Detection of Avocado Sunblotch and Other Viroids Using RNA Filter Paper Capture and RT-PCR.

This method originated due to the need to quickly and sensitively detect Avocado sunblotch viroid (ASBVd) in nursery and field trees in California. Optimum sampling protocols were developed for leaf collection from different sized trees based on size and branching as well as for fruit. An ethanol containing buffered extract from 1 g of ground leaf tissue was used as the source of RNA. The extract was absorbed onto small pieces (disks) of Whatman No. 1 filter paper which were then washed and dried. RNA was eluted from the filter paper using sterile water and used as a template in a standard single-tube RT-PCR reaction. The RNA adsorbed on the filter paper disks was quite stable, and the disks could be stored for over 1 year and shipped worldwide at ambient temperature with no noticeable decline in the quality or quantity of the resulting RT-PCR products. The filter paper capture method was expanded to the detection of other viroids including Potato spindle tuber viroid, Peach latent mosaic viroid, and Chrysanthemum stunt viroid and was tested with some viruses as well with minor modifications of the standard protocol.

Prediction of stillbirth: an umbrella review of evaluation of prognostic variables.

BACKGROUND: Stillbirth accounts for over 2 million deaths a year worldwide and rates remains stubbornly high. Multivariable prediction models may be key to individualised monitoring, intervention or early birth in pregnancy to prevent stillbirth. OBJECTIVES: To collate and evaluate systematic reviews of factors associated with stillbirth in order to identify variables relevant to prediction model development. SEARCH STRATEGY: MEDLINE, Embase, DARE and Cochrane Library databases and reference lists were searched up to November 2019. SELECTION CRITERIA: We included systematic reviews of association of individual variables with stillbirth without language restriction. DATA COLLECTION AND ANALYSIS: Abstract screening and data extraction were conducted in duplicate. Methodological quality was assessed using AMSTAR and QUIPS criteria. The evidence supporting association with each variable was graded. RESULTS: The search identified 1198 citations. Sixty-nine systematic reviews reporting 64 variables were included. The most frequently reported were maternal age (n = 5), body mass index (n = 6) and maternal diabetes (n = 5). Uterine artery Doppler appeared to have the best performance of any single test for stillbirth. The strongest evidence of association was for nulliparity and pre-existing hypertension. CONCLUSION: We have identified variables relevant to the development of prediction models for stillbirth. Age, parity and prior adverse pregnancy outcomes had a more convincing association than the best performing tests, which were PAPP-A, PlGF and UtAD. The evidence was limited by high heterogeneity and lack of data on intervention bias. TWEETABLE ABSTRACT: Review shows key predictors for use in developing models predicting stillbirth include age, prior pregnancy outcome and PAPP-A, PLGF and Uterine artery Doppler.

Effects of oral probiotic supplements on vaginal microbiota during pregnancy: a randomised, double-blind, placebo-controlled trial with microbiome analysis.

OBJECTIVE: To determine the effects on the vaginal microbiota of an oral probiotic preparation administered from early pregnancy. DESIGN: Randomised, double blind, placebo-controlled trial. SETTING: Four maternity units in the UK. POPULATION: Women aged 16 years or older recruited at 9-14 weeks' gestation. METHODS: Participants were randomly allocated to receive oral capsules of probiotic containing Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 each at 2.5 × 109 colony-forming units (CFUs) or placebo once daily from recruitment until the end of pregnancy. MAIN OUTCOME MEASURE: Rates of bacterial vaginosis (BV, defined as Nugent score ≥7) at 18-20 weeks' gestation compared by logistic regression adjusted for possible confounders. RESULTS: The primary analysis included 78% (238/304) of participants who initially consented (probiotic group 123, placebo group 115). Of these participants, 95% (227/238) reported an intake of 93% or more of the required number of capsules. The rates of BV did not differ between groups at 18-20 weeks' gestation (15% (19/123) in the probiotic group vs. 9% (10/115) in the placebo group, adjusted odds ratio 1.82, 95% confidence interval 0.64-5.19). There were also no differences between the groups in the proportion of women colonised with the probiotic strains, Escherichia coli, group B streptococci or other vaginal microbiota. There were no differences in the alpha diversity or composition of the bacterial communities between or within the probiotic and placebo groups at 9-14 and 18-20 weeks' gestation. CONCLUSIONS: Oral probiotics taken from early pregnancy did not modify the vaginal microbiota. TWEETABLE ABSTRACT: The oral probiotic preparation used in this study does not prevent BV in pregnant women.

