Genome wide selection in Citrus breeding.

Genome wide selection (GWS) is essential for the genetic improvement of perennial species such as Citrus because of its ability to increase gain per unit time and to enable the efficient selection of characteristics with low heritability. This study assessed GWS efficiency in a population of Citrus and compared it with selection based on phenotypic data. A total of 180 individual trees from a cross between Pera sweet orange (Citrus sinensis Osbeck) and Murcott tangor (Citrus sinensis Osbeck x Citrus reticulata Blanco) were evaluated for 10 characteristics related to fruit quality. The hybrids were genotyped using 5287 DArT_seqTM (diversity arrays technology) molecular markers and their effects on phenotypes were predicted using the random regression - best linear unbiased predictor (rr-BLUP) method. The predictive ability, prediction bias, and accuracy of GWS were estimated to verify its effectiveness for phenotype prediction. The proportion of genetic variance explained by the markers was also computed. The heritability of the traits, as determined by markers, was 16-28%. The predictive ability of these markers ranged from 0.53 to 0.64, and the regression coefficients between predicted and observed phenotypes were close to unity. Over 35% of the genetic variance was accounted for by the markers. Accuracy estimates with GWS were lower than those obtained by phenotypic analysis; however, GWS was superior in terms of genetic gain per unit time. Thus, GWS may be useful for Citrus breeding as it can predict phenotypes early and accurately, and reduce the length of the selection cycle. This study demonstrates the feasibility of genomic selection in Citrus.

Diversity and Genetic Variation among Brevipalpus Populations from Brazil and Mexico.

Brevipalpus phoenicis s.l. is an economically important vector of the Citrus leprosis virus-C (CiLV-C), one of the most severe diseases attacking citrus orchards worldwide. Effective control strategies for this mite should be designed based on basic information including its population structure, and particularly the factors that influence its dynamics. We sampled sweet orange orchards extensively in eight locations in Brazil and 12 in Mexico. Population genetic structure and genetic variation between both countries, among locations and among sampling sites within locations were evaluated by analysing nucleotide sequence data from fragments of the mitochondrial cytochrome oxidase subunit I (COI). In both countries, B. yothersi was the most common species and was found in almost all locations. Individuals from B. papayensis were found in two locations in Brazil. Brevipalpus yothersi populations collected in Brazil were more genetically diverse (14 haplotypes) than Mexican populations (four haplotypes). Although geographical origin had a low but significant effect (ca. 25%) on the population structure, the greatest effect was from the within location comparison (37.02 %). Potential factors driving our results were discussed.

Citrus leprosis virus C Naturally Infecting Commelina benghalensis, a Prevalent Monocot Weed of Citrus Orchards in Brazil.

