William F. Carman

Cellular immune correlates of protection against symptomatic pandemic influenza

The role of T cells in mediating heterosubtypic protection against natural influenza illness in humans is uncertain. The 2009 H1N1 pandemic (pH1N1) provided a unique natural experiment to determine whether crossreactive cellular immunity limits symptomatic illness in antibody-naive individuals. We followed 342 healthy adults through the UK pandemic waves and correlated the responses of pre-existing T cells to the pH1N1 virus and conserved core protein epitopes with clinical outcomes after incident pH1N1 infection. Higher frequencies of pre-existing T cells to conserved CD8 epitopes were found in individuals who developed less severe illness, with total symptom score having the strongest inverse correlation with the frequency of interferon-γ (IFN-γ)+ interleukin-2 (IL-2)− CD8+ T cells (r = −0.6, P = 0.004). Within this functional CD8+IFN-γ+IL-2− population, cells with the CD45RA+ chemokine (C-C) receptor 7 (CCR7)− phenotype inversely correlated with symptom score and had lung-homing and cytotoxic potential. In the absence of crossreactive neutralizing antibodies, CD8+ T cells specific to conserved viral epitopes correlated with crossprotection against symptomatic influenza. This protective immune correlate could guide universal influenza vaccine development.

Hepatitis B virus (HBV) and hepatitis C virus (HCV) infections in health care workers (HCWs): guidelines for prevention of transmission of HBV and HCV from HCW to patients

The transmission of viral hepatitis from health care workers (HCW) to patients is of worldwide concern. Since the introduction of serologic testing in the 1970s there have been over 45 reports of hepatitis B virus (HBV) transmission from HCW to patients, which have resulted in more than 400 infected patients. In addition there are six published reports of transmissions of hepatitis C virus (HCV) from HCW to patients resulting in the infection of 14 patients. Additional HCV cases are known of in the US and UK, but unpublished. At present the guidelines for preventing HCW to patient transmission of viral hepatitis vary greatly between countries. It was our aim to reach a Europe-wide consensus on this issue. In order to do this, experts in blood-borne infection, from 16 countries, were questioned on their national protocols. The replies given by participating countries formed the basis of a discussion document. This paper was then discussed at a meeting with each of the participating countries in order to reach a Europe-wide consensus on the identification of infected HCWs, protection of susceptible HCWs, management and treatment options for the infected HCW. The results of that process are discussed and recommendations formed. The guidelines produced aim to reduce the risk of transmission from infected HCWs to patients. The document is designed to complement existing guidelines or form the basis for the development of new guidelines. This guidance is applicable to all HCWs who perform EPP, whether newly appointed or already in post.

Real-time RT-PCR detection of 12 respiratory viral infections in four triplex reactions

1 d aboratory diagnosis of viral respiratory infection. However, hese methods are insensitive, laborious, have prolonged turnround times, and cannot detect all recognised viral respiraory pathogens. PCR is more sensitive and specific than traitional methods and can be used to detect fastidious viruses. eal-time PCR is at least as sensitive as nested gel-based CR protocols and offers increased rapidity (results availble within the working day). The use of specific labelled robes ensures easy interpretation when used in a multiplex ormat. We describe four triplex TaqManTM-based RT-PCR ethods adapted from published methods and further deeloped in-house for the diagnosis of 12 viral respiratory athogens.

Development of a real-time RT-PCR for the detection of Swine-lineage Influenza A (H1N1) virus infections

Abstract Background A novel influenza A virus, subtype H1N1 of swine-lineage (H1N1 swl) has transmitted rapidly to many regions of the world with evidence of sustained transmission within some countries. Rapid detection and differentiation from seasonal influenza is essential to instigate appropriate patient and public health management and for disease surveillance. Objectives To develop a rapid and sensitive real-time reverse transcriptase polymerase chain reaction (rtRT-PCR) for confirmation of H1N1 swl. Study design A one-step rtRT-PCR approach was employed to target the matrix gene of the novel influenza A/H1N1 swl and validated against a panel of seasonal influenza A (H1N1 and H3N2), swine influenza A/H1N1 and avian influenza A/H5N1 viruses. The assay following validation was then used prospectively to detect H1N1 swl positive specimens from the recent outbreaks in the UK and the Republic of Ireland. Results The one-step H1N1 swl matrix rtRT-PCR successfully detected H1N1 swl clinical specimens and did not cross-react with seasonal influenza A, subtypes H1N1 and H3N2 viruses and swine influenza A (H1N1). The H1N1 swl matrix assay did cross react with H5N1. The H1N1 swl matrix assay was then compared to two other assays using a dilution series and a panel of untyped influenza A positive clinical samples. These experiments found the assay to have a comparable sensitivity to the established universal influenza A rtRT-PCR and was more sensitive than the H1N1 swl specific assay that targeted the H1 region. Conclusions The results demonstrate that the rtRT-PCR is sensitive and should be used alongside existing universal influenza A assays to rapidly detect the novel H1N1 swl virus.

Practical experience of high throughput real time PCR in the routine diagnostic virology setting

Abstract The advent of PCR has transformed the utility of the virus diagnostic laboratory. In comparison to traditional gel based PCR assays, real time PCR offers increased sensitivity and specificity in a rapid format. Over the past 4 years, we have introduced a number of qualitative and quantitative real time PCR assays into our routine testing service. During this period, we have gained substantial experience relating to the development and implementation of real-time assays. Furthermore, we have developed strategies that have allowed us to increase our sample throughput while maintaining or even reducing turn around times. The issues resulting from this experience (some of it bad) are discussed in detail with the aim of informing laboratories that are only just beginning to investigate the potential of this technology.