The Global Genome Biodiversity Network (GGBN) Data Standard specification.

Genomic samples of non-model organisms are becoming increasingly important in a broad range of studies from developmental biology, biodiversity analyses, to conservation. Genomic sample definition, description, quality, voucher information and metadata all need to be digitized and disseminated across scientific communities. This information needs to be concise and consistent in today's ever-increasing bioinformatic era, for complementary data aggregators to easily map databases to one another. In order to facilitate exchange of information on genomic samples and their derived data, the Global Genome Biodiversity Network (GGBN) Data Standard is intended to provide a platform based on a documented agreement to promote the efficient sharing and usage of genomic sample material and associated specimen information in a consistent way. The new data standard presented here build upon existing standards commonly used within the community extending them with the capability to exchange data on tissue, environmental and DNA sample as well as sequences. The GGBN Data Standard will reveal and democratize the hidden contents of biodiversity biobanks, for the convenience of everyone in the wider biobanking community. Technical tools exist for data providers to easily map their databases to the standard.Database URL: http://terms.tdwg.org/wiki/GGBN_Data_Standard.

Non-anaemic iron deficiency in pregnancy: the views of health service users and health care professionals.

BACKGROUND: The prevalence of anaemia in pregnancy in Europe is 25% and that resulting from iron deficiency is estimated at 40%. The maternal and fetal morbidity of non-anaemic iron deficiency (NAID) in pregnancy is likely to be significant. OBJECTIVES: To determine the views and opinions of health service users and clinicians concerning NAID in pregnancy in order to inform future research. METHODS: Two semi-structured focus groups were carried out to determine health service users' views on anaemia and NAID in pregnancy. A questionnaire was administered to obstetricians, haematologists, midwives and anaesthetists to elucidate their views on NAID in pregnancy. RESULTS: The study indicated that health service users and clinicians were interested in implementing testing for NAID in pregnancy with serum ferritin, if proven to be effective at reducing the effects of anaemia and improving maternal and neonatal outcomes. Clinicians had reservations in the use of intravenous iron supplementation for NAID in pregnancy. CONCLUSION: NAID is now accepted as a target condition for research by health service users and clinicians. The focus of future research should be on screening for NAID and its treatment.

New resources to address antibiotic resistance are just a click away.

Antibiotic resistance is a complex issue with multiple causes, and there are many roles to play in addressing it. As part of its response, the Public Health Agency of Canada is launching a pilot antibiotic awareness campaign for Canadian families and health care professionals. Coinciding with Antibiotic Awareness Week, starting on November 17, 2014, the goal of this campaign is to improve knowledge and awareness of antibiotic resistance in Canada. To achieve this, the Agency has developed a suite of resources for both Canadian families and health care providers featuring a variety of key messages explaining antibiotic resistance, why it is important, and how to reduce the risks associated with it. Resources for Canadian families include an online informational video, an educational brochure, and infographics for both adults and children. Resources for health care professionals include two online Continuing Medical Education Modules, a letter that physicians can sign and provide to parents explaining why an antibiotic was not prescribed, and two webinars to present trends in antimicrobial resistance (AMR) and antimicrobial use. Health professionals will also receive an electronic postcard and a bilingual campaign poster. Promoting the campaign messages and using these campaign resources will support health professionals in discussions about antibiotic resistance with their patients or clients, and in their continuing efforts to be part of the solution in addressing this important global health challenge.

BRIEF - SYNOPSIS OF THE HUMAN IMMUNODEFICIENCY VIRUS (HIV) SCREENING AND TESTING GUIDE.

