Immunological insights into COVID-19 in Southern Nigeria

Introduction: One of the unexpected outcomes of the COVID-19 pandemic was the relatively low levels of morbidity and mortality in Africa compared to the rest of the world. Nigeria, Africa's most populous nation, accounted for less than 0.01% of the global COVID-19 fatalities. The factors responsible for Nigeria's relatively low loss of life due to COVID-19 are unknown. Also, the correlates of protective immunity to SARS-CoV-2 and the impact of pre-existing immunity on the outcome of the COVID-19 pandemic in Africa are yet to be elucidated. Here, we evaluated the natural and vaccine-induced immune responses from vaccinated, non-vaccinated and convalescent individuals in Southern Nigeria throughout the three waves of the COVID-19 pandemic in Nigeria. We also examined the pre-existing immune responses to SARS-CoV-2 from samples collected prior to the COVID-19 pandemic. Methods: We used spike RBD and N- IgG antibody ELISA to measure binding antibody responses, SARS-CoV-2 pseudotype assay protocol expressing the spike protein of different variants (D614G, Delta, Beta, Omicron BA1) to measure neutralizing antibody responses and nucleoprotein (N) and spike (S1, S2) direct ex vivo interferon gamma (IFNγ) T cell ELISpot to measure T cell responses. Result: Our study demonstrated a similar magnitude of both binding (N-IgG (74% and 62%), S-RBD IgG (70% and 53%) and neutralizing (D614G (49% and 29%), Delta (56% and 47%), Beta (48% and 24%), Omicron BA1 (41% and 21%)) antibody responses from symptomatic and asymptomatic survivors in Nigeria. A similar magnitude was also seen among vaccinated participants. Interestingly, we revealed the presence of preexisting binding antibodies (N-IgG (60%) and S-RBD IgG (44%)) but no neutralizing antibodies from samples collected prior to the pandemic. Discussion: These findings revealed that both vaccinated, non-vaccinated and convalescent individuals in Southern Nigeria make similar magnitude of both binding and cross-reactive neutralizing antibody responses. It supported the presence of preexisting binding antibody responses among some Nigerians prior to the COVID-19 pandemic. Lastly, hybrid immunity and heterologous vaccine boosting induced the strongest binding and broadly neutralizing antibody responses compared to vaccine or infection-acquired immunity alone

Emergence and spread of two SARS-CoV-2 variants of interest in Nigeria.

Identifying the dissemination patterns and impacts of a virus of economic or health importance during a pandemic is crucial, as it informs the public on policies for containment in order to reduce the spread of the virus. In this study, we integrated genomic and travel data to investigate the emergence and spread of the SARS-CoV-2 B.1.1.318 and B.1.525 (Eta) variants of interest in Nigeria and the wider Africa region. By integrating travel data and phylogeographic reconstructions, we find that these two variants that arose during the second wave in Nigeria emerged from within Africa, with the B.1.525 from Nigeria, and then spread to other parts of the world. Data from this study show how regional connectivity of Nigeria drove the spread of these variants of interest to surrounding countries and those connected by air-traffic. Our findings demonstrate the power of genomic analysis when combined with mobility and epidemiological data to identify the drivers of transmission, as bidirectional transmission within and between African nations are grossly underestimated as seen in our import risk index estimates

Some Causes of Poor Performance and Chick Mortality in Farmed Ostriches in Alabama (USA) and Kenya

Commercial ostrich farming is rapidly becoming a desirable alternative source of profitable meat production among smallholder farmers. However, ostrich ranching, particularly, ostrich production is severely constrained by a very high chick mortality rate (up to 40 %). To help rural farmers including those in the developed countries such a s United States of America gain a successful foothold in this potentially lucrative farming enterprise, the causes of chick mortality must be identified and controlled. The present collaborative study was designed to characterize and compare disease causes of mortality in chicks in smallholder ratite farms in Macon and adjoining Counties of Alabama and some selected localities in Kenya. The study established that, in both Alabama (USA) and Kenya, ostrich farmers incur losses of considerable magnitude from a wide range of causes, some of which could not be established. Losses are experienced right from the embryonic stages whereby embryos may develop poorly causing death before hatching. In USA, hatchability was 72 % while in Kenya; hatchability was only 56 % on average. In Kenya, a high mortality rate in the early weeks of life (< 3 weeks) [27-40%] was noted. Pathogens isolated at postmortem from inflamed tissues and septic yolk sacs were mainly common bacteria [abstract truncated]. The Kenya Veterinarian Vol. 28 2005: pp. 6-1

Oedema (exudative diathesis) in Ostriches in Kenya

Ostriches of various ages, unhatched embryos and chicks found to have oedema during postmortem examination are described here. Unhatched eggs and chicks originated from a commercial farm, where there was a complaint of poor hatchability of eggs and high chick mortality. Of 35 embryos examined, 29 (82.9%) had severe subcutaneous oedema either generalized (23) or localized (6). Of 311 chicks, 232 (74.6%) had oedema of varying degrees of severity. In 10 chicks, the oedema was subcutaneous and severe, in 5 it was only serous effusions in body cavities and in 217 it was manifested as wetness of subcutaneous tissues. Adult and juvenile ostriches originated from three farms, where they were kept as pets. Of 22 birds, 16 (72.7%) developed a general sickness and 10 (62>3%) of them died. Postmortem examination revealed emaciation and either subcutaneous oedema or serous effusion in body cavities. Additional lesions included combinations of steatites, haemorrhages and pneumonia. The sick birds responded to improved diets that were also supplemented with multivitamins and minerals. The Kenya Veterinarian Vol. 28 2005: pp. 11-1