Mr 44,669 Da). The protein sequence demonstrated low homology with the group A VP6 sequences (41.7 to 42.7%) and high homology (88.9%) with the porcine group C VP6 sequence. However, the protein sequence alignments revealed a region of 10 amino acids that were significantly different between the human and the porcine group C viruses.

Hyperemesis hiemis—a sick hazard

Epidemic non-bacterial gastroenteritis or winter vomiting disease is a well recognized clinical syndrome causing significant morbidity in the general population and in semi-closed communities. The Norwalk group of viruses has become established as the aetiological agents responsible for this important clinical syndrome. As a result of their historically poorly-defined taxonomic status they have been alternatively described as small round structured viruses (SRSVs) which allow their differentiation from other morphologically distinct small round viruses, e.g. astroviruses, and classical human enteric caliciviruses. The Norwalk viruses are highly infectious, give rise to high secondary attack rates through person-to-person transmission and are common causes of outbreaks in hospitals leading to either ward or hospital closures. Transmission occurs via the faecal/oral route but also, and probably more importantly, from projectile vomiters, through environmental contamination. Inhalation of aerosolized virus arising from projectile vomiters is a possibility which requires further study. Laboratory diagnosis is currently achieved by electron microscopy but the recent molecular characterization of this group of viruses will allow the development of sensitive and specific assays. The future control of hospital outbreaks will rely heavily on effective control of infection procedures.

Early detection of cytomegalovirus (CMV) infection in bone marrow transplant patients by reverse transcription-PCR for CMV spliced late gene UL21.5: a two site evaluation

BACKGROUND Bone marrow transplant (BMT) patients at risk of developing cytomegalovirus (CMV) pneumonitis are identified routinely by the early detection of virus in blood. For early diagnosis of CMV infection, the RNA-based approach demonstrates advantages when compared with the current CMV antigen and DNA detection methods. OBJECTIVES We have evaluated our previously developed reverse transcription-polymerase chain reaction (RT-PCR) to a spliced late CMV gene (SLG; J. Virol. Methods 56 (1996), 139) to monitor CMV infection in BMT patients at two clinical sites. The diagnostic value of the SLG RT-PCR was compared with the routine CMV antigen and DNA detection methods. STUDY DESIGN Weekly blood samples from BMT patients were tested for CMV during the first 3 months post-transplant. The qualitative SLG RT-PCR, semiquantitative DNA PCR, and viral antigen tests were compared. The RNA and DNA PCR results were analysed in terms of their temporal relationship and consistency of CMV detection and compared with CMV infection diagnosed by viral antigen tests. RESULTS Of the 101 BMT recipients studied, 25 developed CMV antigenemia and/or DNAemia resulting in symptomatic infection in two patients. All CMV PCR-positive patients were either CMV seropositive pretransplant or received marrow from seropositive donor. The highest incidence of CMV infection was seen in seropositive recipients (R+) irrespective of the donors status. Detection of CMV infection by SLG RNA preceded CMV DNA detection by 0-2 weeks (median 1 week) and CMV antigen detection by 0-8 weeks (median 3 weeks). Once detected, the SLG RNA remained consistently positive before antiviral treatment was commenced. Both the SLG RNA and CMV DNA detection methods had the same clinical sensitivity, specificity, positive and negative predictive values of 100, 94, 80 and 100%, respectively. CONCLUSIONS The RT-PCR for SLG RNA proved to be the earliest indicator of CMV infection in BMT patients demonstrating a sustained pattern of CMV detection during the 3 months post-transplant period. Although very similar in its diagnostic performance to CMV DNA PCR the SLG RNA RT-PCR does not require quantitation and provides an efficient and ongoing indication of active CMV infection.

Absence of human astrovirus RNA in sewage and environmental samples

Over a period of several weeks during the summer of 1996, samples of sewage, sea water, river water, sand and silt were collected from a sewage works at Weston‐super‐Mare, England and from coastal areas nearby. A sensitive reverse‐transcriptase polymerase chain reaction (RT‐PCR) was used to search for human astrovirus (HAstV) RNA in concentrates of the samples. No evidence of astrovirus was found in any sample, which suggests that contamination with these viruses is not a problem in this area during the summer holiday season. Furthermore, the single case of astrovirus diarrhoea diagnosed in this laboratory in the summer occurred at the end of the sampling period, and not in the survey area. The primers used sometimes yielded a product two‐thirds the expected size but bearing no sequence homology with HAstV. The confirmation that poliovirus adsorbs to sand and silt shows that these materials might be able to concentrate other enteric viruses in water to a level which could be a threat to the health of people coming into contact with it.

Control of varicella-zoster infection on renal and other specialist units.

The introduction of chickenpox onto our renal unit recently raised several issues surrounding the management of patient and staff contracts. This paper describes the action taken and makes various recommendations for future management of similar cases. Guidelines are proposed for the management of patients and staff as well as the role of the infection control team in handling a chickenpox problem. Future developments, including the use of VZ vaccine for patient and staff, are also discussed.