BACKGROUND The Public Health Agency of Canada (PHAC) estimates that, in 2011, 25% of people living with HIV in Canada were undiagnosed. Hesitation to seek testing may arise from fear, stigma and discrimination associated with the HIV diagnosis and related risk behaviours. This guide is designed to complement existing efforts to support care providers involved in HIV testing, in order to reduce the number of undiagnosed HIV infections in Canada. APPROACH PHAC commissioned a literature review and consulted with provinces and territories, and key stakeholders, including people living with HIV/AIDS, academics, nurses, physicians, professional associations, non-governmental organizations, policy-makers, community workers, and legal and ethical experts. As a result, the recommendations outlined in the guide are based on the most up-to-date evidence and expert opinion. SCREENING AND TESTING GUIDE The consideration and discussion of HIV testing should be made a component of routine periodic medical care. Offering HIV testing routinely can help normalize testing, and address the multiple barriers to reducing the number of undiagnosed cases in Canada. Begin with a brief explanation to the client on how HIV is transmitted: through unprotected sex, the sharing of drug-use equipment, and from a pregnant mother to her child. Clients can then consider their own situation and indicate whether they would like to have an HIV test. Upon request, a risk assessment may be conducted. As with other tests, testing is voluntary and verbal consent is sufficient. Negative test results provide an opportunity to remind clients of those practices that can help them maintain an HIV-negative status. There are a range of referrals and resources available to assist clients in reducing at-risk activities and maintaining a negative status. Those who are part of a couple should be encouraged to discuss HIV testing with their partners so they're not unknowingly involved in a serodiscordant relationship. Positive test results should always be provided in person and ideally by the initial care provider who has information resources and support referrals at the ready. An HIV positive diagnosis can be difficult news; it is important to take the time to discuss the results and answer any questions the client might have. Focus on positive messages by highlighting advances in HIV care, treatment and support. Note that HIV is now considered a chronic illness, and people living with HIV can live long, active and healthy lives. Advise the client about strategies for managing HIV and link them to care. Provide risk reduction information to prevent transmission Make the client aware that positive test results will be shared confidentially with the local public health department, which can assist in notifying previous and current partners of the need to be tested while protecting the client's anonymity and privacy. Strategies for informing past, current and future partners can be reviewed. If not already completed with the HIV test, clients should be tested for other STIs, hepatitis B and C, and tuberculosis.

Segregation of distinct variants from Citrus tristeza virus isolate SY568 using aphid transmission.

A well-studied severe isolate of Citrus tristeza virus (CTV) known as SY568 has previously been shown to contain multiple variants of the virus which differ in their genetic and biological characters. Aphid transmission was used in an attempt to segregate some of these variants for further characterization. Resulting infections gave symptoms which varied from asymptomatic to more severe than the inoculum source. RNase protection assays (RPAs) were used to compare nine regions of the CTV genome and determine whether unique strains could be identified. Five aphid-transmitted subcultures, with fingerprints that were different from those of the inoculum sources in at least one genomic area, were then cloned, sequenced, and compared with known isolates. An asymptomatic strain was shown to be different in every area of the CTV genome when examined by RPA and sequencing of selected regions. Mixed-infection studies using graft transmission of the asymptomatic subculture and two of the more severe aphid-transmitted subcultures showed that the mild strain was not able to compete well when in the presence of any of the severe variants tested, and its titer was significantly reduced from that seen in single infection. The mild strain and a selected severe strain were singly graft inoculated into five different citrus hosts (sweet orange, grapefruit, sour orange, lemon, and lime), where they maintained their distinct biological and genetic characteristics.

First Report of Angelonia flower break virus in Nemesia spp. and Other Ornamental Plants in California.

Between June 2006 and July 2007, ornamental plant samples were collected from four counties in California (Riverside, Sacramento, San Diego, and Santa Barbara) and tested for the presence of Angelonia flower break virus (AnFBV) using ELISA (Agdia, Inc., Elkhart, IN). Tissue samples were from propagation facilities or wholesale outlets except those from Riverside County, which were from retail stores. Thirteen positive samples were found in three varieties each of Angelonia and Nemesia spp. and seven varieties of Verbena spp., with at least one positive from each county. Foliar symptoms ranged from asymptomatic to a mild mosaic with distinct flower breaking in the Angelonia spp. Results were confirmed by reverse transcription (RT)-PCR of the coat protein gene (1) and the 1,172-bp amplicons were sequenced. Viral isolates from the three varieties of the Angelonia spp. had 98 to 99% nucleotide similarity and 99 to 100% amino acid identity to the Maryland strain of AnFBV (1; GenBank Accession No. DQ221212), with 91 to 92% nucleotide similarity and 96 to 97% amino acid identity to the Israel and Florida strains (GenBank Accession Nos. DQ223771 and DQ219415). All viral isolates from the Nemesia and Verbena spp. plants had nucleotide similarities of 96 to 98% and 98% amino acid identity to the Israel and Florida strains, with 91 to 92% nucleotide similarity to the Maryland strain. AnFBV has been previously reported in Angelonia and Verbena spp. among other hosts (1,2), but not in Nemesia spp. and not in California. This recently described carmovirus appears to be well established in the state in a variety of ornamental plant species. References: (1) S. Adkins et al. Phytopathology 96:460, 2006. (2) F. Assis-Filho et al. Plant Dis. 90:1115, 2006.