Longitudinal study of genital infection by herpes simplex virus type 1 in western Scotland over 15 years

Although herpes simplex virus type 2 (HSV-2) is regarded as causing most cases of genital herpes, preliminary reports suggest that the type 1 virus (HSV-1) is increasingly the cause of infection.1 Recurrence rates, viral shedding, and the mode of acquiring HSV-1 infection are different from those for HSV-2, so counselling and clinical management strategies may need to be revised. We studied longitudinal trends in laboratory reports of genital HSV-1 infection. The West of Scotland Specialist Virology Centre processes 99% of all herpes simplex virus culture samples in the region. All genital samples of herpes simplex processed between 1 January 1986 and 31 December 2000 were reviewed for source of referral, patients sex and age (stratified into seven bands: ≤20, 21-25, 26-30, 31-35, 36-40, 41-45, and >45 years), and the type of virus isolated. Samples were cultured and then typed using fluorescein labelled monoclonal antibodies to HSV-1 …

Polymerase chain reaction for diagnosis of genital herpes in a genitourinary medicine clinic

Background: Polymerase chain reaction (PCR) has well established advantages over culture for diagnosis of herpes viruses, but its technical complexity has limited its widespread application. However, recent methodological advances have rendered PCR more applicable to routine practice. Aim: To compare automated PCR with viral culture for diagnosis of genital herpes. Methods: We studied 236 patients presenting with clinical features suggestive of genital herpes at an inner city genitourinary medicine clinic. Two swabs were taken from each patient. Cell culture and typing were performed by standard methods. Automated PCR was performed using the LightCycler instrument and the infecting viral type was determined by restriction endonuclease digestion of amplicons. Results: 109 patients (46%) had a positive test for herpes simplex virus (HSV). In 88, both PCR and culture were positive; in 21 PCR only was positive. With both detection methods, lesion duration and morphology were associated with HSV detection. Compared with culture alone, use of PCR increased sensitivity by 13.3% in specimens from vesicular lesions, by 27.4% from ulcerative lesions, and by 20.0% from crusting lesions. Conclusions: We advocate adoption of automated PCR as an efficient HSV detection and typing method for diagnosis of genital herpes in routine clinical practice. PCR allowed rapid laboratory confirmation of the diagnosis and increased the overall HSV detection rate by 24%.

Using multiplex real time PCR in order to streamline a routine diagnostic service.

Abstract An increasing number of virology laboratories are now utilising in house real time PCR assays as the frontline diagnostic tests. As the number of tests on offer increases the natural progression from this will be to rationalise their service via multiplexing. Since 2003 we have introduced a large number of qualitative and quantitative multiplex real time PCR assays into our routine testing service. This paper describes the development of the multiplex assays, the problems encountered and the resultant benefits to the routine service.

Reduction of Natural Killer but Not Effector CD8 T Lymphoyctes in Three Consecutive Cases of Severe/Lethal H1N1/09 Influenza A Virus Infection

Background The cause of severe disease in some patients infected with pandemic influenza A virus is unclear. Methodology/Principal Findings We present the cellular immunology profile in the blood, and detailed clinical (and post-mortem) findings of three patients with rapidly progressive infection, including a pregnant patient who died. The striking finding is of reduction in natural killer (NK) cells but preservation of activated effector CD8 T lymphocytes; with viraemia in the patient who had no NK cells. Comparison with control groups suggests that the reduction of NK cells is unique to these severely ill patients. Conclusion/Significance Our report shows markedly reduced NK cells in the three patients that we sampled and raises the hypothesis that NK may have a more significant role than T lymphocytes in controlling viral burden when the host is confronted with a new influenza A virus subtype.

Genotypic analysis of two hypervariable human cytomegalovirus genes

Most human cytomegalovirus (HCMV) genes are highly conserved in sequence among strains, but some exhibit a substantial degree of variation. Two of these genes are UL146, which encodes a CXC chemokine, and UL139, which is predicted to encode a membrane glycoprotein. The sequences of these genes were determined from a collection of 184 HCMV samples obtained from Africa, Australia, Asia, Europe, and North America. UL146 is hypervariable throughout, whereas variation in UL139 is concentrated in a sequence encoding a potentially highly glycosylated region. The UL146 sequences fell into 14 genotypes, as did all previously reported sequences. The UL139 sequences grouped into 8 genotypes, and all previously reported sequences fell into a subset of these. There were minor differences among continents in genotypic frequencies for UL146 and UL139, but no clear geographical separation, and identical nucleotide sequences were represented among communities distant from each other. The frequent detection of multiple genotypes indicated that mixed infections are common. For both genes, the degree of divergence was sufficient to preclude reliable sequence alignments between genotypes in the most variable regions, and the mode of evolution involved in generating the genotypes could not be discerned. Within genotypes, constraint appears to have been the predominant mode, and positive selection was detected marginally at best. No evidence was found for linkage disequilibrium. The emerging scenario is that the HCMV genotypes developed in early human populations (or even earlier), becoming established via founder or bottleneck effects, and have spread, recombined and mixed worldwide in more recent times. J. Med. Virol. 80:1615–1623, 2008.