There are two bacilliform, rhabdo-like viruses that cause citrus leprosis: Citrus leprosis virus C (CiLV-C), which accumulates in the cytoplasm of infected cells, and Citrus leprosis virus nuclear type (CiLV-N), which accumulates in their nucleus. The first one, the prototype of the new genus Cilevirus, is prevalent and occurs in several countries of the American continent, from Argentina to Mexico (1). The second type, still a tentative member of the Rhabdoviridae family, is of rare occurrence, with a few reports in Brazil and one in Panama (1). Leprosis is particularly important to the Brazilian citrus industry because of the 60 to 80 million dollars spent yearly for the control of Brevipalpus phoenicis (Geijskes, 1939) (Acari: Tenuipalpidae), the vector of the virus (1). For decades, the disease was considered unique to citrus plants; however, greenhouse experiments conducted in the 1990s demonstrated the mechanical transmission of CiLV-C to noncitrus plants (1). Years later, researchers were able to transmit the virus to nonrutaceous hosts using viruliferous mites (1,4). Recently, León et al. (2) reported the occurrence of the first noncitrus plant naturally infected by CiLV-C, the rutaceous Swinglea glutinosa Blanco (Merr.). Tropical spiderworts (Commelina benghalensis L.; Commelinaceae) are monocot weeds commonly found in citrus orchards in Brazil. In a survey conducted in orchards with high incidences of leprosis in the municipalities of Borborema and São José do Rio Preto, State of Sao Paulo, Brazil, tropical spiderworts were found exhibiting necrotic spots with a yellow halo in green leaves and green spots with necrotic center in senescent leaves. Since these symptoms are similar to those caused by CiLV-C in citrus, symptomatic plants were collected and subjected to transmission electron microscopy analyses and reverse transcription-PCR using primers that specifically amplify a region within the putative movement protein gene of the virus (3). Bacilliform virus particles and typical inclusions were seen in the lesions. Bands of the expected 344 bp size were seen in agarose gels of symptomatic samples only. The analysis of the consensus sequence showed 100% identity with CiLV-C sequence available in the GenBank (Accession No. YP_654542.1). Experimental transmission of CiLV-C by B. phoenicis reproduced the lesions in inoculated tropical spiderwort. Also, the virus could be easily transmitted back from C. benghalensis to sweet orange plants. Our data show that this widespread weed is the first monocot as a natural host for CiLV-C. Since tropical spiderwort is a host for B. phoenicis and symptomatic plants were found in two municipalities 130 km apart from each other, it is possible that this weed may serve as reservoir for the virus and play a relevant role in the spread of the disease in the field, but this issue still needs to be addressed in further experiments. References: (1) M. A. Bastianel et al. Plant Dis. 94:284, 2010. (2) M. G. A. Leon et al. Plant Dis. 90:682, 2008. (3) E. C. Locali-Fabris et al. Plant Dis. 87:1317. (4) M. A. Nunes et al. Plant Dis. Online publication. doi:10.1094/PDIS-06-11-0538, 2011.

Detection of Brevipalpus-transmitted viruses in their mite vectors by RT-PCR.

The diagnosis of plant diseases caused by Brevipalpus-transmitted viruses (BrTVs) has been done through the analyses of symptoms, transmission electron microscopy, and RT-PCR of infected plant tissues. Here, we report the detection of Citrus leprosis virus C, Orchid fleck virus, Clerodendrum chlorotic spot virus and Solanum violaefolium ringspot virus in their viruliferous vectors Brevipalpus spp. using specific primer pairs for each of the viruses. The efficiency of virus transmission by Brevipalpus mites is low, so the detection of these pathogens in their vectors could constitute an important tool for studies involving virus-vector relationships, transmission, and monitoring the pathogen prior to the appearance of symptoms in the field.

Dual infection with atypical mycobacteria and Mycobacterium tuberculosis causing cervical lymphadenopathy in a child.

The most common presentation of mycobacterial infection encountered in otolaryngological practice is cervical lymphadenitis. We report a child with an unusual cause of cervical lymphadenopathy, i.e. dual tuberculous infections. This had clinical ramifications as, initially Mycobacterium avium-intracellulare was grown in culture and was resistant to standard anti-tuberculous agents, and hence treated with excision of the lymph node. However, the cultures from the excised lymph node grew out Mycobacterium tuberculosis that was sensitive to standard anti-tuberculous drugs. To our knowledge, no such presentation has been reported previously. We also review the literature on cervical lymphadenitis due to atypical mycobacteria and Mycobacterium tuberculosis, with particular emphasis on clinical presentation, diagnosis and management.

Tuberculosis of the central nervous system in children: a 20-year survey.