Predictions of tensile strength of binary tablets using linear and power law mixing rules.

There has recently been an increased interest in predicting the tensile strength of binary tablets from the properties of the individual components. In this paper, measurements are reported for tensile strength of tablets compressed from single-component and binary powder mixtures of lactose with microcrystalline cellulose (MCC), and lactose with two types of silicified microcrystalline cellulose (SMCC and SMCC-HD), which are different in compressibility. Measurements show the tensile strength increases with the relative density for single powders, and both with the relative density and the mass fraction of cellulose in the mixtures. It was also observed, for binary mixtures compacted at 50 and 150 MPa, that there was a slight variation in porosity with the mass fraction of celluloses. The predictions of the tensile strength of binary tablets from the characteristics of the single-components was analysed with the extended Ryshkewitch-Duckworth model by assuming both linear and power law mixing rules for the determination of the parameters "tensile strength at zero porosity and bonding capacity constant". As consequence, four models were analysed and compared with measurements using criteria based on the standard deviation from the mean values. Results showed a good prediction using a linear mixing rule combined with the power law. However, as the predictions of these models depend on the powders and the porosity range for the characterization of single-components, none of them can be systematically considered as being the best to predict binary behaviour from data for individual powders.

Behavioural predictors of subsequent hepatitis C diagnosis in a UK clinic sample of HIV positive men who have sex with men.

OBJECTIVE: To explore the associations between self reported high risk sexual behaviours and subsequent diagnosis with hepatitis C virus (HCV) infection. METHODS: The Sex, Health and Anti-Retrovirals Project (SHARP) was a cross sectional study of sexual behaviour in HIV positive, men who have sex with men (MSM) attending a London outpatient clinic. From July 1999 to August 2000 participants completed a computer assisted self interview questionnaire (CASI) on recent sexual behaviour, recreational drug use, and detailed reporting of the last two sexual episodes involving different partners. Results were combined with routine clinic data and subsequent testing for HCV up to 21 April 2005. A new HCV diagnosis was defined as anti-HCV antibody seroconversion or positive HCV RNA following a previous negative. Incident rate ratios (IRR) were calculated using Poisson regression in Stata (version 9). Men contributed time at risk from interview until either their diagnosis or their last negative test result. RESULTS: Of the 422 men who completed questionnaires, 308 (73%) had sufficient clinical and HCV testing data available for analysis. Incident HCV infection was identified in 11 men. Unprotected anal intercourse, more than 30 sex partners in the past year, higher numbers of new anal sex partners, rimming (oro-anal sex), fisting, use of sex toys, and intranasal recreational drug use were associated with HCV. In multivariate analysis only fisting remained associated with HCV (adjusted IRR 6.27, p = 0.005). CONCLUSIONS: In this study of HIV positive MSM, fisting is strongly associated with HCV infection. Where individuals report high risk sexual behaviours, clinicians should offer appropriate testing for HCV infection.

Men who have sex with men: a comparison of a probability sample survey and a community based study.

We compared characteristics of men who have sex with men (MSM) in a probability sample survey with a community based study in London. The majority of men in both surveys reported male sex partner(s) in the last year but MSM recruited through the population based survey had lower levels of HIV risk behaviour, reported fewer sexually transmitted infections and HIV testing than those recruited from gay venues. Community samples are likely to overestimate levels of risk behaviour among all MSM.

First Report of Nemesia ring necrosis virus in North America in Ornamental Plants from California.

