Interactions of viruses in Cowpea: effects on growth and yield parameters.

The study was carried out to investigate the effects of inoculating three cowpea cultivars: "OLO II", "OLOYIN" and IT86D-719 with three unrelated viruses: Cowpea aphid-borne mosaic virus (CABMV), genus Potyvirus, Cowpea mottle virus (CMeV), genus Carmovirus and Southern bean mosaic virus (SBMV), genus Sobemovirus singly and in mixture on growth and yield of cultivars at 10 and 30 days after planting (DAP). Generally, the growth and yield of the buffer inoculated control plants were significantly higher than those of the virus inoculated plants. Inoculation of plants at an early age of 10 DAP resulted in more severe effect than inoculations at a later stage of 30 DAP. The average values of plant height and number of leaves produced by plants inoculated 30 DAP were higher than those produced by plants inoculated 10 DAP. Most of the plants inoculated 10 DAP died and did not produce seeds. However, " OLOYIN" cultivar was most tolerant and produced reasonable yields when infected 30 DAP. The effect of single viruses on growth and yield of cultivars showed that CABMV caused more severe effects in IT86D-719, SBMV had the greatest effect on "OLO II" while CMeV induced the greatest effect on "OLOYIN". Yield was greatly reduced in double infections involving CABMV in combination with either CMeV or SBMV in "OLOYIN" and "OLO II", however, there was complete loss in yield of IT86D-719. Triple infection led to complete yield loss in all the three cultivars.

Studies on Maize streak virus and Maize mottle/chlorotic stunt virus in Lagos, Nigeria.

Despite the development and deployment of maize streak-resistant (SR) germ plasm, virus-induced symptoms are still commonly observed on maize in Lagos, Nigeria. Therefore, surveys were conducted between April 2001 and February 2002 to determine the identity, prevalence, and incidence of maize viruses in 18 local government areas (LGAs) in and around Lagos by visual examination and serodiagnostic screening of symptomatic plants. All 112 fields surveyed during the dry season (September to December) and 18 fields surveyed during the late dry season (December to February) had plants infected by Maize streak virus (MSV), whereas 97.1% of the 170 fields surveyed during the wet season (April to August) had plants infected by MSV. Maize mottle/chlorotic stunt virus (MMCSV) was prevalent in 99.1, 88.9, and 67.4% of the fields surveyed during the dry, late dry, and wet seasons, respectively. The incidence of MSV was higher in 16 of the LGAs. The highest incidence of MSV was 18.9%, whereas that of MMCSV was 7.4%. Serodiagnostic screening of leaf samples showing virus-induced symptoms, using antigen-coated plate enzyme-linked immunosorbent assay, indicated that 1,192/1,475 (80.8%) and 949/1,210 (78.4%) of the samples were positive for MSV and MMCSV, respectively. Vector transmission and host range studies confirmed the identity of the viruses. The results confirm the presence of MSV and MMCSV in Lagos and suggest that the use of MSV-susceptible cultivars is still widespread. Methods of ensuring effective utilization of existing SR germ plasm and controlling maize viruses in general are discussed.

Survival and surface adherence ability of bacterial pathogens in oral liquid pharmaceuticals and their containers.

The survival and surface adherence ability of Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa in nutrient broth and in five oral liquid pharmaceuticals (nivaquine syrup, cough mixture, paracetamol elixir, cotrimoxazole and vitamin C) were investigated The bacteria grew more in nutrient broth than in the pharmaceuticals (p < 0. 001) and the recovery of stressed cells was enhanced when 3% Tween 80 was used as the recovery medium as against the use of normal saline (p < 0.01). The Gram-negative bacteria were more adapted to the pharmaceuticals than their Gram-positive counterparts. Klebsiella pneumoniae and Ps. aeruginosa were recovered in large numbers from nivaquine and cotrimoxazole suspensions that did not support the growth of the other bacteria. The effect of bacterial growth on the physico-chemical properties of the pharmaceuticals was also evaluated The properties were not altered significantly except for pH shifts of 0.3 to 1.1 caused by E. coli and S. aureus in paracetamol and vitamin C. Adherence capability was found to correlate with the survival ability of the bacteria. Populations on coupons were significantly higher when nutrient broth was used as the suspending medium compared with any of the pharmaceuticals (p < 0.01). Rubber and plastic coupons were significantly more accessible to the bacteria than glass coupon as revealed by the high population of bacteria recovered from their surfaces.