OBJECTIVE: To review our experience of central nervous system (CNS) tuberculosis at a major British paediatric tertiary referral centre, following the introduction of CT Scan facilities. METHODS: This was a retrospective case survey (prospective in nine patients) of patients admitted to Great Ormond Street over a 20-year period (1977-1997), who fulfilled criteria for a diagnosis of CNS tuberculosis. Data were collected with regard to the clinical, laboratory and demographic characteristics of patients, as well as results of radiological investigations and data on clinical outcome. RESULTS: We identified 38 children with CNS tuberculosis: 23 with tuberculous meningitis (TBM), 10 with tuberculous meningitis and associated tuberculomas and five with tuberculomas alone. The mean age of this group was 3.7 years, ranging from 8 months to 16 years. Only 14 (37%) were of Caucasian origin. A contact source was identified in 18 patients (47%). Previous BCG had only been given to six (16%). The main clinical symptoms and signs present on admission were alteration in consciousness in 30 patients (79%), focal neurological signs in 25 (66%) and fever in 25 (66%). Seizures were observed in 20 patients (53%) and meningism in 18 (47%). Mycobacterium tuberculosis was either cultured or identified by acid-fast stain from CSF or brain tissue from 24 patients (63%). The Mantoux reaction was positive in 17/33 (51%); abnormalities of the chest X-ray were found in 15 (40%). Cranial CT scans of the patients presenting with TBM showed hydrocephalus in 31 patients (94%), and basilar enhancement in 27 (93%) out of the 29 patients who received intravenous contrast. Anti-tuberculous therapy administered varied according to current recommendations of the period; concurrent steroids were given to 31 patients (82%). Neurosurgical procedures were required in the majority of patients with TBM, 25 (76%). In five patients with TBM, new tuberculoma developed during treatment. The overall mortality for our group of patients was 13%, whilst permanent neurological sequelae were seen in 47% of the patients. None of the patients who received BCG either died or had severe sequelae. Mortality and morbidity rates were higher in the first 10 years of the study and amongst those patients admitted in Stage III disease. CONCLUSIONS: CNS tuberculosis continues to be a condition which carries significant morbidity and mortality. Early diagnosis and prompt initiation of treatment are essential to improve the poor outcome.

Clinical, social and ethical aspects of HIV-1 infections in an Arab Gulf State.

Clinical, social and ethical aspects of HIV-1 infection as occurring in the Arab Gulf State of Qatar are presented. Up until November 1989, 50 patients were reported with HIV infection. In more than 75% of cases, the disease was acquired via transfusion of imported blood; 52% have developed AIDS and 65% of these have died. In response to the problem, the Ministry of Health has established a National AIDS Committee whose major function has been to educate both the medical profession and lay public about the disease and on ways to prevent its spread. Furthermore, the Committee has also taken on the role of patient advocate and has been instrumental in resolving many HIV-related difficulties in the community at large. Specialized HIV clinics have also been set up, with both Qatari and expatriate patients being enrolled in treatment programmes. No expatriate patient has been deported due to infection with HIV. Although many social and ethical issues remain unresolved, it appears that a rational and humane public health policy has been adopted in Qatar with respect to the AIDS threat.

PIP: Described is how the National AIDS Committee of the Arab Gulf State of Qatar has managed medical and public education, screening of immigrant workers, and treatment of HIV-infected persons and AIDS cases. Qatar is unusual for being a rapidly emerging Bedouin Muslim culture with a majority of guest workers, and comprehensive, free, state-of-the-art health care. There were 50 HIV+ patients as of 1989, of whom 52% developed AIDS, and 65% of these have died. After an 18-year old girl with no risk factors except having been transfused with imported blood got AIDS in 1984, all transfused persons were screened. The 50 (26 native Qatari) with HIV included 28 males and 22 females, 31 adults and 19 children under 15. 38 were infected by transfusion, 6 were children of infected mothers, 2 were infected abroad, and the source of infection in 2 men was unknown. 17 have dies, and 3 left Qatar. The Qatar National AIDS Committee is educating the medical profession and the public with press releases, news and television interviews, a brochure, and teaching conferences. Weekly HIV clinics, called "Immunocompromised Host Clinics" are conducted by Board Certified Infectious Disease Physicians, trained nurses, and a dedicated social worker. The AIDS Committee has acted as patient advocate for delicate situations such as school attendance, a divorce, a prison inmate, and objections of health care workers. All patients receive azidothymidine and several are receiving pentamidine. There are special cultural issues, such as difficulty in getting informed consent from illiterate nationals, getting compliance from fatalistic fundamentalist Muslims on contraception. While struggling to design the most humane AIDS policy for natives and expatriate workers, Qatar has opposed the WHO recommendations by screening and refusing entry of infected immigrants.

Childhood immunization in the State of Qatar: Implications for improving coverage.