During the last several years, two California propagators have detected what was believed to be the tymovirus Scrophularia mottle virus (ScrMV) in several ornamental plant species on the basis of enzyme-linked immunosorbent assay (ELISA) using a ScrMV antibody system. Symptoms were generally mild, ranging from nonsymptomatic to a mild mosaic. Our laboratory confirmed the presence of a tymovirus in one Verbena sp. and two Diascia spp. cultivars on the basis of dsRNA analysis that showed bands of approximately 6,400 and 300 nucleotides representing the genomic and coat protein subgenomic RNAs, respectively. While these plants and those that were experimentally infected (Nicotiana benthamiana and N. clevelandii) also tested positive for ScrMV by ELISA, the host range did not match that published for ScrMV, notably the lack of symptoms in Chenopodium quinoa and the lack of systemic infection in Datura stramonium. A similar host range result was reported in Europe for another tymovirus that cross reacts with ScrMV antiserum, Nemesia ring necrosis virus (NeRNV) (2). Using NeRNV specific primers (1), we used reverse transcription-polymerase chain reaction (RT-PCR) to test plants that had previously tested positive for ScrMV by ELISA and had dsRNAs typical of a tymovirus. An amplicon of the appropriate size (960 bp) for NeRNV was obtained from each of five samples. Using ScrMV specific primers, the same samples failed to amplify the expected product. We have found NeRNV in three Diascia spp., one Verbena sp., and one Nemesia sp. plants in two counties in California (Riverside and San Diego). When the RT-PCR products were sequenced, they all had 99% sequence identities to NeRNV with 4 to 7 single nucleotide changes (GenBank Accession Nos. DQ648150 to DQ648154). Notably, each of the five amplicons had changes at nucleotides 5134 (G to C) and 5549 (G to T) when compared with the European isolates of NeRNV, which did not result in any amino acid changes. To our knowledge, this is the first report of NeRNV in North America and more specifically, in California. References: (1) R. Koenig et al. J. Gen. Virol. 86:1827, 2005. (2) A. L. Skelton et al. Plant Pathol. 53:798, 2004.

Increasing risk behaviour and high levels of undiagnosed HIV infection in a community sample of homosexual men.

OBJECTIVES: To estimate changes in sexual behaviour over time. To examine the proportion of undiagnosed HIV infection in a community sample of homosexual men. To explore the relation between HIV status, diagnosis, and sexual behaviour. METHODS: Five cross sectional surveys of men attending selected gay community venues in London between 1996 and 2000 (n = 8052). Men were recruited in 45 to 58 social venues (including bars, clubs, and saunas) across London. Participants self completed an anonymous behavioural questionnaire. In 2000, participants in community venues provided anonymous saliva samples for testing for anti-HIV antibody. RESULTS: The proportion of men having unprotected anal intercourse (UAI) increased significantly each year from 30% in 1996 to 42% in 2000 (p<<0.001). In 2000, 132 of 1206 (10.9%) saliva samples were HIV antibody positive. Of the HIV saliva antibody positive samples, 43/132 (32.5%) were undiagnosed. Around half of both diagnosed and undiagnosed HIV saliva positive men reported UAI in the past year. Of the 83% of men who reported their current perceived HIV status, 4.1% reported an incorrect status. HIV antibody positivity was associated with increasing numbers of UAI partners, and having a sexually transmitted infection (STI) in the past year (OR 2.15). CONCLUSIONS: Homosexual men continue to report increasing levels of UAI. HIV prevalence is high in this group, with many infections remaining undiagnosed. The high level of risky behaviour in HIV positive men, regardless of whether they are diagnosed, is of public health concern, in an era when HIV prevalence, antiretroviral resistance, and STI incidence are increasing.

Natural Incidence of Mixed Infections and Experimental Cross Protection Between Two Genotypes of Tobacco mild green mosaic virus.

ABSTRACT Isolates of Tobacco mild green mosaic virus (TMGMV), a member of the genus Tobamovirus, from Nicotiana glauca in southern California fall into two major genotypes, large (TMGMV-L) and small (TMGMV-S), distinguishable by the size of the coat protein (CP) subgenomic RNA. Mixed infections in the field were rare (1.6%), even at sites where both genotypes were common in single infections (62% for TMGMV-S; 37% for TMGMV-L). When plants experimentally protected by TMGMV-L were challenged by TMGMV-S, almost complete cross protection (90% of total plants challenged) was observed regardless of the protective time period (minimum 12 h and maximum 14 days). When plants protected by TMGMV-S were challenged with TMGMV-L, complete cross protection was observed when the protective time was 5 to 14 days. However, when the protective time was 3 days or less, protection by TMGMV-S was greatly reduced (11%), with mixed infections of TMGMV-S and -L predominating (69%), and single infections of the challenge virus TMGMVL were frequently observed (20%). When TMGMV-S and -L virions were co-inoculated, the virus progeny from individual plants most often contained only the TMGMV-L genome (61%) or, less frequently (39%), both genotypes. Therefore, TMGMV-L was more competitive than TMGMV-S and was able to displace TMGMV-S in experimental situations. The results obtained from cross-protection experiments in the greenhouse would explain the low frequency of natural mixed infections. It is possible that the experimental superior competitiveness of the novel L genotype has already or will play a role in its abundance in southern California.