Survival and surface adherence ability of bacterial pathogens in oral liquid pharmaceuticals and their containers

The survival and surface adherence ability of Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa in nutrient broth and in five oral liquid pharmaceuticals (nivaquine syrup, cough mixture, paracetamol elixir, cotrimoxazole and vitamin C) were investigated The bacteria grew more in nutrient broth than in the pharmaceuticals (p < 0. 001) and the recovery of stressed cells was enhanced when 3 Tween 80 was used as the recovery medium as against the use of normal saline (p < 0.01). The Gram-negative bacteria were more adapted to the pharmaceuticals than their Gram-positive counterparts. Klebsiella pneumoniae and Ps. aeruginosa were recovered in large numbers from nivaquine and cotrimoxazole suspensions that did not support the growth of the other bacteria. The effect of bacterial growth on the physico-chemical properties of the pharmaceuticals was also evaluated The properties were not altered significantly except for pH shifts of 0.3 to 1.1 caused by E. coli and S. aureus in paracetamol and vitamin C. Adherence capability was found to correlate with the survival ability of the bacteria. Populations on coupons were significantly higher when nutrient broth was used as the suspending medium compared with any of the pharmaceuticals (p < 0.01). Rubber and plastic coupons were significantly more accessible to the bacteria than glass coupon as revealed by the high population of bacteria recovered from their surfaces

Properties of a virus isolated from Vernonia amygdalina Del. in Lagos, Nigeria.

A previously uncharacterized virus tentatively named Vernonia green vein-banding virus (VGVBV) was isolated from Vernonia amygdalina Del. ("bitterleaf") from Lagos, Nigeria. The virus was mechanically transmissible but had a narrow host range restricted to Nicotiana benthamiana, Chenopodium quinoa and C. amaranticolor. It was also transmissible in a non-persistent manner by Myzus persicae. The virus was purified from N. benthamiana and about 750 nm long flexuous rod-shaped particles were observed in purified preparations as well as in leaf-dips of Vernonia sp. Inclusion bodies in the form of pinwheels and scrolls were observed in ultrathin sections of Vernonia leaves by electron microscopy. M(r), of the viral coat protein was estimated to be about 34 K. In indirect ELISA, all 20 samples from naturally infected Vernonia sp. reacted positively with a potyvirus-specific monoclonal antibody (MAb) as well as with an antiserum raised against VGVBV. Apart from the homologous antigen, the VGVBV antiserum reacted only with Plum poxvirus (PPV). The VGVBV reacted strongly with the antisera to Bean yellow mosaic virus (BYMV), Bean common mosaic virus (BCMV) and Amaranthus leaf mottle virus (AmLMV) but weakly with antisera to PPV and Cowpea aphid-borne mosaic virus (CABMV) (all members of the family Potyviridae, the genus Potyvirus) in at least one of the assays used (indirect ELISA, dot-blot immunoassay and Western blot analysis). The results of our host range, cytopathological and serological studies and the available literature indicate that a hitherto difficult to transmit VGVBV has only been reported from Nigeria. We consider VGVBV a candidate for a new potyvirus. This virus should be further investigated to collect sufficient data for a qualified proposal of VGVBV as a new potyvirus.

Properties of a virus causing mosaic and leaf curl disease of Celosia argentea L. in Nigeria.

A sap transmissible virus, causing mosaic and leaf curl disease of Celosia argentea, was isolated at vegetable farms in Amuwo Odofin, Tejuoso, and Abule Ado, Lagos, Nigeria. The virus had a restricted host range confined to a few species of the Amaranthaceae, Chenopodiaceae and Solanaceae families. It failed to infect several other species of the Aizoaceae, Brassicaceae, Cucurbitaceae, Fabaceae, Lamiaceae, Malvaceae, Poaceae and Tiliaceae families. The virus was transmitted in a non-persistent manner by Aphis spiraecola and Toxoptera citricidus but not by eight other aphid species tested. There was no evidence of transmission by seeds of C. argentae varieties. The viral coat protein had a relative molecular mass (M(r)) of about 30.2 K. Electron microscopy of purified virus preparations revealed flexuous rod shaped particles of about 750 nm in length. Serological studies were performed using the enzyme-linked immunosorbent assay (ELISA), immunosorbent electron microscopy (ISEM) and Western blot analysis. The virus reacted positively with an universal potyvirus group monoclonal antibody (MoAb) and MoAb P-3-3H8 raised against peanut stripe potyvirus. It also reacted with polyclonal antibodies raised against several potyviruses including asparagus virus-1 (AV-1), turnip mosaic virus (TuMV), maize dwarf mosaic virus (MDMV), watermelon mosaic virus (WMV-2), plum pox virus (PPV), soybean mosaic virus (SoyMV), lettuce mosaic virus (LMV), bean common mosaic virus (BCMV) and beet mosaic virus (BMV) in at least one of the serological assays used. On the basis of host range, mode of transmission, and available literature data, the celosia virus seems to be different from potyviruses previously reported to infect vegetables in Nigeria. The name celosia mosaic virus (CIMV) has been proposed for this virus.