In Qatar, there is evidence of underuse of the immunization services despite easy access to health care. We therefore undertook a prospective study to determine the vaccination status and, more importantly, the reasons for inadequate immunization of a group of 255 preschool children attending the outpatient care facilities in Doha. A questionnaire was used to obtain relevant information, including parent's educational background. Sixty-six percent of the children were fully immunized for their age group, 12% were partially immunized, and 12% were not immunized. Eighty-eight percent had received their first dose of DPT/OPV, but only 57% had received their first booster by 18 months of age; 76% had received three doses of DPT/OPV. The main reasons for nonimmunized status were misinformation and lack of awareness in parents about vaccination. Parental oversight, misinformation, and medical deferral were the main reasons for partial immunization. Parents of unimmunized children were often illiterate. In Qatar, establishment of an aggressive ongoing public education campaign, as well as strict implementation of the World Health Organization's Expanded Programme on Immunization's policy of screenign all children at every health care contact for the need for vaccination, should substantially increase immunization coverage. Implementation of a recall system for defaulters should also lead to improved immunization rates.

Combined vaccine against measles, mumps, rubella, and varicella.

A combined measles, mumps, rubella, and varicella vaccine produced seroconversions for all four components similar to that found if measles, mumps, and rubella vaccine or live varicella vaccine were given separately. In addition, those exposed to varicella were completely protected or had only a mild rash. Moreover, the reaction rates were not increased if the vaccines were combined. The somewhat lower and delayed serologic response to live varicella vaccine as compared with the combined measles, mumps, rubella, and varicella may have been due to the small amount of varicella vaccine virus used or to its degree of attenuation. Persistence of antibody was observed 1 year postimmunization.

Eczema herpeticum. Clinical and laboratory features.

Eczema herpeticum (EH) is a potentially life-threatening complication that may occur in children with atopic dermatitis. The clinical and laboratory features of EH as seen in 14 children are reported. The mean age of affected children was 34 months. A rapid viral diagnosis was made in 72 percent of patients. In one-third of patients there was a history of herpes labialis in one or other parent in the previous week. In 28 percent of the children, EH was initially thought to be an exacerbation or impetiginization of the underlying dermatitis. Eleven of 14 children were treated with acyclovir (intravenously in eight, orally in three). All patients recovered without sequelae.

Herpes zoster in children with acute lymphocytic leukemia.

Herpes zoster (HZ) occurred in 25% (28/88) of a population of children with acute lymphocytic leukemia (ALL) who were seropositive for varicella zoster virus antibody before its onset; 16.5% (33/199) of the total group of children with ALL developed HZ. There were no deaths and only one significant complication, cutaneous disseminated disease, as a result of HZ. The small number of patients studied may have accounted for the failure to find a significant association between the occurrence of HZ and the type of ALL or chemotherapy protocol employed. Although HZ seemed to be more common in those patients who experience relapses of their leukemia, it did not portend a poor outcome for ALL.

Antibodies to the three major glycoproteins of varicella-zoster virus: search for the relevant host immune response.

Clinical manifestations of chickenpox have occurred in individuals known to have seroconverted after vaccination against varicella. To determine whether these "breakthroughs" might be due to the absence of specific antibodies, we tested sera from vaccinees before or at the time of exposure to varicella for antibodies to the three major glycoproteins of varicella-zoster virus (VZV). Protection could not be correlated with the presence or level of any of these antibodies. Levels of antibodies to glycoproteins before onset of zoster were similar to those in sera of individuals who had had varicella previously and did not develop varicella after household exposure. Thus, protection against infections with VZV cannot be explained by the presence of specific antibodies to glycoproteins.

High prevalence of human immunodeficiency virus infection in children with thalassemia exposed to blood imported from the United States.

PIP: 38.5% or 10 of 26 children with thalassemia who had received blood transfusion have tested positive for HIV at the Hamad General Hospital, Doha, Qatar. Blood for transfusion was obtained from commercial suppliers in Miami, Florida, since late 1970. Since December 1985 all blood for transfusion has been tested for HIV for ELISA kits from Abbott Laboratories, Chicago, Ill, and confirmed by Western Blot. These children ranged from 3-13 years old, mean 7.7, and had received an average of 63.5 transfusions. All had been given at least 30 transfusions. Children testing negative for HIV averaged 35.0 lifetime transfusions. 4 of the affected children had persistent generalized lymphadenopathy, but no other symptoms were recorded.^ieng