Bone blood flow and vascular reactivity.

Blood flow is essential for normal bone growth and bone repair. Like other organs, the regulation of blood flow to bone is complex and involves numerous physiologic mechanisms including the sympathetic nervous system, circulating hormones, and local metabolic factors. Our studies addressed the following questions: (1) Which endogenous vasoconstrictor agents regulate in vivo blood flow to bone? (2) Does a decrease in bone vascular reactivity to vasoconstrictor hormones account for the increase in blood flow during bone healing? (3) Does the endothelium influence bone arteriolar function? An intact bone model was developed in the rat to assess hormonal regulation of in vivo bone blood flow and in vivo bone vascular reactivity. An isolated, perfused bone arteriole preparation was employed to characterize the responsiveness of small resistance-size arterioles (diameter < 100 microm) to vasoconstrictor hormones and to evaluate the role of the vascular endothelium to modulate vascular smooth muscle reactivity. Our results indicate that: (1) though exogenous endothelin is a potent constrictor of the in vivo bone vasculature, endogenous endothelin does not actively regulate in vivo blood flow; (2) the increase in blood flow to a bone injury site is not due to a decrease in bone vascular sensitivity to norepinephrine, and (3) isolated bone arterioles of young rats are very sensitive to vasoconstrictor hormones but exhibit only modest endothelium-mediated vasodilation.

A comparison of high-risk sexual behaviour and HIV testing amongst a bar-going sample of homosexual men in London and Edinburgh.

BACKGROUND: This study compared high-risk sexual and HIV testing behaviour amongst homosexual men recruited from gay bars in London and Edinburgh. METHODS: A cross-sectional survey monitoring high-risk sexual and HIV testing behaviour using a self-completed questionnaire was conducted in November and December 1996. RESULTS: Two thousand, three hundred and ninety-seven questionnaires were returned (1,366 recruited in London and 1,031 in Edinburgh), with a response rate of 77%. A larger proportion of men surveyed in London had had unprotected anal intercourse (UAI) with one or more male partners in the previous year (35%) than in Edinburgh (30%). Men recruited in Edinburgh were less likely to have had an HIV test (54%) than men in London (63%). In both surveys, 25% of men who reported UAI with partners of the same HIV status as themselves also reported never having had an HIV test. CONCLUSIONS: The observed dissimilarities in the HIV epidemic in the two cities may be accounted for by the differences in self-reported high-risk sexual and HIV testing behaviours between the two populations. A large proportion of men in both cities continue to engage in high-risk sexual behaviour suggesting continued transmission of HIV in these populations. Thus, there is a continued need for innovative and relevant health promotion amongst homosexual men in the UK.

Electron microscopy of satellite tobacco mosaic virus crystals: metal-coated, negatively stained and stereo pairs.

Highly purified virions of satellite tobacco mosaic virus (STMV) were found to crystallize at relatively low concentrations (300-500 microg ml(-1)) in pure water. Small crystals of these preparations were examined in the transmission electron microscope after either being rotary shadowcast with metal or negatively stained with 4% uranyl acetate. Stereo views were also obtained of both types of preparations. Stereo pairs of metal-coated crystals provided good three-dimensional images. When stereo pairs of negatively stained crystals were printed from second negatives, they provided striking images although the three-dimensional aspect was not so pronounced. Images of both types of preparations were compared with a computer-generated model of the virus. This model was based on data obtained in earlier X-ray diffraction crystallographic studies. Measurements of crystal axes on the EM images were somewhat lower than those of the computer model. It is assumed the reason for this is the dehydration of crystals during preparation for electron microscopy. The EM images did verify the type of crystal lattice determined in the X-ray diffraction studies. Conversely, knowing the exact unit cell parameters and the distribution of virions in the crystal from X-ray diffraction data aids in the further interpretation of electron micrographs of virus crystals.